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  • 1985-1989  (5,836)
  • 1840-1849
  • Analytical Chemistry and Spectroscopy  (5,836)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 431-441 
    ISSN: 0886-9383
    Keywords: Resolution of mixtures ; Excitation-emission matrices ; Eigenanalysis ; Wavelength component vectorgram ; Total luminescence spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We consider the problem of resolving the total luminescence spectra of two-component mixtures. Non-negativity of the constituent spectra is commonly used as a criterion to accomplish this resolution, but its application seldom leads to unique answers. Sometimes, the condition must be relaxed because no solution satisfying non-negativity exists. In these cases judgments must be made concerning which parts of the spectra will be allowed to go negative and by how much.The wavelength component vectorgramn (WCV) is presented here as a tool for assisting the experimenter in making these judgments. Even when non-negative resolutions exist, it may happen that resolutions with slight negative elements will more closely match the spectra of the pure constituents. The WCV can also be used as a tool for detecting these cases. The methodology is illustrated with real data from a two-component mixture.
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 453-453 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 451-452 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 443-449 
    ISSN: 0886-9383
    Keywords: Multicomponent analysis ; Iterative refinement ; Simplex method ; Condition numbers ; Linear programming ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concentration estimates of components present in a sample mixture can be obtained using matrix mathematics. In the past, the condition number of the calibration matrix has been used to give an amplification factor by which uncertainties in data can work through to errors in the concentration estimates. This paper explores an additional interpretation of condition numbers with regards to significant figures and rounding errors. A procedure is suggested which will always give the most accurate concentration estimates provided the calibration matrix is not too ill-conditioned. Condition numbers have also been used by analytical chemists to discuss the error bounds for concentration estimates. Unfortunately, only one representative error bound can be approximated for all the components. This paper will show how to compute bounds for individual concentration estimates obtained as solutions to a system of m equations and n unknowns. The procedure is appropriate when calibration data and sample responses are inaccurate.
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989) 
    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
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 21-32 
    ISSN: 0886-9383
    Keywords: Kalman filter ; Multicomponent analysis ; Fluorescence spectral shifts ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of peak shifts on the performance of a Kalman filter multicomponent analysis algorithm has been investigated. A series of Gaussian test systems were employed to characterize the concentration estimation errors and the morphology of the on-line residuals (the innovations sequence). Both forward and reverse filters were used in the generation of the innovations sequences. It was found that the difference between the forward and reverse innovations sequences gave an accurate indication of the direction and magnitude of the peak shift. A series of overlapped two-component systems were also investigated. Again, a correlation between the difference innovations and the degree of the response shift was observed. The behavior of the Kalman filter in fitting the shifted fluorescence emission spectrum of benzo[a]pyrene was also examined. The response for benzo[a]pyrene in cyclohexane solution was compared to that obtained on the surface surface of a reversed phase thin layer chromatography plate. A red shift of 4 nm was detected for the surface spectrum by observing the difference innovations sequence. This approach holds promise for correction of response shifts in multicomponent systems.
    Additional Material: 7 Ill.
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  • 7
    ISSN: 0886-9383
    Keywords: Principal component analysis ; Factor analysis ; Singular value decomposition ; Eigenvalue analysis ; Multivariate analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fisher variance ratio tests are developed for determining (1) the number of statistically significant abstract factors responsible for a data matrix and (2) the significance of target vectors projected into the abstract factor space. F-tests, developed from the viewpoint of vector distributions, are applied to various data sets taken from the chemical literature.
    Additional Material: 3 Tab.
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  • 8
    ISSN: 0886-9383
    Keywords: Parameter estimation ; Cyclic voltammetry ; Quasi-reversible electron transfer reactions ; Cerium (IV) bis(octaethylporphyrinate) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Values of the peak potential, the peak current function and the peak potential difference are extracted from simulated cyclic voltammograms of a quasi-reversible electron transfer reaction. Variations of the feature values are described by empirical functions of the model parameters α (transfer coefficient) and ψ′ (dimensionless form of the heterogeneous electron transfer rate constant ks) using multiple linear regression. These functions are used to determine the system parameters α and ks from test data sets of feature values. The predictive power of the features is discussed. It is shown that several features can be used simultaneously in the analysis. Also, α, ks, the formal potential E0 and the diffusion coefficient D can be estimated simultaneously. Experimental data from the metal-centered one-electron reduction of cerium (IV) bis(octaethylporphyrinate), Ce(OEP)2, are analyzed using the technique, and values of the system parameters for this electrochemical reaction are determined.
    Additional Material: 7 Ill.
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  • 9
    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
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 547-547 
    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
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  • 11
    ISSN: 0886-9383
    Keywords: Evolving factor analysis ; Flow injection analysis ; Self-modeling curve resolution ; Bismuth chloride complexes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Evolving factor analysis is used to estimate the concentration profiles and spectra of Bi3+ and the bismuth chloride complexes BiC12+ through BiCl63- formed by injection of bismuth perchlorate into a flowing stream of 1·0 mol 1-1 HCl. The estimated spectra compare favorably with previously published spectra of the complexes.
