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  • 1990-1994  (7,463)
  • Analytical Chemistry and Spectroscopy  (7,463)
  • 1
    Electronic Resource
    Electronic Resource
    New molecular descriptors for 2D and 3D structures. Theory (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 263-272 
    Details
    ISSN: 0886-9383
    Keywords: Molecular descriptors ; Principal component analysis ; Chemometrics ; Pattern recognition ; Total surface area ; PCDD PCDF ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New theoretical molecular indices are defined. They contain information about the whole molecular structure in terms of size, shape, symmetry and atom distribution. These indices are calcualted from the (x, y, z) co-ordinates of a molecule within different weighting schemes in a straightforward manner and represent a very general approach to describe molecules, molecular fragments, macromolecules and molecular conformations in a unitary conceptual framework. Their interpretability is quite evident and is defined by the same mathematical properties as the algorithm used for their calculation. Examples on the total surface area, toxicity of PCDD and PCDF and reaction rate of catalysed reactions show a high modelling power of these indices.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080405
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  • 2
    Electronic Resource
    Electronic Resource
    Generalized rank annihilation method. III: Practical implementation (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 273-285 
    Details
    ISSN: 0886-9383
    Keywords: GRAM ; Least-squares problem ; Eigenvalue problem ; NIPALS ; Performance index ; Condition number ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we discuss the practical implementation of the generalized rank annihilation method (GRAM). The practical implementation comes down to developing a computer program where two critical steps can be distinguished: the construction of the factor space and the oblique rotation of the factors. The construction of the factor space is a least-squares (LS) problem solved by singular value decomposition (SVD), whereas the rotation of the factors is brought about by solving an eigenvalue problem. In the past several formulations for GRAM have been published. The differences essentially come down to solving either a standard eigenvalue problem or a generalized eigenvalue problem. The first objective of this paper is to discuss the numerical stability of the algorithms resulting from these formulations. It is found that the generalized eigenvalue problem is only to be preferred if the construction of the factor space is not performed with maximum precision. This is demonstrated for the case where the dominant factors are calculated by the non-linear iterative partial least-squares (NIPALS) algorithm. Several performance measures are proposed to investigate the numerical accuracy of the computed solution. The previously derived bias and variance are proposed to estimate the number of physically significant digits in the computed solution. The second objective of this paper is to discuss the relevance of theoretical considerations for application of GRAM in the presence of model errors.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080406
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  • 3
    Electronic Resource
    Electronic Resource
    Comments on the DATa ANalysis (DATAN) algorithm and rank annihilation factor analysis for the analysis of correlated spectral data (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 287-292 
    Details
    ISSN: 0886-9383
    Keywords: Rank annihilation ; Principal components ; Procrustes rotation ; Multivariate analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the DATa ANalysis (DATAN) algorithm can be expressed in terms of rank annihilation factor analysis (RAFA). Subsequent advances in RAFA are applied to DATAN to eliminate the problems and restrictions associated with DATAN. The extension of DATAN in terms of the trilinear decomposition algorithm is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080407
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  • 4
    Electronic Resource
    Electronic Resource
    Methods for experimental design, Jacques L. Goupy, Elsevier, Amsterdam, 1993, ISBN 0-444-89529-9, 465 pp., 325 fl (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 293-294 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080408
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  • 5
    Electronic Resource
    Electronic Resource
    Neural networks for chemists. An introduction, Jure Zupan and Johann Gasteiger, VCH, Weinheim, 1993, ISBN 3-527-28603-9 (soft cover), 3-527-28592-X (hard cover), 305 pp., £28 (soft), £57 (hard) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 297-298 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080410
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  • 6
    Electronic Resource
    Electronic Resource
    Reply to comments: ‘Data analysis with minimal assumptions’ (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 301-302 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080412
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  • 7
    Electronic Resource
    Electronic Resource
    Correction (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 303-303 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080413
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  • 8
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080501
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  • 9
    Electronic Resource
    Electronic Resource
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080502
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  • 10
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080101
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  • 11
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080201
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  • 12
    Electronic Resource
    Electronic Resource
    A PLS kernel algorithm for data sets with many variables and fewer objects. Part 1: Theory and algorithm (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 111-125 
    Details
    ISSN: 0886-9383
    Keywords: PLS regression algorithm ; Kernel ; Many-variable data sets ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fast PLS regression algorithm dealing with large data matrices with many variables (K) and fewer objects (N) is presented For such data matrices the classical algorithm is computer-intensive and memory-demanding. Recently, Lindgren et al. (J. Chemometrics, 7, 45-49 (1993)) developed a quick and efficient kernel algorithm for the case with many objects and few variables. The present paper is focused on the opposite case, i.e. many variables and fewer objects. A kernel algorithm is presented based on eigenvectors to the ‘kernel’ matrix XX TYYT, which is a square, non-symmetric matrix of size N × N, where N is the number of objects. Using the kernel matrix and the association matrices XXT (N × N) and YYT (N × N), it is possible to calculate all score and loading vectors and hence conduct a complete PLS regression including diagnostics such as R2. This is done without returning to the original data matrices X and Y. The algorithm is presented in equation form, with proofs of some new properties and as MATLAB code.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080204
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  • 13
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080601
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  • 14
    Electronic Resource
    Electronic Resource
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080602
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  • 15
    Electronic Resource
    Electronic Resource
    Editorial (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 375-376 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080603
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  • 16
    Electronic Resource
    Electronic Resource
    Kernel-based PLS regression; Cross-validation and applications to spectral data (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 377-389 
    Details
    ISSN: 0886-9383
    Keywords: Kernel PLS regression ; Cross-validation ; Model dimensionality ; Multivariate image regression ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multivariate images are very large data structures and any type of regression for their analysis is very computer-intensive. Kernel-based partial least squares (PLS) regression, presented in an earlier paper, makes the calculation phase more rapid and less demanding in computer memory. The present paper is a direct continuation of the first paper. In this study the kernel PLS algorithm is extended to include cross-validation for determination of the optimal model dimensionality. To show the applicability of the kernel algorithm, two examples from multivariate image analysis are used. The first example is an image from an airborne scanner of size 9 × 512 × 512. It consists of nine images which are regressed against a constructed dependent image to test the accuracy of the kernel algorithm when used on large data structures. The second example is a satellite image of size 7 × 512 × 512. Several different regression models are presented together with a comparison of their predictive capabilities. The regression models are also used as examples for showing the use of cross-validation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080604
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  • 17
    Electronic Resource
    Electronic Resource
    Announcement (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 102-102 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080113
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  • 18
    Electronic Resource
    Electronic Resource
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080202
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  • 19
    Electronic Resource
    Electronic Resource
