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  • 1
    Electronic Resource
    Electronic Resource
    The influence of different evaluation techniques on the results of interlaboratory comparisons (1998)
    Springer
    Accreditation and quality assurance 3 (1998), S. 322-327 
    Details
    ISSN: 1432-0517
    Keywords: Key words Interlaboratory comparisons ; Outliers ; Z-scores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The influence of different evaluation techniques on the results of an interlaboratory comparison for the determination of nutrients in ground- and surface water was investigated. The outlier-test procedure was found to influence the interlaboratory standard deviations (SDs), but not the averages. It was shown that even small differences in the numbers of outliers detected can change the SD severely. Comparing the outlier-test procedures of Hampel, Grubbs and Graf-Henning, it was found that Hampel's test detected the most outliers, thus generally resulting in smaller SDs between interlaboratory comparisons. The Graf-Henning test detected the fewest outliers and its application resulted in the highest SDs of the three test procedures investigated. The comparison of different summarising indices, namely the rescaled sum of z-scores, average of absolute z-scores and average deviation showed no comparability. Possibilities to improve the comparability of interlaboratory comparisons and to minimise misunderstandings are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007690050254
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  • 2
    Electronic Resource
    Electronic Resource
    Immuno-affinity columns versus conventional clean-up: a method-comparison study for the determination of zearalenone in corn (1998)
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 241-245 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The efficiency of a modern analytical method employing immuno-affinity columns (IACs) is compared to a well established traditional technique with respect to the determination of zearalenone (ZON) in corn in the μg/kg range. Despite of a constant error of about 4 μg/kg in the examined working range of 10–200 μg/kg, analytical data obtained from the analysis of spiked and naturally contaminated samples showed good correspondence for the compared methods. The performance characteristics of immuno-affinity-chromatography as a new clean-up technique for the determination of ZON in corn is reported for the first time and compared to a conventional clean-up procedure
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050682
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  • 3
    Electronic Resource
    Electronic Resource
    Interlaboratory comparison study for the determination of the Fusarium mycotoxins deoxynivalenol in wheat and zearalenone in maize using different methods (1997)
    Springer
    Fresenius' journal of analytical chemistry 359 (1997), S. 510-515 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Seventeen laboratories from six different countries, using their usual in-house methods, participated in an interlaboratory comparison test for the determination of the Fusarium mycotoxins deoxynivalenol (DON) in wheat and zearalenone (ZON) in maize. The toxins generally were extracted from maize and wheat employing mixtures of water, acidified water with an organic solvent or even pure water (for DON). While participants who used enzyme linked immuno sorbent assays (ELISA) for the determination of DON did not perform any clean-up, various techniques were applied for the purification of raw extracts (e.g. liquid/liquid extraction, solid phase extraction (SPE), immuno affinity chromatography (IAC)). For the final separation/quantification step either high performance liquid chromatography (HPLC) (mostly for ZON), gas chromatography (GC) (for DON) or ELISA were employed by participants. The aim of this study was to obtain information about the state of the art of mycotoxin analysis in cereals and to support a knowledge and experience exchange between the participating laboratories in the field of mycotoxin analysis. For each mycotoxin 5 different sample types were distributed, standard solutions (10.10 μg/ml ZON in methanol, 10.09 μg/ml DON in ethyl acetate), blank materials, spiked samples (75.1 μg/kg and 378.3 μg/kg ZON in maize, 126.2 μg/kg and 2519 μg/kg DON in wheat) and naturally contaminated maize and wheat. Coefficients of variation (CV) between laboratory mean results (outliers excluded) ranged from 6.2 to 27.7% for ZON and from 18.9 to 30.0% for DON. Except for the maize samples spiked at 75.1 μg/kg ZON the overall means (outliers rejected) statistically could not be distinguished from the respective target values. Average recoveries of the reported results ranged from 87.7 to 96.2% for ZON and from 94.2 to 108.5% for DON.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050622
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  • 4
    Electronic Resource
    Electronic Resource
    An enzyme-immunoassay for the detection of the mycotoxin zearalenone by use of yolk antibodies (1998)
    Springer
    Fresenius' journal of analytical chemistry 362 (1998), S. 176-177 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The development of an enzyme-immunoassay (ELISA) for the detection of the Fusarium mycotoxin zearalenone (ZON) is described. In contrast to the common antibody isolation from mammal serum, chicken were immunized in order to isolate specific antibodies from the egg yolk. Five weeks after the start of the immunization a titer of 1:76 000 resulted from three injections without any adverse effects for the animals. Utilizing the indirect competitive assay format ZON could be detected in a concentration range between 10 and 200 μg/L.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051053
