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  • General Chemistry  (77.717)
  • Analytical Chemistry and Spectroscopy  (25.033)
  • GEOPHYSICS  (21.936)
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  • 101
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993) 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070101
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  • 102
    Digitale Medien
    Digitale Medien
    Compression of nth-order data arrays by B-splines. Part 1: Theory (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 61-73 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Compression ; Multivariate analysis ; B-splines ; Maximum entropy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For efficient handling of very large data arrays, pretreatment by compression is mandatory. In the present paper B-spline methods are described as good candidates for such data array compression. The mathematical relation between the maximum entropy method for compression of data tables and the B-spline of zeroth degree is described together with the generalization of B-spline compression to nth-order data array tables in matrix and tensor algebra.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070105
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  • 103
    Digitale Medien
    Digitale Medien
    Investigation of copper(II)-Ethylenediaminetetraacetate complexation by window factor analysis of ultraviolet spectraPresented at the Eastern Analytical Symposium in Somerset, NJ on 14 November 1992 (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 89-98 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Factor analysis ; Window factor analysis ; Multicomponent analysis ; Ultraviolet spectroscopy ; Cu(II) complexes ; Ethylenediaminetetraacetic acid ; EDTA ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Window factor analysis (WFA) is a self-modeling chemometric technique for obtaining the concentration profiles of components from evolutionary processes such as chromotography, titration and reaction kinetics. By specifying the ‘window’, i.e. the region along the evolutionary axis indigenous to a component, the concentration profile of the component can be obtained without recourse to any information concerning the other components. Mathematical expressions required to perform such computations are derived. The method is applied to the investigation of copper(II) complexation with ethylenediaminetetraacetate (EDTA) by recording and factor analyzing the ultraviolet spectra of aqueous solutions containing a fixed amount of the disodium salt of EDTA and varying amounts of CuCl2. Evidence for four different species of EDTA is obtained. Clues concerning the stoichiometry of the species are garnered from the concentration profiles.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070203
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  • 104
    Digitale Medien
    Digitale Medien
    Short communication Classification methods for multivariate quality parameters (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 131-142 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Classification ; Discriminant analysis ; Class modeling ; Specification limits ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: There are many chemical products where product conformity is decided upon by qualitative human judgements of overall product quality. Nowadays, quantitative instrumentally determined quality parameters become available which are intended to replace such qualitative judgements by means of automatic decision rules using multivariate specification limits. Six classification methods to derive such limits are compared in terms of their power to predict corresponding human judgemets on overall color conformity of 17 dyestuffs based on historical quality data. Standard statistical classification methods turned out to be unacceptable for the routine generation of decision rules because of the frequent distinct suboptimality of their predictive power. Instead, a simple non-statistical classification method utilizing a priori knowledge about the underlying data structure yielded uniformly satisfactory decision rules.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070206
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  • 105
    Digitale Medien
    Digitale Medien
    A global perspective on multivariate calibration methods (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 153-163 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Generalized inverse ; K-matrix analysis ; P-matrix analysis ; Least squares ; Principal component regression ; Partial least squares ; Continuum regression ; Beer's law ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper consists of two distinct but related parts. In the first part a geometric theory of generalized inverses is presented and a methodology based on this theory is developed and applied to solve the K-matrix and P-matrix forms of Beer's law. It is shown that most currently accepted and practiced methods for solving these forms of Beer's law are just special cases of this geometric theory of generalized inverses. In addition, this geometric theory is used to explain why the current methods work and why they fail.In the second part a general methodology that includes as special cases least squares, principal component regression, partial least squares 1 and 2, continuum regression plus a variety of other described and undescribed methodologies is presented and then applied to solve the P-matrix formulation of Beer's law. This general methodology, like the first, is also geometric in nature and relies on an understanding of projections.The main emphasis of this paper is one of perspective, which, if understood, provides the proper foundation for answering the general but extremely hard and possibly unanswerable question “what is the best method?”.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070303
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  • 106
    Digitale Medien
    Digitale Medien