    Conference announcement (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 179-180 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080211
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  • 20
    Electronic Resource
    Electronic Resource
    UNSCRAMBLER II, Extended Memory Version 5.0, available from CAMO A/S, Olav Tryggvasons Gate 24, N-7011 Trondheim, Norway (telephone (+47 73) 51 49 66) or from Camo U.S.A., 722 Port Walk Place, Redwood Shores, CA 94065, U.S.A. (telephone 1-(415) 598-9860). Single-copy price NOK 26,900 commercial, NOK 18,800 non-commercial, NOK 11,900 academic (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 175-176 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080209
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  • 21
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080301
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  • 22
    Electronic Resource
    Electronic Resource
    Announcement (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080611
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  • 23
    Electronic Resource
    Electronic Resource
    Experimental design: A chemometric approach, 2nd edn, Stanley N. Deming and Stephen L. Morgan, Elsevier, Amsterdam, 1993, ISBN 0-444-891 11-0, 453 pp. $177.25, Dfl 310.00 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 446-448 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080610
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  • 24
    Electronic Resource
    Electronic Resource
    Generalized rank annihilation method. II: Bias and variance in the estimated eigenvalues (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 181-203 
    Details
    ISSN: 0886-9383
    Keywords: RAFA ; GRAM ; Eigenvalues ; Bias ; Variance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rank annihilation factor analysis (RAFA) is a method for multicomponent calibration using two data matrices simultaneously, one for the unknown and one for the calibration sample. In its most general form, the generalized rank annihilation method (GRAM), an eigenvalue problem has to be solved. In this second paper expressions are derived for predicting the bias and variance in the eigenvalues of GRAM. These expressions are built on the analogies between a reformulation of the eigenvalue problem and the prediction equations of univariate and multivariate calibration. The error analysis will also be performed for Lorber's formulation of RAFA. It will be demonstrated that, depending on the size of the eigenvalue, large differences in performance must be expected. A bias correction technique is proposed that effectively eliminates the bias if the error in the bias estimate is not too large. The derived expressions are evaluated by Monte Carlo simulations. It is shown that the predictions are satisfactory up to the limit of detection. The results are not sensitive to an incorrect choice of the dimension of the factor space.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080303
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  • 25
    Electronic Resource
    Electronic Resource
    Non-linear least squares refinement with constraints. Evaluation through curve fitting on emulated XPS-like spectra and application to the analysis of carbon fibres (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 221-239 
    Details
    ISSN: 0886-9383
    Keywords: Fitting ; Non-linear ; Least squares ; Refinement ; Constraints ; MSE ; Confidence ; C ls ; XPS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A non-linear least squares iterative refinement has been implemented which shows high performance on a multiple-peak spectrum including baseline or background. Constraints as well as links within a range are introduced to drive the mathematical optimization: each peak parameter (i.e. height, position, Gaussian/Lorentzian mixing ratio and HWHM on both left and right sides) has assigned to it an allowed range of variation and can be strained to be correlated with other parameters belonging either to the same peak (symmetrical peaks) or to other peaks (doublets, triplets, etc.). Peak shapes typical of XP spectra are used and applications in the field of XPS are discussed. Through emulated curves with Poisson distributed noise, the accuracy and precision of back-calculated (refined) parameters have been estimated. Moreover, a confidence level calculated from X2 and degrees of freedom has been suggested to check the overall fitting of experimental curves where the signal-to-noise ratio is a priori unknown. An application to real C ls XP spectra is described as an example and a list of suggestions is given to match operator requirements. Finally, features of NLLSRC are discussed with respect to other approaches.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080305
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  • 26
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080401
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  • 27
    Electronic Resource
    Electronic Resource
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080402
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  • 28
    Electronic Resource
    Electronic Resource
    Editorial (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 243-243 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080403
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  • 29
    Electronic Resource
    Electronic Resource
    Direct distance measures in factor analysis spectral resolution (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 245-261 
    Details
    ISSN: 0886-9383
    Keywords: Factor analysis ; Spectral resolution ; Two-dimensional luminescence ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A factor analysis algorithm that estimates the spectra of mixture components using the set of most dissimilar rows and/or columns is described and illustrated. This algorithm uses the distance as a measure of spectral similarity and is suitable for application to a variety of the bilinear matrix-formatted data types produced by hyphenated and multidimensional analytical techniqes. The algorithm requires that the data matrix contain at least one row or column that corresponds to the pure spectrum of each component to effect accurate spectral resolution. The performance of the method is illustrated using the resolution of excitation and emission spectra of up to four components from experimental fluorescence excitation-emission matrices (EEMs). In the case of the EEM, characteristic bands in an emission spectrum effect resolution of the excitation spectrum of the corresponding component, while characteristic bands in an excitation spectrum lead to resolution of the corresponding emission spectrum. The use of the set of most dissimilar rows and columns to evaluate the degree of overlap in the component spectra and compare the quality of row and column solutions is also described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080404
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  • 30
    Electronic Resource
    Electronic Resource
    Statistical methods in analytical chemistry, Peter C. Meier and Richard E. Zünd, Wiley, New York, 1993, ISBN 0-471-58454-1, 321 pp. (disk included), £49.50 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 295-296 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080409
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  • 31
    Electronic Resource
    Electronic Resource
    Comments on ‘Data analysis with minimal assumptions’ (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 299-301 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080411
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  • 32
    Electronic Resource
    Electronic Resource
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080102
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  • 33
    Electronic Resource
    Electronic Resource
    Statistical thinking and technique for QSAR and related studies. Part II: Specific methods (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 1-20 
    Details
    ISSN: 0886-9383
    Keywords: Discriminant analysis ; Least squares ; Prediction ; Regression ; Relationship ; Structure ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twenty-two contrasting statistical methods are reviewed for their applicability to QSAR studies and similar prediction-oriented fields. Each method is concisely specified prior to explanatory or critical comment.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080103
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    Electronic Resource
    Bootstrap accuracy for non-linear regression models (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 37-44 
    Details
    ISSN: 0886-9383
    Keywords: Bootstrap ; Confidence interval ; Non-linear regression ; Monte Carlo methods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Non-linear regression models describing the toxicity of a mixture of rotenone and pyrethrins as an insecticide, the catalytic dehydration of n-hexyl alcohol and the Michaelis-Menten model for characterizing reaction rates in enzyme systems will be used to illustrate the accuracy of bootstrap methods in non-linear regression. Classical and bootstrap confidence intervals for the parameter estimates will be presented.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080105
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    Electronic Resource
    Interactive variable selection (IVS) for PLS. Part 1: Theory and algorithms (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 349-363 
    Details
    ISSN: 0886-9383