    Additional Material: 6 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 463-475 
    ISSN: 0886-9383
    Keywords: Classification ; Discriminant analysis ; Principal components ; Biased estimates ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Classification and regression techniques are among the most used tools by chemometricians. With classification, the two classic methods are discriminant analysis and SIMCA. In this paper we discuss the connection between these two methods and introduce two new ones of the same family: DASCO (discriminant analysis with shrunken covariances) and RDA (regularized discriminant analysis). We demonstrate on both simulated and real data sets that their performance is superior to the old favorites. This is especially true in small-sample/high-dimension settings typical in chemistry.
    Additional Material: 3 Tab.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 493-498 
    ISSN: 0886-9383
    Keywords: Rank annihilation ; Generalized rank annihilation method ; Generalized eigenproblem ; Calibration ; Spectral interferents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved algorithm for the generalized rank annihilation method (GRAM) is presented. GRAM is a method for multicomponent calibration using two-dimensional instruments, such as GC-MS. In this paper an orthonormal base is first computed and used to project the calibration and unknown sample response matrices into a lower-dimensional subspace. The resulting generalized eigenproblem is then solved using the QZ algorithm. The result of these improvements is that GRAM is computationally more stable, particularly in the case where the calibration sample contains chemical constituents not present in the unknown sample and the unknown contains constituents not present in the calibration (the most general case).
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 477-491 
    ISSN: 0886-9383
    Keywords: Principal components analysis ; Cross-validation ; Procrustes rotation ; Variable selection ; Quality control ; Aviation turbine fuel ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Given a set of test criteria that determine a quality specification, the question often arises whether any of the tests are redundant because of intercorrelations Simple selection of tests on the basis of partial correlations with the other tests is rejected on the basis that the random error in the data may be causing spurious correlations.One method is to use cross-validation to define the systematic principal components and examine the correlation structure in this reduced space. It is shown that the presence of principal components dominated by individual tests (‘variable specific’ PCs), which are indicated by cross-validation as being non-systematic, must be taken into account. Having defined the dimensionality, a variable reduction method based on Procrustes rotation selects subsets of tests that preserve the structure of the samples in multivariate space. This is an attractive proposition in the context of maintaining a quality control specification. It is also shown that the variable reduction technique can be used to aid the identification of the true dimensionality of the data space. This approach is applied to a number of routine tests carried out on aviation turbine fuel.
    Additional Material: 10 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 499-509 
    ISSN: 0886-9383
    Keywords: Optimization ; Response surface ; PLS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paper presents a procedure to obtain response surfaces with non-designed data. The method is based on PLS modelling of the expanded X-matrix followed by transformation of the PLS loadings into polynomial coefficients and detection of the co-ordinates of the best response within the experimental domain. The results are presented both graphically and numerically. The procedure is validated on an optimization study of the yield of an organic reaction.
    Additional Material: 4 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 3-20 
    ISSN: 0886-9383
    Keywords: Algorithm ; Computer program ; Data modeling ; Latent variables ; Multiblock ; Multivariate ; PLS ; Process model ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The details of a general multiblock partial least squares (PLS) algorithm based on one originally presented by Wold et al. have been developed and are completely presented. The algorithm can handle most types of relationships between the blocks and constitutes a significant advancement in the modeling of complex chemical systems. The algorithm has been programmed in FORTRAN and has been tested on two simulated multiblock problems, a three-block and a five-block problem. The algorithm combines the score vectors for all blocks predicting a particular block into a new block. This new block is used to predict the predicted block in a manner analogous to the two-block PLS. In a similar manner if one block predicts more than one other block, the score vectors of all predicted blocks are combined to form a new block, which is then predicted by the predictor block as in the two-block PLS. Blocks that both predict and are predicted are treated in such a way that both of these roles can be taken into account when calculating interblock relationships. The results of numerical simulations indicate that the computer program is operating properly and that the multiblock PLS produces meaningful and consistent results.
    Additional Material: 9 Tab.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 97-98 
    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
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989) 
    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
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 100-100 
    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
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 375-395 
    ISSN: 0886-9383
    Keywords: Non-parametric method ; Pattern recognition ; Classification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A non-parametric method for supervised pattern recognition is presented. The method is of the class modelling type, meaning that a classification rule is developed for each class, using the dissimilarities between the objects of the class. The dissimilarities between the objects within a class are related to the distances between all pairs of training objects. As distance metric, a measure is proposed that takes the correlation between the interval-scale variables into account, and that moreover can be used for mixed types of variables. The classification rule is based on the construction of a boundary in the measurement space. For the determination of the class boundary, several strategies are proposed and compared.The performance of the technique is evaluated on the basis of several data sets. Comparison with the class modelling technique UNEQ shows its usefulness for practical application.
    Additional Material: 4 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 409-418 
    ISSN: 0886-9383
    Keywords: Multivariate calibration ; Singular value decomposition ; Regression diagnostics ; Collinearity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Care is required for multicomponent analysis if misleading results are to be avoided. The problem of ill-conditioned calibration matrices is of primary concern. This type of numerical instability is represented as spectral overlap of calibration spectra. Depending on the degree of spectral overlap, the sample concentration estimates can be severely affected. A practical statistical procedure is discussed which tests for the presence of spectral overlap among the pure-component spectra and simultaneously assesses the degree that concentration estimates may be degraded. Guidelines are developed to ascertain how much departure from spectral orthogonality is acceptable.