    Detecting and adjusting for non-linearities in calibration of near-infrared data using principal components (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 195-212 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Calibration ; Non-linearity ; Principal components ; Stein estimate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new regression method for non-linear near-infrared spectroscopic data is proposed. The technique is based on a model which is linear in the principal components and simple functions (squares and products) of them. Added variable plots are used to determine which squares and products to incorporate into the model. The regression coefficients are estimated by a Stein estimate which shrinks towards the estimate determined by the first several principal components and the selected non-linear terms. The technique is not computationally intensive and is appropriate for routine predictions of chemical concentrations. The method is tested on three data sets and in all cases gives more accurate predictions than does linear principal components regression.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070306
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  • 107
    Digitale Medien
    Digitale Medien
    Non-linear mapping for structure-activity and structure-property modelling (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 227-242 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Non-linear mapping ; Graphical methods ; SAR ; SPR ; Quality of representation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: From a review of the theoretical aspects of non-linear mapping and the different algorithms available in the literature, the methodological and practical problems linked to the use of this multivariate method in structure-activity and structure-property relationship studies are underlined. Useful tools for the graphical display of the outputs and the interpretation of the obtained clusters are presented. Statistical parameters estimating the quality of the graphical representation of each individual are also introduced. An example of application on a data matrix of 37 acaricides described by four physicochemical descriptors (π, F, R, MR) is presented.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070402
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  • 108
    Digitale Medien
    Digitale Medien
    A test of significance for partial least squares regression (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 291-304 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Partial least squares ; Monte Carlo methods ; Cross validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Partial least squares (PLS) regression is a commonly used statistical technique for performing multivariate calibration, especially in situations where there are more variables than samples. Choosing the number of factors to include in a model is a decision that all users of PLS must make, but is complicated by the large number of empirical tests available. In most instances predictive ability is the most desired property of a PLS model and so interest has centred on making this choice based on an internal validation process. A popular approach is the calculation of a cross-validated r2 to gauge how much variance in the dependent variable can be explained from leave-one-out predictions. Using Monte Carlo simulations for different sizes of data set, the influence of chance effects on the cross-validation process is investigated. The results are presented as tables of critical values which are compared against the values of cross-validated r2 obtained from the user's own data set. This gives a formal test for predictive ability of a PLS model with a given number of dimensions.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070407
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  • 109
    Digitale Medien
    Digitale Medien
    Optimization in organic synthesis. An approach to obtaining kinetic information by sequential response surface modelling. Outline of the principles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 341-367 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Reaction kinetics ; Initial rate ; Kinetic order ; Response surface modelling ; Canonical analysis ; Organic synthesis ; Optimization ; Reaction mechanisms ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method is presented by which it is possible to estimate the initial rate of chemical reactions when the experimental conditions are varied according to a response surface design. The method is intended as a complementary method for analysing data obtained from experiments in synthetic chemistry when the objective is to optimize the yield of the reaction.Data obtained by simulations have been used to develop the method. From the simulated reactions it is shown that sequential analysis of the chemical yield of the reaction makes it possible to estimate models which describe how the parameters of the response surface of the yield vary over time. The derivatives of these time functions of the response surface parameters can be used to define a rate function which describes how the variations in the experimental conditions influence the rate of the reaction.It is shown how such rate functions can be used to afford reasonable estimates of the initial rates of the reaction. The initial reaction rates thus estimated can be used to determine the kinetic order of the reactants and also to provide estimates of the activation energy of the reaction.A thorough discussion of how canonical analysis of the rate function may assist in the elucidation of reaction mechanisms is given.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070503
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  • 110
    Digitale Medien
    Digitale Medien
    Multivariate selection of variables in industrial quality control: Optimizing aviation fuel final control (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 427-438 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Quality control ; Kerosene ; Variable reduction ; Cross-validation ; Variable selection ; Procrustes rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper deals with a typical question encountered in all industrial analytical laboratories: are all the tests performed in the laboratory to characterize the final product really necessary? In this work the cross-validation technique, Procrustes rotation techniques and statistical variable selection have been used to reduce the 26 initial British Petroleum and ASTM kerosene specification test to ten ‘essential’ ones. Statistical as well as chemical considerations were used to select the optimum subset of original variables to be retained from all the possible ones.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070507