    Keywords: Variable selection ; PLS ; Calibration ; Modelling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified PLS algorithm is introduced with the goal of achieving improved prediction ability. The method, denoted IVS-PLS, is based on dimension-wise selective reweighting of single elements in the PLS weight vector w. Cross-validation, a criterion for the estimation of predictive quality, is used for guiding the selection procedure in the modelling stage. A threshold that controls the size of the selected values in w is put inside a cross-validation loop. This loop is repeated for each dimension and the results are interpreted graphically. The manipulation of w leads to rotation of the classical PLS solution. The results of IVS-PLS are different from simply selecting X-variables prior to modelling. The theory is explained and the algorithm is demonstrated for a simulated data set with 200 variables and 40 objects, representing a typical spectral calibration situation with four analytes. Improvements of up to 70% in external PRESS over the classical PLS algorithm are shown to be possible.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080505
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    Electronic Resource
    Electronic Resource
    On the use of conditional maximization in chemometrics (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 365-370 
    Details
    ISSN: 0886-9383
    Keywords: Censored data ; ECM and EM algorithms ; Incomplete data ; Maximum likehhood ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The purpose of this short communication is to illustrate the use of conditional maximization (CM) in chemometric applications. The CM algorithm is useful in reducing the computational complexity when a high-dimensional and complicated maximization problem arises from fitting chemometric models. It can also be efficiently combined with the expectation-maximization (EM) algorithm for handling incomplete data, a problem that sometimes arises when only a part of the intended data can be collected. Three models from fluorescence spectroscopy are used for illustration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080506
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    Electronic Resource
    Measurement, regression and calibration, Philip Brown, Oxford Statistical Science Series. Vol. 12, Oxford Science Publications, Oxford, 1993, No of pages: 224. Price: £27.50. ISBN 0 19-852245-2 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 371-372 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080507
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    Electronic Resource
    Erratum (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 373-373 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080508
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  • 39
    Electronic Resource
    Electronic Resource
    Generalized rank annihilation method. I: Derivation of eigenvalue problems (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 147-154 
    Details
    ISSN: 0886-9383
    Keywords: RAFA ; GRAM ; Eigenvalue problem ; Complex solution ; Degenerate solution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rank annihilation factor analysis (RAFA) is a method for multicomponent calibration using two data matrices simultaneously, one for the unknown and one for the calibration sample. In its most general form, the generalized rank annihilation method (GRAM), an eigenvalue problem has to be solved. In this first paper different formulations of GRAM are compared and a slightly different eigenvalue problem will be derived. The eigenvectors of this specific eigenvalue problem constitute the transformation matrix that rotates the abstract factors from principal component analysis (PCA) into their physical counterparts. This reformulation of GRAM facilitates a comparison with other PCA-based methods for curve resolution and calibration. Furthermore, we will discuss two characteristics common to all formulations of GRAM, i.e. the distinct possibility of a complex and degenerate solution. It will be shown that a complex solution-contrary to degeneracy-should not arise for components present in both samples for model data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080206
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  • 40
    Electronic Resource
    Electronic Resource
    Compression of nth-order data arrays by B-splines. Part 2: Application to second-order FT-IR spectra (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 127-145 
    Details
    ISSN: 0886-9383
    Keywords: Compression ; Multivariate analysis ; B-splines ; FT-IR spectra ; Second-order ; Two-dimensional ; Hyphenated methods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to improve the storage and CPU time in the numerical analysis of large two-dimensional (hyphenated, second-order) infrared spectra, a data-preprocessing technique (compression) is presented which is based on B-splines. B-splines have been chosen as the compression method since they are wellsuited to model smooth curves. There are two primary goals of compression: a reduction of file size and a reduction of computation when analyzing the compressed representation. The compressed representation of the spectra is used as a substitute for the original representation. For the particular example used here, approximately 0.16 bit per data element was required for the compressed representation in contrast with 16 bits per data element in the uncompressed representation. The compressed representation was further analysed using principal component analysis and compared with a similar analysis on the original data set. The results shows that the principal compotent model of the compressed representation is directly comparable with the principal component model of the original data.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080205
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    Electronic Resource
    Electronic Resource
    Call for papers (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 101-101 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080112
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  • 42
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    Electronic Resource
    Efficiency in research, development and production: The statistical design and analysis of chemical experiments, Leslie Davies, Royal Society of Chemistry, Cambridge, 1993, ISBN 0 85186 137 7 xii + 180 pp., available from The Royal Society of Chemistry, Turpin Distribution Services, Ltd., Blackhorse Road, Letchworth, Herts SG6 IHN, U.K., £19.50 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 177-178 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080210
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    Electronic Resource
    Mathematical analysis of spectral orthogonality, John H. Kalivas and Patrick M. Lang, Marcel Dekker, New York, 1993, ISBN 0-8247-9155-X, 344 pp., $145.00 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 445-446 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080609
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  • 44
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    Electronic Resource
    Classification of pyrolysis mass spectra of biological materials using convex cones (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 305-331 
    Details
    ISSN: 0886-9383
    Keywords: Pyrolysis ; Mass spectroscopy ; Multivariate analysis ; Biological material identification ; Convexity ; Cones ; Subspaces ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work addresses the classification of high-dimensional time-dependent pyrolysis mass spectra of biological samples. The aim was the detection and classification of biological agents, and the developed approach resembles mixture analysis. The data were projected on to a low-dimensional subspace using singular value decomposition. Then a convex cone was formed on this subspace, showing as its corners physically meaningful components of the sample. This technique enabled separation of a biological material signal largely independent of the absolute amount of sample. The detection of the presence of any biological material could be accomplished based on the convex cone alone, without other reference to the mass spectra. Automated clustering of samples was successfully carried out using a minimal spanning tree.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080503
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  • 45
    Electronic Resource
    Electronic Resource
    Quantitative analysis of latex in paper coatings by ATR-FTIR spectroscopy (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 333-347 
    Details
    ISSN: 0886-9383
    Keywords: PLS ; ATR ; Paper ; Resolution ; Infrared ; FTIR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR) has been used to determine the amount of styrene-butadiene latex on the surface of coated papers and to predict the composition of the polymer. Spectrum recording was performed on the sample in its usual form without any modification.For quantitative analysis, partial least squares (PLS) regression, principal component regression (PCR) and multi-linear regression (MLR) were used to calculate models for prediction. The best result is obtained with PLS.We analysed two series of paper samples. The first analysis concerns the measurement of the quantity of latex of a constant quality on the coating surface. For 15 samples the concentration varied between 5 and 25 parts (grams per 100g of mineral pigments). We compared the predictive results at various resolutions. We obtained a relative error of 0.15 parts in latex at 4 cm-1 resolution. The second analysis concerns the measurement of the styrene/butadiene ratio in various types of latex. We obtained a relative error of 0.156 parts for styrene determination and 0.161 parts for butadiene determination.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080504
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  • 46
    Electronic Resource
    Electronic Resource
    Theory of medium-rank second-order calibration with restricted-Tucker models (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 21-36 
    Details
    ISSN: 0886-9383