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  • 5
    Electronic Resource
    Electronic Resource
    Interlaboratory comparison study for the determination of halogenated hydrocarbons in water (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 660-665 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sixty laboratories of five different countries participated in a large-scale interlaboratory comparison test for the determination of halogenated hydrocarbons in water. Participants used their in-house method with 44 laboratories applying head space GC ECD analysis and 5 using liquid/liquid extraction. A set of two artificially produced samples was prepared; the halogenated hydrocarbons investigated were trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, trichloromethane, tetrachloromethane, 1,1-dichloroethylene, dichloromethane, dibromochloromethane, bromodichloromethane, 1,2-dichloroethane and tribromomethane. The procedure of sample preparation, storage and distribution was monitored by an extensive quality assurance system including homogeneity tests, stability tests, and trend analysis of the submitted data. The analytical results submitted by the participants exhibited RSD values of up to 35% and outlier rates of up to 19%. The percentage of false positive and false negative results was at the highest 12% for selected substances. Recovery rates varying from 86% to 106% proved the correctness of the analytical results submitted by the participants and showed that the procedure developed in this study for sample preparation and distribution is well suited for the performance of large-scale interlaboratory comparison tests of halogenated hydrocarbons in water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051409
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Polymer coated silver halide infrared fibers as sensing devices for chlorinated hydrocarbons in water (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1778-1780 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fiberoptic evanescent wave spectroscopy (FEWS) based on AgClBr fibers and a Fourier transform infrared (FTIR) spectrometer was used for the first time to measure chlorinated hydrocarbons (CH) in water. A minimum detection limit lower than 10 mg/l was achieved by coating the fiber with low density polyethylene (LDPE), which shows reversible enrichment of CH. The response of the sensor to CH diffusion through the polymer layer was analyzed theoretically and the results were found to be in good agreement with the experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108424
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  • 7
    Electronic Resource
    Electronic Resource
    Fiber optic sensor for chlorinated hydrocarbons in water based on infrared fibers and tunable diode lasers (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1868-1870 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel fiber optic evanescent wave spectroscopy (FEWS) system is based on a tunable diode laser (TDL) source, on a polymer-coated AgClBr infrared transmitting fiber, and on a mercury cadmium telluride detector. This system was used for sensing low levels of chlorinated hydrocarbons in water. The detection limit was 100 μg/l (100 ppb), which is an improvement by a factor of 50 in comparison to a similar system that is based on a Fourier transform infrared spectrometer, and the measurement time was reduced by a factor of 3. The TDL-FEWS system shows significant potential for in situ monitoring of ground water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110657
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  • 8
    Electronic Resource
    Electronic Resource
    Simultaneous in-situ trace-analysis of several chlorinated hydrocarbons in water with an IR fiber optical system
    Amsterdam : Elsevier
    Journal of Molecular Structure 294 (1993), S. 1-4 
    Details
    ISSN: 0022-2860
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-2860(93)80300-K
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  • 9
    Electronic Resource
    Electronic Resource
    A system for monitoring & control of processes based on IR fibers and tunable diode lasers
    Amsterdam : Elsevier
    Journal of Molecular Structure 292 (1993), S. 125-132 
    Details
    ISSN: 0022-2860
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-2860(93)80095-D
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Improvement of GC-MS analysis of organochlorine pesticides in sediments by use of a computer-optimized temperature program (1997)
    Springer
    Fresenius' journal of analytical chemistry 359 (1997), S. 293-297 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  A simulation and optimization software program (Pro ezGC® by Analytical Innovations, Inc., Kettering, OH, USA) for GC temperature programs was applied to the analysis of organochlorine pesticides in sediments. By means of this software, the run time of a conventional temperature program derived from trial and error experiments could be reduced to less than a third, achieving at the same time an increased separation efficiency. Finally, 17 organochlorine pesticides could be baseline-resolved on a capillary column in less than 12 min. In addition, a two-fold sensitivity enhancement was achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050576
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