    Additional Material: 3 Ill.
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  • 22
    ISSN: 0886-9383
    Keywords: NIR reflectance ; Multivariate analysis ; Principal component analysis ; Stepwise multiple linear regression ; Silage quality ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calibrations to predict crude protein (CP) and in vitro dry matter digestibility (IVDMD) in dried grass silage from reflectance data collected at 19 wavelengths on an InfraAlyzer 400R have been developed using stepwise multiple linear (SML) and principal component (PC) regression techniques. A direct comparison of the efficacy of each multivariate technique in this applications has been possible by using identical calibration development and evaluation sample sets. The effect of two data transformation steps prior to PC regression was also investigated. PC regression of raw reflectance data yielded no significant improvement in the standard errors of prediction (SEP) for CP and IVDMD over those obtained by SMLR, viz. 0·61 vs 0·63 and 2·9 vs 3·0 respectively. Computation time for development and evaluation of the PC regression equation was less than for selection of the best SMLR equation, and PCR equations may be more robust. Data transformation to reduce granularity effects prior to PCR did not produce any improvement in predictive accuracy for either IVDMD or CP.
    Additional Material: 5 Ill.
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  • 23
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 453-453 
    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
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 601-608 
    ISSN: 0886-9383
    Keywords: Gas phase flow injection analysis ; Membrane-differentiated analysis ; Multicomponent determinations ; Successive linear regression ; Successive regression in fiduciary region ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A membrane-discriminated gas phase analyzer is proposed for multicomponent determinations. Nitrogen gas flows countercurrent through outer and inner channels in a tube-in-tube arrangement. The only communication between the two channels occurs through a 500 μm aperture covered by a porous PTFE membrane. A mixture of organic compounds (up to four components) is injected into the inner channel by a heated backflushed injector and the sample components diffusing into the outer channel are monitored by a flame ionization detector (FID). A calibration set, consisting of pure components, binary, ternary and quaternary mixtures (a total of 64 samples), provides the known data base: temporal profiles of the FID output as a function of sample composition. Although the overall response behavior is not a linearly additive function of individual analyte concentrations, the use of successive inverse multiple linear regression (while continually altering the choice of the calibration samples considered for the forward regression, on the basis of the most recent values of the predicted unknown sample composition) is shown to yield analytical results for unknown samples that are in good agreement with their true values.
    Additional Material: 3 Ill.
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  • 25
    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
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  • 26
    ISSN: 0886-9383
    Keywords: Fuzzy set theory ; Classification ; Data reduction ; Historical laboratory data ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computer program (FEA) is presented for processing historical laboratory data. It performs on a list of sample entries stored in a laboratory information management system. Using an algorithm which is based on fuzzy set theory, FEA classifies the entries into a limited number of clusters called sample types. The classification is fully user-defined. The program transforms the historical data into a representation which is more suitable for studying the performance of the laboratory or which can be used as preparation for a simulation project.
    Additional Material: 8 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. i 
    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
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  • 28
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 329-342 
    ISSN: 0886-9383
    Keywords: Calibration ; Robust regression ; Iteratively reweighted least squares ; M-estimator ; Monte Carlo simulations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By means of Monte Carlo simulations a comparison has been made between ordinary least squares regression and robust regression. The robust regression procedure is based on the Huber estimate and is computed by means of the iteratively reweighted least squares algorithm. The performance of both procedures has been evaluated for estimation of the parameters of a calibration function and for determination of the concentration of unknown samples. The influence of the distributional characteristics skewness and kurtosis has been studied, and the number of measurements used for constructing the calibration curve has also been taken into account. Under certain conditions robust regression offers an advantage over least squares regression.
    Additional Material: 6 Ill.
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  • 29
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 343-357 
    ISSN: 0886-9383
    Keywords: Principal components regression ; Factorial design ; Hypothesis testing ; Assay validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A validation protocol for multicomponent spectroscopic assays based on principal components regression is described. Factorial design and hypothesis tests are used to establish the linearity and absence of interaction between components in the regression model. Testing considers multiple response variables simultaneously so that correlation between residuals is properly treated. Assay reproducibility and sensitivity to related substances are evaluated.
    Additional Material: 2 Ill.
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  • 30
    ISSN: 0886-9383
    Keywords: Abstract factor analysis ; Target transformation factor analysis ; Signal-to-noise ratios ; Canonical variates analysis ; 13C NMR spectroscopy ; Mixture constituent identification and estimation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of experimental error in analysis of mixture experiments by abstract factor analysis or target transformation factor analysis is considered. The theoretical implications of using signal-to-noise ratios (as weights) or canonical variates analysis to reduce the level of imbedded error in the factor model are examined. The approach is illustrated by application to 13C NMR spectra of lubricant basestock mixtures.
    Additional Material: 5 Ill.
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  • 31
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 32
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 419-429 
    ISSN: 0886-9383
    Keywords: Image analysis ; Chemical imaging ; Multivariate image analysis ; Image analysis for non-imaging techniques ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Images can contain chemical information and many chemical methods can generate image data. For an efficient extraction of chemical data from images, data analysis techniques are necessary. It is a great advantage to be able to work on multivariate images. Many imaging techniques allow the extraction of chemical information. Inorganic analytical chemistry seems to have the longest tradition here, but organic chemistry and biochemistry may soon be catching up. Also large data arrays from non-imaging techniques can be combined with image analysis in a useful way, provided certain conditions are fulfilled.