    Keywords: GRAM ; Tucker ; Unfold ; NBRA ; Second-order ; Three-way ; PARAFAC ; Trilinear ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If an analytical instrument or instrumental method gives a response matrix when analyzing a pure analyte, the instrument or instrumental method is called a second-order method. Second-order methods that generate a response matrix for a pure analyte of rank one are called rank-one second-order methods. If the response matrix of a pure analyte is not rank one, essentially two cases exist: medium rank (between two and five) and high rank (greater than five). Subsequently, medium- and high-rank second-order calibration tries to use medium- and high-rank second-order methods to analyze for analytes of interest in a mixture. A particular advantage of second-order methods is the ability to analyze for analytes of interest in a mixture which contains unknown interferences. Keeping this advantage is the challenge on moving away from rank-one second-order calibration methods. In this paper a medium-rank second-order calibration method is proposed based on least-squares restricted Tucker models. With this method the second-order advantage is retained.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080104
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  • 47
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    Electronic Resource
    Error analysis of the generalized rank annihilation method (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 45-63 
    Details
    ISSN: 0886-9383
    Keywords: GRAM ; GSVD ; Propagation of errorS ; Correlated noise ; Uncorrelated noise ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of correlated and uncorrelated random errors on the precision of predicted quantitative and qualitative information obtained by analysis with the generalized rank annihilation method (GRAM) are shown. These are discussed in terms of propagation of errors through the algorithm. The effects of colinearity, noise level and noise distribution are compared and discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080106
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    Electronic Resource
    A graphical technique for assessing differences among a set of rankings (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 81-93 
    Details
    ISSN: 0886-9383
    Keywords: Sensory evaluation ; Cumulative ranks ; Assessor variation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A graphical method of assessing differences between sets of rankings based on cumulative ranks is developed. The method can be used to identify rankings that differ over all or just part of the range of objects ranked. The method is applied to an example of sensory evaluation of green peas in which ten assessors scored six attributes on each of 60 samples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080108
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    Electronic Resource
    Application of a genetic algorithm to feature selection under full validation conditions and to outlier detection (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 65-79 
    Details
    ISSN: 0886-9383
    Keywords: Genetic algorithms ; Full validation ; Feature selection ; Outlier detection ; Multivariate analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Genetic algorithms have been proved to be a very efficient method in the feature selection problem. However, as for every other method, if the validation of the results is performed in an incomplete way, erroneous conclusions can be drawn. In this paper a development of a previous genetic algorithm is presented so that a full validation of the results can be obtained. Furthermore, this algorithm has been shown to perform very well also as an outlier detector, allowing easy identification of the presence of outliers even in cases where the ‘classical’ techniques fail.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080107
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  • 50
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    Electronic Resource
    Adaptive, global, extended Kalman filters for training feedforward neural networks (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 391-407 
    Details
    ISSN: 0886-9383
    Keywords: Neural networks ; Non-linear multivariate regression ; Pattern classification ; Kalman filter ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Finding methods for the optimization of weights in feedforward neural networks has become an ongoing developmental process in connectionist research. The current focus on finding new methods for the optimization of weights is mostly the result of the slow and unreliable convergence properties of the gradient descent optimization used in the original back-propagation algorithm. More accurate and computationally expensive second-order gradient methods have displaced earlier first-order gradient optimization of the network connection weights. The global, extended Kalman filter is among the most accurate and computationally expensive of these second-order weight optimization methods. The iterative, second-order nature of the filter results in a large number of calculations for each sweep of the training set. This can increase the training time dramatically when training is conducted with data sets that contain large numbers of training patterns. In this paper an adaptive variant of the global, extended Kalman filter that exhibits substantially improved convergence properties is presented and discussed. The adaptive mechanism permits more rapid convergence of network training by identifying data that contain redundant information and avoiding calculations based on this redundant information.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080605
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    Electronic Resource
    A frequency deconvolution procedure using a conjugate gradient minimization method with suitable constraints (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 409-421 
    Details
    ISSN: 0886-9383
    Keywords: Deconvolution ; FT-IR spectroscopy ; Protein conformations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a variety of spectroscopic techniques the fundamental problem exists of determination of the individual spectral components, intrinsically overlapped in the measured spectrum. This is a typical deconvolution problem and several methods and techniques have been proposed for its solution in the technical literature, but suggestions of new approaches are still of interest. A new deconvolution procedure is presented here based on the use of the conjugate gradient minimization algorithm with the addition of sutiable constraints directly obtained by the application to the measured spectrum of the second-derivative operator or more sophisticated resolution enhancement procedures. Since in the examined case deconvolution essentially requires the minimization of a non-convex function, the use of such constraints is extremely important to supply suitable input parameters to the conjugate gradient algorithm to avoid obtaining minimum points which have no physical meaning. In our case each spectral compoent used for deconvolution has been assumed to have a Gaussian analytical definition fully identified by three parameters (amplitude, central frequency, spectral bandwidth), so that the input values required to start the deconvolution process are the number M of Gaussian components and 3M suitable initial approximations of the parameters above. It is shown that all this information can be obtained from the measured data. The deconvolution procedure was implemented by a FORTRAN Microsoft Version 5.1 program and experimental results relative to spectroscopic data obtained by FT-IR analysis of human serum albumin are reported. The results are discussed and compared with data obtained by the use of other techniques.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080606
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    Electronic Resource
    Use of double windowing, variable selection, variable ranking and resolvability indices in window factor analysis (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 423-437 
    Details
    ISSN: 0886-9383
    Keywords: Resolvability ; Evolutionary factor analysis ; Variable selection ; Window factor analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for selecting variables in the non-sequential direction of a two-way data matrix (e.g. wavelength in diode array HPLC) is described. Composition 1 and 2 resolvability indices are calculated according to the size of eigenvalues of uncentred data matrices as a window is moved along the sequential direction. A double-window technique is then performed where resolvability indices are calculated as a window is moved along the non-sequential direction. Some regions have higher resolvability indices and hence are more useful for resolution. Variables are ranked according to resolvability. Two simulations are analysed and it is shown that it is possible to obtain good resolution on a small subset of the original variables.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080607
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    Electronic Resource
    PCB method applied to material design - computer-aided synthesis of BiPbSrCaCuOF superconductor (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 439-443 
    Details
    ISSN: 0886-9383
    Keywords: Pattern recognition ; Principal component analysis ; Inverse mapping ; Optimization ; Material design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An inverse mapping method called PCB (principal component backing), in which the point representing an unknown sample from a low-dimensional principal component subspace is back-projected to the high-dimensional original feature space, is proposed. Two sorts of boundary conditions, non-linear inverse mapping and linear inverse mapping, are used to obtain an accurate solution in the PCB method. The method is applied to the material design of high-Tc superconductors, predicting the composition and process conditions for the synthesis of F-doped Bi-based materials. Samples in the ‘optimal’ region with the highest Tc of the Bi-based ceramics have been predicted.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080608
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    Electronic Resource