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  • 111
    Digitale Medien
    Digitale Medien
    EDITORIAL (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 453-454 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070602
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  • 112
    Digitale Medien
    Digitale Medien
    Robust principal component analysis by projection pursuit (1993)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 527-541 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Principal component analysis ; Projection pursuit ; Simulated annealing algorithm ; Robust statistics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Principal component analysis (PCA) is a widely used technique in chemometrics. The classical PCA method is, unfortunately, non-robust, since the variance is adopted as the objective function. In this paper, projection pursuit (PP) is used to carry out PCA with a criterion which is more robust than the variance. In addition, the generalized simulated annealing (GSA) algorithm is introduced as an optimization procedure in the process of PP calculation to guarantee the global optimum. The results for simulated data sets show that PCA via PP is resistant to the deviation of the error distribution from the normal one. The method is especially recommended for use in cases with possible outlier(s) existing in the data.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180070606
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  • 113
    Digitale Medien
    Digitale Medien
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080101
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  • 114
    Digitale Medien
    Digitale Medien
    Bootstrap accuracy for non-linear regression models (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 37-44 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Bootstrap ; Confidence interval ; Non-linear regression ; Monte Carlo methods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Non-linear regression models describing the toxicity of a mixture of rotenone and pyrethrins as an insecticide, the catalytic dehydration of n-hexyl alcohol and the Michaelis-Menten model for characterizing reaction rates in enzyme systems will be used to illustrate the accuracy of bootstrap methods in non-linear regression. Classical and bootstrap confidence intervals for the parameter estimates will be presented.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080105
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  • 115
    Digitale Medien
    Digitale Medien
    SCAN (Software for Chemometric Analysis), available from JerII, Inc., North American Office: 790 Esplanada, Stanford, CA 94305, U.S.A. (telephone (415) 856-3401); European Office: via V. Pisani 13, 20124 Milano, Italy (telephone 39-2-26603247). Price US$ 3000 commercial, US$ 2000 academic (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 95-96 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080109
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  • 116
    Digitale Medien
    Digitale Medien
    Announcement (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 102-102 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080113
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  • 117
    Digitale Medien
    Digitale Medien
    A PLS kernel algorithm for data sets with many variables and fewer objects. Part 1: Theory and algorithm (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 111-125 
    Details
    ISSN: 0886-9383
    Schlagwort(e): PLS regression algorithm ; Kernel ; Many-variable data sets ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A fast PLS regression algorithm dealing with large data matrices with many variables (K) and fewer objects (N) is presented For such data matrices the classical algorithm is computer-intensive and memory-demanding. Recently, Lindgren et al. (J. Chemometrics, 7, 45-49 (1993)) developed a quick and efficient kernel algorithm for the case with many objects and few variables. The present paper is focused on the opposite case, i.e. many variables and fewer objects. A kernel algorithm is presented based on eigenvectors to the ‘kernel’ matrix XX TYYT, which is a square, non-symmetric matrix of size N × N, where N is the number of objects. Using the kernel matrix and the association matrices XXT (N × N) and YYT (N × N), it is possible to calculate all score and loading vectors and hence conduct a complete PLS regression including diagnostics such as R2. This is done without returning to the original data matrices X and Y. The algorithm is presented in equation form, with proofs of some new properties and as MATLAB code.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080204
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  • 118
    Digitale Medien
    Digitale Medien
    Comments on the PLS kernel algorithm (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 169-174 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Kernel algorithm ; PLS ; SVD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Lindgren et al. (J. Chemometrics, 7, 45-49 (1993)) published a so-called kernel algorithm for PLS regression of Y against X when the number of objects is very large. The algorithm is based solely on deflation of the cross-product matrices XTX, YTY and XTY. The algorithm is now described in a shorter and more transparent way and compared with a similar algorithm for the singular value decomposition of XTY.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080208
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  • 119
    Digitale Medien
    Digitale Medien
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994) 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080301
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  • 120
    Digitale Medien
    Digitale Medien