    Additional Material: 4 Ill.
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  • 33
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    Journal of Chemometrics 3 (1989), S. 537-540 
    ISSN: 0886-9383
    Keywords: Cluster analysis ; Display ; Interlaboratory test ; Ultrametrics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ultrametric inter-object distances found by hierarchical clustering may be used to generate and appropriate constellation of points in a plane. A configuration of points which reproduce the ultrametric distances in a low-dimensional space as closely as possible can be found by Torgerson's method of multidimensional scaling. The resulting display supports the cognition of clusters very well, and for this purpose it seems to be superior to, for instance, the frequently applied principal components display. In certain situations dedrograms are expected to become simpler to interpret when such complementary ‘cluster display’ is also consulted. An example from analytical chemistry is presented.
    Additional Material: 4 Ill.
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  • 34
    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
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  • 35
    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
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  • 36
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 544-545 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 37
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989) 
    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
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  • 38
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 39
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    Journal of Chemometrics 3 (1989) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 40
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    Journal of Chemometrics 3 (1989), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 41
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    Journal of Chemometrics 3 (1989), S. 549-568 
    ISSN: 0886-9383
    Keywords: Multivariate calibration and quantitation ; Factor analysis ; Experimental design ; Sample selection ; Statistical inference ; Wavelength selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One of the major application areas of factor analysis, multivariate calibration and quantitation, is covered in this review. The algorithms, methodologies and applications covered include principal component regression, target transformation factor analysis, singular value decomposition and rank annihilation factor analysis. Many important areas of research having relevance to multivariate calibration and quantitation problems are also covered in this review, including background correction, measurement error, rank determination, cross-validation, figures of merit, detection of invalid samples, experimental design, sample selection, statistical inference and wavelength selection.
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  • 42
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    Journal of Chemometrics 3 (1989), S. 569-577 
    ISSN: 0886-9383
    Keywords: ATP hydrolysis ; Regression analysis ; Model discrimination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data of the hydrolysis of adenosine 5′-triphosphate have been re-evaluated using a computer program that numerically integrates the differential rate equations within a routine that optimizes rate coefficients given a suitable model and concentration versus time data.The model is tested by calculation of Hamilton R-values, the Fisher F-statistic, a sensitivity analysis, the standard errors on the rate coefficients and by constructing contour maps of the objective function versus two rate coefficients.An optimization using only phosphate concentration data cannot distinguish between a model in which adenosine 5′-monophosphate is formed predominantly directly with a molecule of pyrophosphate, and one in which it is formed via adenosine 5′-diphosphate. A more accurate set of rate coefficients is calculated from existing data and the relative importance of the two paths determined.
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  • 43
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    Journal of Chemometrics 3 (1989), S. 579-588 
    ISSN: 0886-9383
    Keywords: Response surface methodology ; Principal components analysis ; Optimization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of multivariate response data by modelling the principal components of the response has been applied to two sets of data. In both cases principal components analysis revealed the relationships among the response variables and exploited them to simplify the problem of modelling and optimizing the multivariate response. The models and optima obtained from the principal components compared favourably with the individual models and simultaneous optima.
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  • 44
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    Journal of Chemometrics 3 (1989), S. 589-600 
    ISSN: 0886-9383
    Keywords: Discriminant analysis ; Principal components ; Canonical variates ; Multivariate analysis of variance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When the number of variables exceeds the number of samples, one method of multivariate discrimination is to use principal components analysis to reduce the dimensionality and then to perform canonical variates analysis (PC-CVA). This paper proposes an alternative approach in which discriminant analysis is carried out by a weighted principal component analysis of the group means (DPCA). This method does not require prior data reduction and produces discriminant factors that are orthogonal in the original data space.The theory and performance of the two methods are compared. Although the individual factors of DPCA are found to be less discriminating than PC-CVA, the overall discrimination, calculated by multivariate analysis of variance, and the predictive value, estimated by the leaving-one-out error rate, are broadly comparable.
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  • 45
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    Journal of Chemometrics 3 (1989), S. 609-609 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 46
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    Journal of Chemometrics 3 (1989), S. 511-527 
    ISSN: 0886-9383
    Keywords: Expert system ; Time series analysis ; Autocorrelation ; Laboratory input signals ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An expert system is presented for automated time series analysis of laboratory sample input signals. The system, AUTOCORR, builds a model of the time series by identifying the processes that are present. These are an uncorrelated random process and, underlying this, possibly one or more of the following: a first-order autoregressive process, a trend and a periodic process. AUTOCORR has a knowledge base of 44 rules and 41 facts for this purpose. The employed shell, INFER, allows the use of algorithmic procedures. Elaborate tests with simulated signals show that AUTOCORR has a very low false positive score and is successful in describing time series for laboratory simulation models.