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080302
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    Electronic Resource
    Identifying significant effects in fractional factorial experiments (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 205-219 
    Details
    ISSN: 0886-9383
    Keywords: Fractional factorial design ; Significant effects ; ANOVA ; Probability plotting ; Bayes plot ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents a method for identifying significant effects in fractional factorial designs. The method is based on comparing functions of the estimated effects with a scale invariant reference distribution. The method is illustrated and compared with alternative techniques on a dataset from processed cheese production. The method corresponded well to other methods (probability plotting and Bayes plot) that do not make use of error estimates. These methods were better than F-tests with few (two or four) degrees of freedom for error.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080304
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    Evaluation and control of measurements, John Mandel, Quality and Reliability Series, Marcel Dekker, New York, 1991, ISBN O-8247-8531-2, xi + 249 pp. £58.77 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 241-241 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080306
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  • 57
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    Electronic Resource
    The Taguchi influence on designed experiments (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 103-110 
    Details
    ISSN: 0886-9383
    Keywords: Taguchi ; Robust design ; Design of experiments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper is intended to convey the essence of Taguchi's design approach to chemists and others with an interest in chemometrics. Although most Taguchi-style applications worldwide have been in electronics and in elaborately transformed manufactures, examples are increasingly found in chemical processes and in the food industry.Foremost among Taguchi's contributions is the concept of designing processes and products to be robust to the uncontrollable environmental influences which they experience during their operation or lifetime. This concept is explained with a worked example.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080203
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    SCAN (Software for Chemometric Analysis), available from JerII, Inc., North American Office: 790 Esplanada, Stanford, CA 94305, U.S.A. (telephone (415) 856-3401); European Office: via V. Pisani 13, 20124 Milano, Italy (telephone 39-2-26603247). Price US$ 3000 commercial, US$ 2000 academic (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 95-96 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080109
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    TRIC, The First Conference on Three-way Methods in Chemistry, Epe, Netherlands, 227-25 August, 1993 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 97-98 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080110
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    CHESM-93, Chemometrics and Environmetrics Meeting, Bologna Italy, 21-24 August 1993 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 99-100 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080111
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  • 61
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    Slowly converging parafac sequences: Swamps and two-factor degeneracies (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 155-168 
    Details
    ISSN: 0886-9383
    Keywords: Trilinear models ; Tensorial resolution ; PARAFAC ; Swamps ; Two-factor degeneracy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The alternating least squares PARAFAC algorithm is a useful tool for resolving trilinear three-way data arrays. Occasionally, however, it becomes bogged down for many iterations in the vicinity of a poor quality resolution before moving on to a much superior optimum fit. We investigate this behavior in a simulation study and suggest ways of overcoming the obstacles it presents.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080207
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    Comments on the PLS kernel algorithm (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 169-174 
    Details
    ISSN: 0886-9383
    Keywords: Kernel algorithm ; PLS ; SVD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lindgren et al. (J. Chemometrics, 7, 45-49 (1993)) published a so-called kernel algorithm for PLS regression of Y against X when the number of objects is very large. The algorithm is based solely on deflation of the cross-product matrices XTX, YTY and XTY. The algorithm is now described in a shorter and more transparent way and compared with a similar algorithm for the singular value decomposition of XTY.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080208
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    Laser-desorption Fourier-transform mass spectrometry of triazines adsorbed on solid-phase extraction membranesContribution from the 2nd European FTMS Workshop, Antwerp, Belgium, September 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 22-25 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Until the present, analysis of aqueous solutions of atrazine has been conducted using a combination of liquid chromatography or gas chromatography with mass spectrometry, after a preconcentration step. We explore herein a new approach for studying support-phase-extracted atrazine and hydroxyatrazine samples. Solid-phase extraction membranes are inserted directly into the cell of a Fourier-transform mass spectrometer for analysis after laser ionization. It appears that atrazine and its metabolite have very different ionization processes. In the case of hydroxyatrazine, the [M + H]+ ion signal can be correlated to the concentration of the extracted solution. These encouraging results might open the route to a quantification method.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/rcm.1290080105
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    The Fourier-transform laser microprobe mass spectrometer with external ion source as a tool for inorganic micro-analysisContribution from the 2nd European FTMS Workshop, Antwerp. Belgium, September 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 32-39 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Focused-laser ionization of solids and subsequent analysis of the generated ions by Fourier-transform mass spectrometry is suitable for the characterization of inorganic and organic constituents. This paper describes selected examples to illustrate the capability of structural characterization of inorganic substances and the problems associated with the critical nature of the energy deposition phenomena which can complicate the use of the method. Selected examples from practical problem solving in material applications are presented to evidence the feasibility of local analysis by Fourier-transform laser microprobe mass spectrometry.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080107
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    In situ analysis of a new perylene quinone in lichens by Fourier-transform laser microprobe mass spectrometry with external sourceContribution from the 2nd European FTMS Workshop, Antwerp, Belgium, September 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 46-52 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The application of Fourier-transform laser microprobe mass spectrometry to lichens is described. The in situ detection of a new perylene quinone in samples of the tropical species Laurera sanguinaria Malme and Graphis haematites Fée was achieved with minimal specimen preparation. The high mass resolution and mass accuracy of the instrument eliminates the need for additional characterization of the isolated substances by high resolution electron impact mass spectrometry and direct introduction probe.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080109
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  • 66
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    Laser-desorption Fourier-transform mass spectrometry of [Ta6X12]X2·8H2O, X=C1, BrContribution from the 2nd European FTMS Workshop, Antwerp, Belgium, September 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 56-58 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The gas phase of hexanuclear Ta clusters of type [Ta6X12]X2·8H2O, X=Cl, Br was investigated using laser-desorption Fourier-transform mass spectrometry. The [Ta6X12]X2- ions (m/z=1581 for X=Cl, m/z=2205 for X=Br) are the most characteristic peaks in their negative-ion laser-desorption mass spectra. Additional fragmentations observed are the result of loss of halogen and metal from [Ta6X12]X2-. Positive ions are observed only in the laser-desorption mass spectra of [Ta6Br12]Br·8H2O.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080111
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    Ion-trap mass spectrometry with an inductively coupled plasma sourcePaper presented in part at the 41st ASMS Conference on Mass Spectrometry and Allied Topics, 30 May-4 June, 1993, San Francisco, CA, USA. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 71-76 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new mass spectrometry technique using an inductively coupled plasma (ICP) ionization source and an ion-trap mass spectrometer (ITMS) detector is described and evaluated for elemental and isotopic analysis. Initial results obtained with the ICP-ITMS technique include sub-ppb detection of bare ions for, most elements, complete destruction of typical polyatomic matrix ions (e.g., CIO+, ArO+, and ArCl+), and effective neutralization of strong Ar+ ion currents. The latter effects allow observation of clearer mass spectra at m/z 〈 80 and potentially improved detection of ‘problem’ elements in ICP-MS (e.g., K, Ca, V, Fe, As, and Se). Formation of poly-oxide and -hydroxide ions of metals with high oxide bond strengths were observed and require system modifications to alleviate.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080114