    Evaluation and control of measurements, John Mandel, Quality and Reliability Series, Marcel Dekker, New York, 1991, ISBN O-8247-8531-2, xi + 249 pp. £58.77 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 241-241 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080306
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  • 121
    Digitale Medien
    Digitale Medien
    Generalized rank annihilation method. III: Practical implementation (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 273-285 
    Details
    ISSN: 0886-9383
    Schlagwort(e): GRAM ; Least-squares problem ; Eigenvalue problem ; NIPALS ; Performance index ; Condition number ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this paper we discuss the practical implementation of the generalized rank annihilation method (GRAM). The practical implementation comes down to developing a computer program where two critical steps can be distinguished: the construction of the factor space and the oblique rotation of the factors. The construction of the factor space is a least-squares (LS) problem solved by singular value decomposition (SVD), whereas the rotation of the factors is brought about by solving an eigenvalue problem. In the past several formulations for GRAM have been published. The differences essentially come down to solving either a standard eigenvalue problem or a generalized eigenvalue problem. The first objective of this paper is to discuss the numerical stability of the algorithms resulting from these formulations. It is found that the generalized eigenvalue problem is only to be preferred if the construction of the factor space is not performed with maximum precision. This is demonstrated for the case where the dominant factors are calculated by the non-linear iterative partial least-squares (NIPALS) algorithm. Several performance measures are proposed to investigate the numerical accuracy of the computed solution. The previously derived bias and variance are proposed to estimate the number of physically significant digits in the computed solution. The second objective of this paper is to discuss the relevance of theoretical considerations for application of GRAM in the presence of model errors.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080406
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  • 122
    Digitale Medien
    Digitale Medien
    Comments on ‘Data analysis with minimal assumptions’ (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 299-301 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080411
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  • 123
    Digitale Medien
    Digitale Medien
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080502
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  • 124
    Digitale Medien
    Digitale Medien
    Interactive variable selection (IVS) for PLS. Part 1: Theory and algorithms (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 349-363 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Variable selection ; PLS ; Calibration ; Modelling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A modified PLS algorithm is introduced with the goal of achieving improved prediction ability. The method, denoted IVS-PLS, is based on dimension-wise selective reweighting of single elements in the PLS weight vector w. Cross-validation, a criterion for the estimation of predictive quality, is used for guiding the selection procedure in the modelling stage. A threshold that controls the size of the selected values in w is put inside a cross-validation loop. This loop is repeated for each dimension and the results are interpreted graphically. The manipulation of w leads to rotation of the classical PLS solution. The results of IVS-PLS are different from simply selecting X-variables prior to modelling. The theory is explained and the algorithm is demonstrated for a simulated data set with 200 variables and 40 objects, representing a typical spectral calibration situation with four analytes. Improvements of up to 70% in external PRESS over the classical PLS algorithm are shown to be possible.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080505
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  • 125
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    Digitale Medien
    Diary (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080602
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  • 126
    Digitale Medien
    Digitale Medien
    A frequency deconvolution procedure using a conjugate gradient minimization method with suitable constraints (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 409-421 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Deconvolution ; FT-IR spectroscopy ; Protein conformations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In a variety of spectroscopic techniques the fundamental problem exists of determination of the individual spectral components, intrinsically overlapped in the measured spectrum. This is a typical deconvolution problem and several methods and techniques have been proposed for its solution in the technical literature, but suggestions of new approaches are still of interest. A new deconvolution procedure is presented here based on the use of the conjugate gradient minimization algorithm with the addition of sutiable constraints directly obtained by the application to the measured spectrum of the second-derivative operator or more sophisticated resolution enhancement procedures. Since in the examined case deconvolution essentially requires the minimization of a non-convex function, the use of such constraints is extremely important to supply suitable input parameters to the conjugate gradient algorithm to avoid obtaining minimum points which have no physical meaning. In our case each spectral compoent used for deconvolution has been assumed to have a Gaussian analytical definition fully identified by three parameters (amplitude, central frequency, spectral bandwidth), so that the input values required to start the deconvolution process are the number M of Gaussian components and 3M suitable initial approximations of the parameters above. It is shown that all this information can be obtained from the measured data. The deconvolution procedure was implemented by a FORTRAN Microsoft Version 5.1 program and experimental results relative to spectroscopic data obtained by FT-IR analysis of human serum albumin are reported. The results are discussed and compared with data obtained by the use of other techniques.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080606