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  • 47
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    Journal of Chemometrics 3 (1989), S. 529-536 
    ISSN: 0886-9383
    Keywords: Calibration ; Inverse estimator ; Classical estimator ; Mean square error (MSE) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A brief review of the literature on point estimators in linear calibration problems is undertaken. Supportive evidence for the relative merits of the classical and inverse regression models, drawn in general from the classical inferential and Bayesian approaches, is considered and the criteria for comparison of the estimators are discussed with respect to their suitability for certain classes of problems. the performance of the estimators is assessed with respect to determining the current value of ‘x’, the percentage concentration of administered drug levels in blood in this example. No single ‘best’ method of estimation appears to hold for all values of the unknown concentration when performance is assessed by criteria based on the mean square error (MSE). However, the inverse estimator would appear to be superior to the classical for those values of unknown X close to x̄.
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  • 48
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    Journal of Chemometrics 3 (1989), S. 1-1 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
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    Journal of Chemometrics 3 (1989), S. 33-48 
    ISSN: 0886-9383
    Keywords: Higher-order data arrays ; Dimensionality ; Data modelling ; Classification ; Discrimination ; Correlation ; Regression ; Systematics of data analysis ; Opportunities for future developments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A scaffold for detailed understanding of the concept ‘dimensionality’ in data analysis is furnished by a systematic classification of higher-order data array configurations. Three major types of problem formulation in multivariate data analysis can be characterized for relevant data classes: 1data description (intra-class data structure modelling of inter-object and inter-variable relationships)2classification (inter-class discrimination)3correlation, regression (inter-variable relationships).The relationship between these three categories of data analytical problem formulation and the fundamental data array classification is exposed. These relations are augmented to include the general case of data arrays of order R, and R-way data analysis with the use of bilinear projections is presented. Based upon this, some possible directions for the future development of data analysis may be imagined.
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  • 50
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two-sector linked-scan analysis of an unpurified proteolytic digest of a pyruvate decarboxylase enzyme (60 000 Da) has allowed the discovery and assignment of an amino-terminal post-translational modification and processing event. A difference in amino acid sequence from that predicted by a recently published nucleotide sequence has also been found. These results illustrate both the use and considerable potential of linked-scan methods for the analysis of complex biopolymer mixtures.
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  • 51
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 68-71 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Product ion spectra derived from molecule ions as the precursor ions for 14 alkylbenzenes have been studied under electron ionization and methane chemical ionization. The data have provided a satisfactory screening method for both detection and confirmation of such compounds at low parts per million levels.
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  • 52
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 138-140 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Product-ion spectra derived from both protonated and hydride-abstracted molecules of long chain esters have revealed an unusual homologous series of ions which suggest a cyclization mechanism to form stabilized bicyclodecenes or bicyclononenes.
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  • 53
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 155-159 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new time-of-flight mass analyser compatible with conventional continuous ionization methods is described. A mass resolution at m/z 2000 of m/Δm〉2000 (50% valley) is predicted for the instrument which is presently being prototyped. Sensitivity advantages over scanning instruments are also predicted for this instrument.
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  • 54
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 170-170 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 55
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 79-84 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Capabilities of high resolution chromatography/tandem mass spectrometry for quantitation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans have been investigated with a hybrid instrument. Selected-transition monitoring procedures, collision energy and collision gases have been optimized for maximum sensitivity. The results are compared with those obtained by high resolution chromatography/high resolution mass spectrometry.
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  • 56
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    Rapid Communications in Mass Spectrometry 3 (1989), S. ii 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 57
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An on-line coaxial continuous-flow capillary-zone electrophoresis/fast-atom bombardment mass spectrometry (CZE/FAB-MS) interface is described. This interface is shown to be capable of acquiring mass spectra in an online fashion from low femtomole amounts of peptides while maintaining high (hundreds of thousands of plates) electrophoretic separation efficiencies. Active electrophoretic transport of the analytes directly to the FAB probe tip obviates the need for a transfer line from the end of the CZE capillary to this point, and thereby precludes the zone broadening that would otherwise occur both within such a transfer line and in the connections between the CZE column and the transfer line. The capability of acquiring an on-line tandem mass spectrometry (MS/MS) spectrum of an electrophoretically separated analyte using this interface is also demonstrated.
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  • 58
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    Rapid Communications in Mass Spectrometry 3 (1989), S. iii 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 59
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 60
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 212-216 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Collisionally activated decomposition spectra derived from normal nucleosides and nucleotides have been studied using a four-sector tandem mass spectrometer. The selectivity for a precursor ion has been improved by the use of the first two sectors as a double-focusing mass spectrometer, and the mass resolution of daughter spectra has been enhanced using the next two sectors as a second double-focusing mass spectrometer. Reliable and reproducible data with respect to the structure of nucleosides and nucleotides have been obtained.
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  • 61
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 222-224 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The fragmentation of some carbamoyl- and thiocarbamoylcyclohexanones under electron ionization has been investigated by means of high- and low-resolution mass spectrometry and deuterium labelling. Some characteristic fragmentation processes observed in the mass spectra of thiocarbamoylcyclohexanones indicate that both keto and enol forms of their molecular ions exist in the gas phase. The fragmentation data for carbamoylcyclohexanone show that the keto form is largely predominant in the keto-enol tautomeric equilibrium.