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    Identification of phosphorylated peptides from complex mixtures using negative-ion orifice-potential stepping and capillary liquid chromatography/electrospray ionization mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 94-98 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A rapid method for identifying and characterizing sites of phosphorylation of peptides and proteins is described. High-performance capillary liquid chromatography (HPLC) coupled with electrospray ionization mass spectrometry (ESI-MS) is used to distinguish non-phosphorylated and phosphorylated peptides originating from mixtures as complex as enzyme digests. The method relies on the ability to produce a fragment ion characteristic and unique to phosphopeptides (m/z 79, PO3-) by stepping the orifice potential of the mass spectrometer as a function of mass. At low m/z values, a high orifice potential is applied to induce extensive fragmentation of the peptide, leading to the formation of the m/z 79 phosphate-derived ion. This method is analogous to that described by Carr et al. for the identification of glycopeptides from enzymatic digestion of glycoproteins (S.A. Carr, M. J. Huddleston, M. F. Bean, Protein Science 2, 183 (1993)). The method was first evaluated and validated for a mixture of non-, mono- and di-phosphorylated synthetic peptides. Both mono- and di-phophorylated peptides were found to generate fragment ions characteristic of PO3- whereas the non-phosphorylated peptide did not. Application of the method was extended to identifying phosphopeptides generated from an endoprotease Lys-C digestion of β-casein. Both the expected mono- and tetra-phosphorylated Lys-C peptides were observed and identified rapidly in the LC/SEI-MS analysis. The procedure was used additionally to identify the site(s) of phosphorylation of the cytosolic non-receptor tyrosine kinase, pp60c-src.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080118
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    Fast-atom bombardment mass spectrometry of new polydentate schiff bases. 1. The case of variously substituted mono-and bis-salicylaldimine derivatives (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 111-119 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The mass spectrometric behaviour of ten variously substituted mono- and bis-salicylaldimine derivatives has been studied by fast-atom bombardment and metastable-ion studies. In general, well detectable protonated molecules are present and fragmentation processes mainly related to aldimine chain cleavages are evidenced. Interesting cyclization reactions leading to particularly stable product ions are discussed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080121
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    A novel hydrogen rearrangement of bifunctional o-xylylene derivatives in chemical ionization mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 126-128 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A novel hydrogen rearrangement reaction was found in benzyl ions that have a (benzyl) group (Z=O or N) at their ortho position. From deuterium labeling experiments, mass analyzed ion kinetic energy spectra with collisional activation, and examination of structure-peak intensity correlation, a mechanism is proposed which involves a direct transfer of hydrogen (hydride) to the structurally remote but spatially close cationic center. The possibility of an alternative, less likely mechanism including an ion/neutral complex and/or a proton-bridged complex has also been discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080123
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    Electrospray tandem mass spectrometry in the diagnosis of organic acidemiasPaper presented in part at the British Mass Spectrometry Society Meeting, Canterbury, 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 129-133 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A novel procedure based on electrospray tandem mass spectrometry (ESI-MS/MS) has been used in the diagnosis of organic acidemias. The method is based on the determination of acylcarnitine profiles from blood spots collected on Guthrie cards. The acylcarnitines are extracted with methanol, derivatized to their butyl esters and analyzed by ESI-MS/MS. Precursor-ion scanning of the common fragment at m/z 85 of the butyl esters yields highly diagnostic acylcarnitine profiles. Analysis time is one minute per sample and is fully automated. Examples are given of normal profiles, of profiles from two patients with fatty acid oxidation defects, and of a case of propionic acidemia. The technique is simple, rapid and specific, and shows potential for routine application in neonatal screening of organic acidemias.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080124
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    Calender of events (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. i 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080127
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    Investigation of a series of neuroactive glycine dipeptide derivatives by fast-atom bombardment and mass-selected collision-induced dissociation mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 134-138 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Glycylglycine (glygly) and 40 related acetamide derivatives were synthesized and investigated by fast-atom bombardment mass spectrometry. The protonated molecules were mass selected and their collision-induced dissociations were analyzed by tandem mass spectrometry. The data obtained allow a fragmentation pattern to be established for these glygly analogues and permit detailed structural information on the main fragment ions to be ascertained.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080125
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    Recent Events (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 139-140 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080126
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994) 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080201
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    Total yield measurements in matrix-assisted laser desorption using a quartz crystal microbalance (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 149-154 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A quartz crystal microbalance (QCM) is employed to determine the desorption yield of neutral particles in matrix-assisted laser desorption ionization. For ferulic acid, the matrix substance used, the QCM mass resolution of 1 ng corresponds to a detection limit of ≍1012 particles. Sample exposure effects are studied at different fluences by measuring the total desorption yield after consecutive laser pulses fired on the same spot on the sample. The dependence of the total yield on the fluence is studied for different angles of incidence of the laser beam. Varying the distance between the QCM and the sample yields information about the angular spread of the desorbed neutral particles. Additional information about the fluence threshold for the production of charged particles is gained by direct electronic measurements of sample charging.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080204
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    A review of the collision-induced dissociations of deprotonated dipeptides and tripeptides. An aid to structure determination (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 169-173 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The structures of underivatized di- and tripeptides may be determined from a consideration of the collision-induced dissociations of their [M - H]- ions. There are three types of fragmentation, viz. (i) the backbone cleavage which provides sequencing information, (ii) α side-chain cleavage irrespective of the position of the amino acid residue, and (iii) cleavages which are characteristic of amino acid residues in specific positions, in particular the N- or C-terminal positions.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080209
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    Study of anticancer drug interaction with DNA by means of particle-induced desorption mass spectrometry: Prospydine and deoxyguanosine-5′-monophosphate (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 195-198 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Using 252CF particle desorption mass spectrometry, the interaction between an antitumour drug prospydine (Pro) and deoxyguanosine-5′-monophosphate (pdG) has been studied. The adduct which corresponds to a peak at m/z 524.5 and which occurs as a result of the particular degradation of Pro during its alkalating of pdG has been found.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080214
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    Observation of large multimers in the electrospray ionization mass spectrometry of peptides (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 211-216 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Large multimeric ions were detected from electrospray ionization (ESI) mass spectrometry of peptides, using a quadrupole mass spectrometer of standard mass range. Multimers, up to heptamers, were seen for angiotensin I; and multimers, up to pentamers, were observed for renin substrate. The appearance of the multimeric species could be controlled by manipulation of sampling conditions in the ESI interface. The relevance of the observation of large multimers to proposed mechanisms of ESI is discussed. Implications of the observation of large multimers to efforts to deduce higher order structure of biomolecules from ESI mass spectrometric experiments are also noted.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080217