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  • 127
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    Digitale Medien
    Experimental design: A chemometric approach, 2nd edn, Stanley N. Deming and Stephen L. Morgan, Elsevier, Amsterdam, 1993, ISBN 0-444-891 11-0, 453 pp. $177.25, Dfl 310.00 (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 446-448 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080610
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  • 128
    Digitale Medien
    Digitale Medien
    Announcement (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. i 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180080611
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  • 129
    Digitale Medien
    Digitale Medien
    A correlation principal component regression analysis of NIR data (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 21-29 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Near-infrared absorbance ; Partial least squares ; Principal component regression ; Root-mean-square error of prediction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The use of principal component regression (PCR) as a multivariate calibration method has been discussed by a number of authors. In most situations principal components are included in the regression model in sequence based on the variances of the components, and the principal components with small variances are rarely used in regression. As pointed out by some authors, a low variance for a component does not necessarily imply that the corresponding component is unimportant, especially when prediction is of primary interest. In this paper we investigate a different version of PCR, correlation principal component regression (CPCR). In CPCR the importance of principal components in terms of predicting the response variable is used as a basis for the inclusion of principal components in the regression model. Two typical examples arising from calibrating near-infrared (NIR) instruments are discussed for the comparison of the two different versions of PCR along with partial least squares (PLS), a commonly used regression approach in NIR analysis. In both examples the three methods show similar optimal prediction ability, but CPCR performs better than standard PCR and PLS in terms of the number of components needed to achieve the optimal prediction ability. Similar results are also seen in other NIR examples.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090104
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  • 130
    Digitale Medien
    Digitale Medien
    Announcement (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. i 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090108
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  • 131
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    Digitale Medien
    International chemometrics research meeting (ICRM) (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 137-138 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090205
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  • 132
    Digitale Medien
    Digitale Medien
    Simple encoding of infrared spectra for pattern recognition. 1: Statistical examination of the effectiveness and information content by factor analysis (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 143-168 
    Details
    ISSN: 0886-9383
    Schlagwort(e): pattern recognition ; infrared spectra ; factor analysis ; maximum likelihood method ; entropy of information ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The spectral region from 700 to 3600 cm-1 is subdivided into several wave number intervals. The peaks in each interval are summarized by means of three encoding algorithms. Using a factor model of kcommon factors, the total extractable variacnce (com) of a given set of intervals is calculated and correlated with the redundancy of information in all these intervals. The value of com is verified by analysis of the factor loadings aik (factor pattern). Finally, the information content of some chosen sets of intervals coded by the three selected feature algorithms will be correlated to the probability of information flow through a serial-parallel network. The encoding using only wave numbers was found to be the most effective.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090303
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  • 133
    Digitale Medien
    Digitale Medien
    Diagnostics statistics in QSAR (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 211-221 
    Details
    ISSN: 0886-9383
    Schlagwort(e): diagnostics statistics ; QSAR ; MASCA ; principal component regression ; non-least squares regression ; types of multicollincarity ; flagged observations ; influential points ; high-leverage points ; outliers ; extra-carrier points ; random perturbation ; cluster correalation ; resampling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The formal application of a Hansch analysis to a series of 3-quinuclidinyl benzylates (QNBs) led to a ‘statistically significant’ QSAR equation. In contrast, the application of the MASCA model has shown that the design matrix is unsuitable for each QSAR analysis: one sample member is an outlier but not a high-leverage or influential point; another one is an influential point, a high-leverage point and an extra-carrier point. The regressors of the design matrix are multicollinear without predictive model power. The result of such flagged observation and this type of multicollinearity is a multiple cluster correlation. The QNB series is a good example for ‘sampling artifacts’ where no practically important but artificial QSARs can be found.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090307
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  • 134
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    Digitale Medien