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  • 62
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 217-221 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Sequential daughter-ion-scanning analyses of small peptides have been performed using a hybrid tandem instrument of BEqQ configuration. Precursor ions are selected by B and allowed or induced (by high-energy collisional activation) to decompose in the region preceding E. Decoupling of E from the accelerating voltage permits the selection of the first-generation daughter ion whilst retaining appropriate float voltages for the quadrupole assemblies. The daughter ion selected by E is further subjected to low-energy collisional-activation dissociation (CAD) in q and the fragment-ion spectrum is obtained by scanning Q. The sequential daughter-ion-scanning technique has been used to establish that ‘internal’ fragments of the types, (AY′) and (BY′), are formed via initial Y-type cleavage. Fragmentation of a protonated peptide (angiotensin III) by loss of the C-terminal amino acid residue, yielding a (Bn′ + OH) ion, is reported for the first time. This process is analogous to that previously described for metal-cationized peptides.
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  • 63
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 230-232 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Chemotaxonomic studies are frequently limited by the volume of data obtained and the difficulty of reducing this to statistically interpretable results. This paper describes the use of a straightforward procedure for relating the pattern of occurrence of sterols in fungi, analysed by mass spectrometry, to their classification.
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  • 64
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 238-240 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Pyrolysis-desorption/chemical-ionisation mass spectrometry (PyD/CIMS), using ammonia as ionization gas, was employed to investigate the influence of potassium hydroxide on the pyrolytic behaviour of glucans. The mass spectrum of native amylose, a 1 → 4 linked α-D-glucan, revealed an ion series pointing to desorption of intact 1,6-anhydro-oligosaccharides. Ions indicating oligomers up to the nonamer were observed. Addition of trace amounts of potassium hydroxide to amylose resulted in reduction in the size of the 1,6-anhydro-oligosaccharide ions and a simultaneous increase of ions resulting from ring rearrangements. Larger amounts of potassium hydroxide led to a complete loss of mass spectral information at the oligomer level.Similar mass spectrometric distributions in the PyD/CIMS data of a potassium hydroxide extracted tobacco fraction clearly reveal that alkali remnants must be present in this sample, which severly reduce the mass spectrometric information from polysaccharide oligomers. It is important to evaluate the role of inorganics on the thermal activation and subsequent fragmentation of biopolymers in PyD/CIMS experiments.
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 126-126 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 66
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    Rapid Communications in Mass Spectrometry 3 (1989) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 67
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    Rapid Communications in Mass Spectrometry 3 (1989), S. ii 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Rapid Communications in Mass Spectrometry 3 (1989) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 69
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 135-137 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A fully automated computer-controlled system was used to generate series of different linked scans at constant B2E and constant neutral loss in the second field-free region. This system has been shown to be suitable for deriving the amino acid sequence of oligopeptides.
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  • 70
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 140-144 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Lens and ion trajectory simulation programs, such as the popular program SIMION, which employ potential array relaxation methods, are very useful in designing and modifying ion lens systems. Unfortunately, these programs cannot simulate lenses of certain geometries such as quadrupoles. Several approaches for portraying static DC quadrupole lenses accurately in such programs have been investigated. These include user programming, an option in the latest version of SIMION, and array modification. The most convenient and accurate method involves modifications to the lens arrays employing relaxation techniques similar to those used in SIMION itself. These have been incorporated into a self-contained computer program named QREFINE, which is available to interested parties.
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  • 71
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 145-150 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Ion-spray mass spectrometry was investigated for the analysis of three marine neurotoxins: domoic acid, saxitoxin and tetrodotoxin. All three compounds gave positive-ion spectra with abundant ions of protonated molecules and no significant fragmentation. Domoic acid gave a negative-ion spectrum with a strong [M-H]-ion. Tandem mass spectrometry provided useful fragment-ion spectra for all compounds. Detection limits for flow injection analyses with selected-ion monitoring were determined to be 30 pg for saxitoxin, 100 pg for domoic acid and 200 pg for tetrodotoxin. Combining liquid chromatography with ion-spray mass spectrometry allowed the determination of domoic acid and some of its isomers in toxic shellfish tissue extracts.
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 151-152 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Ab initio calculations indicate that the ion [ONCO]- is linear, whereas [HNNCO]- is effectively coplanar. The ions may be formed by collisional activation of deprotonated hydroxy and aminocarbamates. The characteristic fragmentations of [ONCO]- and [HNNOO]- are losses of O and NH respectively.
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  • 73
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 153-155 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new sensitive and precise method for the determination of the isotopic enrichment of [6, 6-D2] ghicose and concentration of glucose in plasma microsamples (20 μL) has been developed. Glucose was extracted from plasma samples by anion-cation column-exchange with absolute ethanol, derivatized as 1,2:3,5-bis(butylboronate)-6-acetyl-α-D-glucofuranose, and analysed by capillary gas chromatography/ammonia chemical-ionization mass spectrometry. This method gives a better reproducibility and precision (variation coefficient below 1%) than methods using isobutane chemical ionization.Stable isotopes are being used increasingly to investigate energy metabolism in vivo. Recent work has involved the development of methodologies, especially mass spectrometry, to perform tracer experiments using the stable isotopes 2H, 13C, or 15N.1-4 Chemical-ionization mass spectrometry is extensively used for the analysis of isotopically labelled amino acids.2-6In neonates and chidren, „true“ glucose production can be measured by the continuous infusion of the stable isotopically labelled tracer 6,6-dideutero-glucose (6,6-D2-glucose), and analytical measurement is performed using gas chromatography/electron-ionization mass spectrometry (GC/EIMS).7Herein, we present a new, simple and sensitive method for the determination of the isotopic enrichment of [6,6-D2]glucose and measurement of the concentration of glucose in plasma microsamples (20 μL), based on the use of capillary gas-chromatography/ammonia chemical-ionization mass spectrometry of 1,2:3,5-bis(butylboronate)-6-acetyl-α-D-glucofuranose.