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    Methods in molecular biology, volume 17: Spectroscopic Methods and Analyses—NMR, Mass Spectrometry, and Metalloprotein Techniques EDITED BY C. JONES, B. MULLOY AND A. H. THOMAS Published by Hamana Press. Totowa, New Jersey, 1993 ISBN 0896032159 Price £53.00 (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 224-224 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080220
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    Characterization of glucuronic acid conjugates of a novel angiotensin receptor antagonist (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 217-221 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Nanogram quantities of glucuronic acid conjugates of GR117289 in rat and dog bile have been analysed by semi-microbore high-performance liquid chromatography (HPLC)/ionspray mass spectrometry with on-line UV diode array detection. The determination of drug metabolites in bile has often proved problematical due to the large number of endogenous components in this biological matrix, in particular the bile acids. Semi-microbore HPLC is useful for concentrating small quantities of material and, in combination with an on-line diode array detector, for distinguishing between drug related and endogenous components. A novel angiotensin II receptor antagonist, GR117289, had proved difficult to analyse by thermospray mass spectrometry because of its thermal lability. The use of the less thermally dependent technique of ionspray mass spectrometry allowed the characterization of nanogram quantities of glucuronic acid metabolites of GR117289 in bile.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/rcm.1290080218
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    Liquid chromatography/mass spectrometry analyses of small molecules using electrospray and fast-atom bombardment ionizationPaper presented at 10th (Montreux) Symposium on LC/MS at Cornell University, 21-23 July, 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 252-257 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Electrospray ionization and fast-atom bombardment (FAB) are both soft ionization techniques which typically give prominent molecular ions of thermally labile and highly polar molecules. These two complementary techniques were compared on the same magnetic sector mass spectrometer, a Finnigan MAT 900. Comparisons were made of sensitivity, versatility, ease of use, and most importantly for our work, structure elucidation of unknowns arising from research with agricultural chemicals. Both known standards and ‘real world’ unknowns were analyzed by liquid chromatography/mass spectrometry (LC/MS) with both interfaces. The same reversed-phase micro-LC system was used with both ionization techniques, using 0.32 mm i.d. packed capillary LC columns at flow rates of 1-2 μL/min. Improved performance in the continuous-flow FAB mode was obtained by use of a screen target. The advantages, disadvantages and similarities of these two ionization techniques are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080306
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    Single-electron capture spectra for Ar3+ in argon and xenon (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 258-261 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: High-resolution translational energy spectra have been obtained for Ar2+ ions resulting from single-electron capture by 9 keV Ar3+ ions in argon and xenon gas targets. Our result for Ar3+ in argon is broadly in agreement with previous high-resolution studies, but we have further successfully assigned reaction channels to three peaks which were previously observed but not definitively identified. These channels appear to involve capture of a 3s-electron from the target argon atom to form Ar+ ions in the first excited state Ar+[3s3p6 2S]. The capture spectrum for Ar3+ in xenon displays eleven relatively well defined peaks with exothermic energy changes in the range of 4-12 eV. However, these capture channels are difficult to identify with certainty because they involve capture into closely spaced high excited states of Ar2+, and are further complicated by the splitting (1.31 eV) of the ground-state doublet 2P3/2, 1/20 target Xe+ product ion. There are over one hundred competing channels, comprising three entrance and over forty exit channels, within this range of energy change. Tentative assignments of capture channels have been made, guided by electron-core configuration and spin-conservation requirements.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080307
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  • 84
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    Electronic Resource
    Collision-induced dissociation of some protonated peptides with and without mass selection (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 274-279 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Collision-induced dissociation (CID) of several protonated peptides formed by positive-ion electrospray (ES+) and by Cs+ fast-ion bombardment are reported. The CID spectra of ions formed by the first ionization method were effected at elevated extraction cone voltages within the ion source of a single quadrupole instrument, while linked-fields-scan measurements at constant B/E of ions formed by the latter technique were performed within the collision cell of a trisector instrument. For molecular masses below 1000 Da, the two sets of spectra yielded identical sequencing information; however, for higher molecular masses the similarity was less evident. This divergence between the two sets of measurements is partially attributed to dominant doubly charged ions and less efficient dissociation of sodium adduct ions at elevated cone voltages.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080310
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  • 85
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    Electronic Resource
    Modern methods for trace element determination C. VANDECASTEELE C. B. BLOCK Published by John Wiley & Sons, Chichester, 1993 ISBN 0471940399 Price £45.00 (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 290-290 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080314
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  • 86
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994) 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080401
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  • 87
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    Electronic Resource
    Simple and sensitive quantitation method for mevalonic acid in plasma using gas chromatography/mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 377-380 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The combination of gas chromatography and mass spectrometry using a polar capillary column and isobutane chemical ionization made it possible to determine mevalonic acid (MVA) as the lactone at subnanogram levels using 1 mL of plasma. The pretreatment procedure consisted of only three steps, namely lactonization, washing with chloroform and liquid/liquid extraction. This simple, rapid and sensitive method, having good precision and accuracy, is useful for evaluating the change of plasma MVA, which is well correlated with whole-body cholesterol biosynthesis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080507
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  • 88
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    Electronic Resource
    Fragmentation of vinyl triflates by electron impact. Mechanism of an unusual double hydrogen atom transfer reaction (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 427-431 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The main fragmentation pathway of vinyl triflates in mass spectra involves the loss of CF3SO2·, followed by the loss of olefin and/or CO. The loss of TfOH takes place with fragmentation of a vinylic C—H bond. TfOH2+ ions are formed via regiospecific double hydrogen transfer from five- and six-membered cyclic triflates.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080517
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  • 89
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    Biological mass spectrometry: Present and future Edited by T. MATSUO, R. M. CAPRIOLI, M. L. GROSS and Y. SEYAMA Published by John Wiley & Sons, Chichester, 1994 ISBN 0 471 93896 3 Price £120.00; 666 pp. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 435-435 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080519
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  • 90
    Electronic Resource
    Electronic Resource
    Determination of acid sites in solid catalysts by mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 599-602 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: This paper reports a temperature-programmed desorption mass spectrometry method for determining the nature, number and distribution, according to relative strength, of acid sites in solid catalysts. By using pyridine as the titrant, the overall, Brönsted (B) and Lewis (L) acidities are determined. The Brönsted acidity is obtained individually by titration with 2,6-dimethylpyridine, whereas the Lewis acidity is calculated by difference. The desorption temperatures for the amines are used as measures of the relative strengths of the different types of acid sites. The results obtained are compared with those provided by a UV-visible spectrophotometric method reported elsewhere (J. M. Campelo et al., Can. J. Chem. Vol. 61, p. 544 (1983)).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080806
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  • 91
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    Electronic Resource