    Stone and jonathan versus mager debate (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 230-231 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090311
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  • 135
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    Digitale Medien
    A review of robust process design approaches (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 239-262 
    Details
    ISSN: 0886-9383
    Schlagwort(e): industrial experimentation ; parameter design ; quality by design ; robust design ; Taguchi method ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The aim of this paper is to present a simple structured review of the different approaches to robust process design to clarify their similarities and dissimilarities. It is primarily written for practitioners who wish to understand and compare the main ideas of each approach and to apply them to their work. Two examples are used to illustrate the different approaches and their corresponding data analysis strategies: the first one is a constructed example on a pigment kneading process and the second one is real example dealing with the validation of an HPLC method. A comparison of the different approaches is provided and some practical recommendations are formulated.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090402
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  • 136
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    Digitale Medien
    PLS shrinks (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 323-326 
    Details
    ISSN: 0886-9383
    Schlagwort(e): partial least squares ; biased regression ; ordinary least squares ; minimum length least squares ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An algebraic proof is given that in partial least squares (PLS) regression the Euclidean length of the estimator is shrunk in comparison with the ordinary least squares estimator or with PLS estimators based on a larger number of dimensions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090406
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  • 137
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    Digitale Medien
    Masthead (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995) 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090501
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  • 138
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    Digitale Medien
    A simple iteration algorithm for PLS regression (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 363-372 
    Details
    ISSN: 0886-9383
    Schlagwort(e): PLS regression ; orthogonal expansion ; optimization ; Lagrange multipliers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple iteration algorithm that is faster and less memory-intensive than the NIPALS iteration algorithm for PLS regression is presented. The iteration algorithm is obtained by treating the orthogonal expansion or decomposition of a matrix X as an extremum problem subject to normalization and orthogonality constraint conditions and then solving the problem by use of the method of Lagrange multipliers. The main idea in this method is to find the transformation vector r. The latent variable t is expressed exactly as the linear combination of X-variables with the vector r so that the final regression coefficients can be conveniently provided. In the algorithm the recursion of the orthogonal projection is needed, which is derived by use of a matrix inverse formula. Algorithms are established from the equation for calculating the vector r that are suitable for dealing with three cases of large data sets. The first case is when the number of objects is very large, the number of variables is relatively small and the number of Y-variables is equal to or greater than the number of X-variables. The second case is when the number of objects is very large, the number of variables is relatively small and the number of X-variables is greater than the number of Y-variables. The last case is when the number of variables, either X- or Y-variables, or both, is very large and the number of objects is small.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090504
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  • 139
    Digitale Medien
    Digitale Medien
    Algorithm for finding an interpretable simple neural network solution using PLS (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 423-430 
    Details
    ISSN: 0886-9383
    Schlagwort(e): PLS ; neural network ; training ; interpretable ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This communication describes the combination of a feedforward neural network (NN) with one hidden neuron and partial least squares (PLS) regression. Through training of the neural network with an algorithm that is a combination of a modified simplex, PLS and certain numerical restrictions, one gains an NN solution that has several feasible properties: (i) as in PLS the solution is qualitatively interpretable; (ii) it works faster than or comparably with ordinary training algorithms for neural networks; (iii) it contains the linear solution as a limiting case. Another very important aspect of this training algorithm is the fact that outlier detection as in ordinary PLS is possible through loadings, scores and residuals. The algorithm is used on a simple non-linear problem concerning fluorescence spectra of white sugar solutions.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090508
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  • 140
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    Digitale Medien
    Conference announcement (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 439-439 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090512
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  • 141
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    Digitale Medien
    A PLS kernel algorithm for data sets with many variables and few objects. Part II: Cross-validation, missing data and examples (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 459-470 
    Details
    ISSN: 0886-9383