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 160-164 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Electrospray ionization generates multiply charged peptide molecular ions which are efficiently dissociated by collision with a neutral gas to provide sequence-specific daughter ions. The scope for application of this phenomenon is illustrated by the nearly complete sequencing of melittin (relative molecular mass (Mr) 2846.5) employing a tandem quadrupole mass spectrometer having a mass limit of m/z 1400.
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 165-170 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 76
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    Rapid Communications in Mass Spectrometry 3 (1989), S. i 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 77
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 300-301 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A technique for the simplification of fast-atom bombardment (FAB) spectra of polysulfonic acids, especially azo dyes complicated by sodium, is discussed. The sodium may be present as the sulfonate salt or the salt may be formed during FAB analysis from impurities present in the sample. The incorporated sodium as well as other impurities which may be present in commercial samples are removed by means of a simple cationic-exchange-resin procedure, yielding simplified and unambiguous FAB spectra of the sodium-free material.
    Additional Material: 4 Ill.
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  • 78
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Quantitation of cyclic nucleotide phosphodiesterase activity by means of fast-atom bombardment (FAB) mass spectrometry with mass-analysed ion kinetic energy (MIKE) spectrum scanning is described. Characteristic peaks of the substrate, cyclic AMP, and product, AMP, were identified in positive-ion FAB mass spectra and MIKE scans of the protonated molecules. By spiking enzyme incubates with known quantities of cyclic AMP and AMP and measuring peak heights in the MIKE spectra of both spiked and unspiked samples, the concentrations of cyclic AMP and AMP in solution at the end of a series of enzyme incubations have been estimated. From the data obtained the Km and Vmax of the enzymes were calculated as 181 μM and 28.6 nmol/min respectively, showing excellent agreement with values of the Michaelis constant, Km=205 μM and the maximum velocity Vmax=33.2 nmol/min obtained by radioactive assay.
    Additional Material: 4 Ill.
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  • 79
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fast-atom bombardment mass spectrometry of a synthetic renin substrate decapeptide (Pro-His-Pro-Phe-His-Leu-Val-Ile-His-D-Lys) indicated the presence of several of side-products, including a component 12 Da higher in mass. Low-energy collisionally activated decomposition analyses were performed using a hybrid tanden, instrument and demonstrated that the heavier side product had two components, in which the structural modification was either at the N- or the C-terminus. Additional analyses of the N-acetyl derivative indicated that for each component the strucutrual modification blcoked a site of N-acetylation. It is suggested that the formation of these side products is attributable to the generation of formaldehyde, during removal of the histidine protecting group (benzyloxymethyl), which reacts with the N-terminus of the peptide to give an imidazolidinone structure or with the D-lysine ε-amine group to yield an imine. While the precise genesis of the side-products remains speculative, it is clear that the combined strategy of derivatization and tandem mass spectrometry has allowed structural conclusions concerning individual components of an isobaric mixture.
    Additional Material: 5 Ill.
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  • 80
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 197-202 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: 2-Acylcyclohexane-1,3-diones and their 4-hydroxy analogues were analysed by gas chromatography/mass spectrometry. Fragmentation pathways for the formation of diagnostic ions are suggested.
    Additional Material: 7 Ill.
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  • 81
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    Rapid Communications in Mass Spectrometry 3 (1989), S. i 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 82
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fast-atom bombardment, thermal ionization and inductively coupled plasma mass spectrometry are contrasted in comparative measurements of 64Zn/67Zn isotope ratios on samples isolated in the course of a human mineral-nutrition experiment. The data are evaluated with reference to the precision normally required in enriched stable-isotope mineral-nutrition studies, and the convenience of the mass spectrometric techniques is also compared.
    Additional Material: 1 Tab.
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  • 83
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    Rapid Communications in Mass Spectrometry 3 (1989), S. iii 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 84
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    Rapid Communications in Mass Spectrometry 3 (1989) 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 85
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 207-211 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Knudsen cell mass spectrometric measurements are reported on the composition of vapour over solid and fused NaI, CsI, HoI3, DyI3, (NaI + HoI3), (NaI + DyI3, (CsI + HoI3) and (CsI + DyI3 systems. For the determination of evaporation thermodynamics, the assignment of the essential ions to their neutral precursors was carried out by determining ionization efficiency curves. Due to the spread in electron energy, the linear extrapolation and vanishing current methods, which are generally used in high temperature mass spectrometry for evaluation of efficiency curves, could be used with limitations only. The analytical energy-distribution difference method was used to determine the fine structure of the ionization efficiency curves. The method uncovered relationships between the detected ions and neutral vapour-phase species, and served to determine thermodynamic data with improved precision.
    Additional Material: 6 Ill.