    Multiphoton ionization and dissociation of nitrotoluene isomers by UV laser light (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 607-614 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The photofragmentation of the nitrotoluene isomers in the gas phase is studied in the wavelength region 210-270 nm using a pulsed UV laser in conjunction with a time-of-flight mass spectrometer. Laser-induced mass spectra are analysed and compared with those produced by the electron impact technique. The generation of the observed fragment ions is explained by invoking different fragmentation pathways followed by these molecules. Observed differences in the mass spectra of the ortho- meta-, and para-nitrotoluene isomers and in the wavelength dependence of the NO fragment released from these molecules are discussed as a possible way of providing a laser-based method for their identification.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080808
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  • 92
    Electronic Resource
    Electronic Resource
    Mass spectrometry of some imidazoles of pharmacological interest (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 639-644 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electron-impact induced fragmentation processes of nine differently N-substituted imidazoles were studied by means of mass-analyzed ion kinetic energy spectrometry. The compounds under study show a mass spectrometric behaviour different from that observed for other imidazoles already studied. In fact all the observed decompositions are related to the substituent chains.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080814
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  • 93
    Electronic Resource
    Electronic Resource
    Product announcements (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 671-671 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080821
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  • 94
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    Electronic Resource
    Picolinic acid as a matrix for laser mass spectrometry of nucleic acids and proteins (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 673-677 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We found that picolinic acid is a very good matrix for matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry of oligonucleotides, proteins and tRNA. Among the oligonucleotides, picolinic acid was shown to be effective for homo-oligonucleotides, d(G)40 and d(C)60, and for mixed-base oligonucleotides up to 190 bases. In the case of the single-stranded oligonucleotides, and of double-stranded ones as well, only parent ions corresponding to single-stranded DNA were observed. The efficiency for MALDI of oligonucleotides using the picolinic acid matrix was superior to that using 3-hydroxypicolinic acid. MALDI of transfer RNA phenylalanine-specific (tRNAphe), a 76-base ribonucleic acid, was detected with a signal-to-noise ratio of 〉10. By comparison with 3-hydroxypicolinic acid the results with picolinic acid are notably superior for all oligonucleotides.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080902
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  • 95
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    Electronic Resource
    Comparison of peptide analysis results for horse, bovine and dog cytochrome c using capillary electrophoresis/mass spectrometry with untreated capillary column and basic buffer condition (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 695-697 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Peptide analysis of cytochrome c using capillary electrophoresis/mass spectrometry was demonstrated to be a rapid, sensitive and useful technique for providing information concerning the location of variation. We analyzed tryptic digests of horse, bovine and dog cytochrome c, and compared the peptide analysis results for information concerning amino acid sequences in proteins. The differences in amino acid sequence were confirmed by taking into consideration that all the other fragments are identical in each map. The use of an untreated capillary column with basic buffer condition (water+acetonitrile+(20 g/L) ammonium carbonate (70/20/10), pH 9.2) had a reproducibility of migration times to within about 2%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080906
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  • 96
    Electronic Resource
    Electronic Resource
    Ultramark 1621 as a calibration/reference compound for mass spectrometry. II. Positive- and negative-ion electrospray ionization (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 711-714 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Electrospray ionization of solutions of Ultramark 1621, a commercially available mixture of fluorinated phosphazenes, in solution of 50:23:23:4 v/v of acetonitrile+water+methanol+acetic acid, produced a series of intense singly charged peaks in the m/z range of 900 to ca. 2200 in both positive- and negative-ionization modes. The chemical compositions and accurate masses of ions in both positive- and negative-ion spectra have been reported. An accuracy of approximately 2 ppm has been achieved for the average molecular weight of bovine insulin using Ultramark 1621 peaks as reference standards.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080910
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  • 97
    Electronic Resource
    Electronic Resource
    A curved field reflectron time-of-flight mass spectrometer for the simultaneous focusing of metastable product ions (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 781-785 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The ability to simultaneously focus a wide mass range of metastable fragment ions formed after the initial ionization event in a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer has been made possible by the development of a new type of ion reflector. This coaxially designed time-of-flight instrument employs a modified single stage reflector whose axial voltage gradient rises differentially in order to produce an alignment of energy focal points for product ions. In contrast, product-ion focusing in conventional constant field reflectors occurs over a broad range of distances from the reflectron exit. Approximately 90% of the product-ion mass spectrum can be collected without adjustment, thereby eliminating the need to scan the reflector voltage. Design considerations of the curved field reflectron, its calibration properties and representative metastable spectra of several peptides are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080924
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  • 98
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    Electronic Resource
    Optimization by mass spectrometry of a tryptophan-specific protein cleavage reaction (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 786-790 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Mass spectrometry has been used to define the reaction of BNPS-skatole (3-bromo-3-methyl-2-(o-nitrophenylsulfenyl)indolenine) with selected proteins and peptides, confirming the cleavage of the protein chain at tryptophan residues, characterizing the products, and identifying the side reactions. A short procedure for carrying out the cleavage reaction with minimal side reactions is presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080925
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  • 99
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    Electronic Resource
    Formation of atomic hydrogen in matrix-assisted laser desorption ionization (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 829-832 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Despite the widespread use of matrix-assisted laser desorption ionization, the processes involved in ion formation have yet to be satisfactorily explained. Several protonation processes have been suggested as possible methods for the creation of the analyte ions. In this work the existence of neutral hydrogen atoms in the ablation plume is reported. These are selectively ionized from the ground state through a (2+1) multiphoton resonant excitation scheme. The mass spectra at different delay times between the ablation and the post-ablation-ionization lasers have demonstrated the existence of hydrogen atoms with high velocities in the ablated plume.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290081007
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  • 100
    Electronic Resource
    Electronic Resource
    Characterization of kerogens by matrix-assisted laser desorption ionization mass spectroscopy (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 823-828 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two kerogen samples from shales of different geological age, selected from each of Types I, II and III, have been characterized by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS). A Kratos Kompact MALDI III time-of-flight mass spectrometer equipped with a nitrogen laser operated at 337 nm was used on samples mounted in a matrix of sinapinic acid. The spectrometer was used in linear mode with a mass range up to 270 000 u and an ion extraction voltage of 20 kV. Individual spectra from 50 laser shots at low laser fluence were summed for each spectrum. The present study is a first attempt at characterizing kerogens by MALDI-MS. At low mass (200-500 u) families of peaks consisting of overlapping homologous series of apparently polar compounds have been observed: these peaks appear to be distinct from those due to the matrix material. In higher mass regions of the spectra, continua of masses extending from 1000 u up to around 10 000 u were observed; ions at higher masses were separated to baseline up to masses of 50 000 u. Evidence was found for a relationship between the minimum laser power sufficient for activating the MALDI-ionization process and the geological age of the kerogens; the laser power decreased as the geological age increased. In the case of one kerogen, a high laser fluence was used to generate molecular ions up to the detection limit of the mass spectrometer, in excess of 260 000 u. This paper presents results from a preliminary study of kerogens which requires an in-depth examination of the desorption process in complex mixtures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290081006
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