    Schlagwort(e): PLS ; kernel algorithm ; multivariate calibration ; EM algorithm ; cross-validation ; missing data ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This is Part II of a series concerning the PLS kernel algorithm for data sets with many variables and few objects. Here the issues of cross-validation and missing data are investigated. Both partial and full crossvalidation are evaluated in terms of predictive residuals and speed and are illustrated on real examples. Two related approaches to the solution of the missing data problem are presented. One is a full EM algorithm and the second a reduced EM algorithm which applies when the number of missing values is small. The two examples are multivariate calibration data sets. The first set consists of UV-visible data measured on mixtures of four metal ions. The second example consists of FT-IR measurements on mixtures consisting of four different organic substances.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090604
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  • 142
    Digitale Medien
    Digitale Medien
    Orthogonal canonical variates for discrimination and classification (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 509-520 
    Details
    ISSN: 0886-9383
    Schlagwort(e): canonical variates ; discriminant analysis ; partial least squares ; principal components ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new set of derived variables is proposed for exhibiting group separation in multivariate data on for preprocessing such data prior to discriminant analysis. The technique combines optimal features of canonical variate analysis and principal component analysis: the derived variables are linear combinations of the original variables that optimize the canonical variate criterion (ratio of between-group to within-group variance) but subject to the orthogonality constraints of principal components. In this formulation the canonical variates can be derived even when the within-group matrix is singular (i.e. when there are more variables than objects in the data matrix). A simple computational algorithm for extraction of these variables is proposed. The methods are illustrated on several data sets and compared with alternative techniques such as principal component analysis and partial least squares.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090608
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  • 143
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    Digitale Medien
    The Unscrambler®, Version 5.5. Multivariate analysis software for MS-DOS. Available from CAMO A/S, Olav Tryggvasons Gate 24, N-7011 Trondheim, Norway (Telephone: (+47) 7351 4966, Fax: (+47) 7351 4257) or from CAMO USA, 435 Blake Street, Menlo Park, CA 94025, U.S.A. (Telephone/Fax: (+1 415) 324-4286, Internet: teledyn@netcom.com). Single-copy price NOK 26 900 commercial, NOK 18 800 non-commercial, NOK 11 900 academic (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 527-529 
    Details
    ISSN: 0886-9383
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cem.1180090612
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  • 144
    Digitale Medien
    Digitale Medien
    Gas chromatography mass spectrometry of some thermally labile urea pesticides (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 39-42 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The application of gas chromatography/mass spectrometry to three thermally labile phenylurea pesticides is reported. Using alcohols as solvents the decomposition of the pesticides is followed by a reaction in which esters of N-(3,4-dichlorophenyl)carbamic acid are formed. As these reactions occur during the gas chromatographic analysis, it is the esters which are identified in the mass spectrometer. The methyl ester is itself a pesticide so an erroneous conclusion about the original pesticide could be reached when methanol is the solvent.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140109
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  • 145
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    Digitale Medien
    252Cf plasma desorption fourier transform ion cyclotron resonance mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 43-45 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ions produced by 252Cf plasma desorption are detected by Fourier transform ion cyclotron resonance techniques. Results for CsI and N,N,N-trimethyl-p-aminophenolate iodide show the feasibility of the technique with high resolution (up to 11 000 at m/z 23) and good signal-to-noise ratio (up to 726).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140110
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  • 146
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    Digitale Medien
    Camera-ready BEMS short communications - guidelines for authors (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 47-48 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140111
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  • 147
    Digitale Medien
    Digitale Medien
    BEMS short communication (camera-ready example) (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 49-50 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140112
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  • 148
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    Digitale Medien
    Forthcoming events (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 51-51 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140113
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  • 149
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    Digitale Medien
    Fast atom bombardment mass spectrometry of butyloxycarbonyl protected (BOC) peptides (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 53-61 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The fast atom bombardment positive ion mass spectra and the [M + H]+ collisional activation spectra of t-butyloxycarbonyl protected peptides and the unprotected analogues have been compared. It is concluded that sequence information, especially from the collisional activation spectra, can better be derived from the underivatized peptides than from the BOC-peptides.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140202
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  • 150
    Digitale Medien
    Digitale Medien