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  • 86
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 225-229 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Secondary-ion mass spectrometry, using Cs+ ion bombardment of solid and liquid matrices, has been implemented on a quadrupole ion trap. Tetraalkylammonium cations and protonated peptides, generated in an external source using a pulsed primary-ion beam, are injected into the ion trap where they are decelerated and trapped in the course of collisions with the helium bath gas. The contents of the trap are then examined by recording a mass spectrum using the mass-selective instability scan. To improve performance in the examination of these trapped ions, the technique of axial modulation is used to cause resonance ejection of ions from the trap during the mass-analysis step. The supplementary AC voltage applied to the end-caps causes resonant ejection of ions at qz values below those which correspond to the normal stability limit. This is demonstrated to increase the mass limit of a commercial ion trap from 650 Da to approximately 1300 Da with no loss in resolution or sensitivity, and to more than 20 000 Da at reduced sensitivity.
    Additional Material: 7 Ill.
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  • 87
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 233-237 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The production of high-mass quasimolecular ions from proteins by matrix-assisted ultraviolet laser desorption is described. A simple time-of-fight system using a Q-switched frequency-quadrupled Nd-YAG laser to desorb protein molecules is shown to have a mass range of up to 116 000 u by the observation of intact, singly charged quasimolecular ions from 700 fmol of β-galactosidase subunit (mol.wt = 116 336 Da). Both positive- and negative-ion spectra of proteins are shown. Four new matrix materials, with properties as good as or better than nicotinic acid, are described. A mass resolution of approximately 500 (full width at half maximum definition) is demonstrated for proteins with mol.wt 〈 20 000 Da. Product species, formed by fast photochemical reactions in the matrix, are observed to form adduct ions with protein molecules. These adduct ions are a significant cause of the observed broadness of protein quasimolecular ion peaks. The practical physical considerations in detection of large-mass quasimolecular ions from laser desorption, such as detector overloading, are discussed.
    Additional Material: 5 Ill.
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  • 88
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 244-246 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 3 Tab.
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  • 89
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 241-243 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The ion trap detector (ITD) is effective in the analysis of terpenoic mixtures from essential oils. ITD spectra are compared in library searches with spectra from a quadrupole mass spectrometer. ITD generally leads to lower FIT values, although its efficiency in terms of structural identification is comparable to that of quadrupolar systems.
    Additional Material: 1 Ill.
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  • 90
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    Rapid Communications in Mass Spectrometry 3 (1989), S. i 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 91
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    Rapid Communications in Mass Spectrometry 3 (1989), S. ii 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 92
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 255-258 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The mass spectra of a number of compounds have been measured using a novel electrospray interface to magnetic sector instruments. The performance of the interface, combined here with both single- and double-focusing spectrometers, is compared with existing interfaces to quadrupole instruments.
    Additional Material: 12 Ill.
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  • 93
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 273-275 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Labelled derivatives of the 5-methyl-2-hexanone radical cation have permitted the elucidation of the origin of the main fragment ion [M—C2H5]+ and the characterization of different rearrangement processes.
    Additional Material: 1 Tab.
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  • 94
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The metastable ion spectra of the [M + Na]+ ions generated by fast-atom bombardment of sodium chloride containing oligopeptide samples are shown to produce an intense sequence ion from which the identity of the C-terminal amino acid can be readily established.
    Additional Material: 4 Ill.
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  • 95
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 281-281 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 96
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    Rapid Communications in Mass Spectrometry 3 (1989), S. ii 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 97
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    Rapid Communications in Mass Spectrometry 3 (1989) 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 98
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Crystalline Ce(C5H7O2)4 has been synthesized directly from the reaction of hydrated cerium(IV) oxide with acetylacetone, (C5H8O2), and its electron-ionization (EI) mass spectrom is reported. The compound exists as a monomer (mass 536) in the gaseous state. The mass spectrum, like those of M(C5H7O2)4 (M = Zr or Th) and CeL4 (L = fluorinated β-diketonate), shows the dominant ion signal to be due to the [Ce(C5H7O2)3]+ ion that arises from the loss of one C5H7O2 from the molecular ion. An internal electron-transfer affords [Ce(C5H7O2)3]+·. Fragmentation of [Ce(C5H7O2)3]+· to [Ce(C5H7O2)2]+ is similar to that observed for the tris-chelates of trivalent transition metals and La(C5H7O2)3. The ion [Ce(C5H7O2)2]+ ultimately breaks down to [CeO]+ through the sequential loss of three even-electron neutral species, CH3COCHCCH2, H2O and CH3COCHCCH2 without invoking any further reduction of the Ce centre. Mechanisms are given for the loss of the three even-electron species from the bis(acetylacetonato)cerium(III) ion fragment. Theoretical simulations of patterns of the fragment ions [Ce(C5H7O2)3]+·, [Ce(C5H7O2)2]+·, and [Ce(C5H7O2)OH]+ have been made and compared with those of the corresponding experimental results in support of the suggested mode of fragmentation.
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  • 99
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 320-322 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: 1-(2-nitrophenyl)benzotriazole loses nitrogen upon electron ionization. This reaction is followed by a Wolff-type ring contraction to give cyclopentadienylidene methanimine ions which undergo an internal oxidation process producing ionized cyclopentadienone.
    Additional Material: 2 Ill.
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  • 100
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    Rapid Communications in Mass Spectrometry 3 (1989), S. i 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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