    Profiling and quantification of biogenic amines in wine by constant B2E linked scan mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 229-233 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The constant B2E linked scan is shown to be an excellent tool for the profiling of biogenic amines in wine samples. The fragment ion at m/z 169 of the dansylated amines is used for the precursor ion search in combination with direct sample evaporation. Besides the profile a semi-quantification may be achieved when using suitable amines as internal standards with standard deviations of 12-17%. More accurate results with standard deviations of 3-5% are obtained when using deuterated analogues as internal standards. Both methods are applied to the analysis of biogenic amines in synthetic mixtures and actual wine samples.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140506
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  • 151
    Digitale Medien
    Digitale Medien
    252-Californium plasma desorption mass spectrometry of glycerophospholipids (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 241-246 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 252-Californium plasma desorption mass spectrometry was applied to the study of five different classes of phospholipids namely phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine and phosphatidylinositol. Positive and negative ion spectra were compared to spectra obtained using other ionization techniques. Plasma desorption mass spectra provide useful information on the molecular weight of compounds from all classes, particularly in the case of phosphatidylserine - a class that has failed to show satisfactory quasimolecular ions with either Fast atom bombardment, FAB or Field desorption, FD. The observed fragmentation is also indicative of the structure of the studied compounds.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140508
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  • 152
    Digitale Medien
    Digitale Medien
    Quantitative analysis of S3341 in human plasma and urine by combined gas chromatography - negative ion chemical ionization mass spectrometry: 15 month inter-day precision and accuracy validation (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 289-293 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new quantitative assay for the determination of S3341, an alpha-2 agonist antihypertensive drug, has been developed using combined gas chromatography-negative ion chemical ionization mass spectrometry. The [M]-. ions from TFA derivatives of S3341 (m/z 276) and the internal standard (2H4)S3341 (m/z 280) are monitored simultaneously by selected ion monitoring. For S3341 concentrations ranging from the limit of detection (0.2 ng ml-1 using 1 ml of plasma) to 5 ng ml-1, the average assay precision (CV) is approximately 7% while the average assay accuracy (percentage of error) is 4%. Validation of the day-to-day precision and accuracy was realized after analysing control plasma samples (n = 295) concurrently with the biological samples collected during the pharmacokinetic studies conducted over 15 months. The average day-to-day precision (CV) and accuracy (percentage of error) are 10% and 6% respectively, thus indicating that this assay procedure routinely provides reliable analytical data.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140608
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  • 153
    Digitale Medien
    Digitale Medien
    Improvement in sensitivity of fast atom bombardment mass spectrometry of amino acids by di-isopropylphosphorylation (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 331-333 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Positive ion fast atom bombardment mass spectrometric sensitivities of seven amino acids and the corresponding di-isopropylphosphorylated derivatives were carefully compared. Results showed that an improvement in sensitivity by factors of 4-29, mostly above 10, were achieved after the derivatization. The chemical noise derived from glycerol matrix was also greatly reduced by this derivatization.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140706
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  • 154
    Digitale Medien
    Digitale Medien
    Analysis of cholesterol, cholesterol-5,6-epoxides and cholestane-3β,5α,6β-triol in nipple aspirates of human breast fluid by gas chromatography/mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 335-338 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method has been developed for the quantitative determination of cholesterol and three of its major oxidative metabolites (the 5α,6α-epoxide, the 3β,5α,6β-triol, and the 5β,6β-epoxide) in a single sample of human breast fluid (2-50 μl), using gas chromatography/mass spectrometry with selected ion monitoring. High specificity and reliable quantification is achieved by the use of the inverse stable isotope dilution method, employing deuterium-labeled variants of the compounds as internal standards.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140707
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  • 155
    Digitale Medien
    Digitale Medien
    Simultaneous determination of pool sizes and fractional turnover rates, of deoxycholic acid, cholic acid and chenodeoxycholic acid in man by isotope dilution with 2H and 13C labels and serum sampling (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 609-611 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper describes a method for simultaneous determination of the kinetics of the three major bile acids in man using (2,2,4,4-2H4) deoxycholic acid, (24-13C) cholic acid and (24-13C) chenodeoxycholic acid. The gas chromatographic/mass spectrometric-selected ion monitoring technique used provided complete separation of deoxycholic acid, cholic acid and chenodeoxycholic acid, which permitted simultaneous measurement of isotope ratios for all three bile acids. Since measurement of all three pool sizes and fractional turnover rates in a single experiment requires different isotopic labels for deoxycholic acid and cholic acid, we investigated the in vivo stability and applicability of (2,2,4,4-2H4) deoxycholic acid as a stable isotope marker for isotope dilution studies in man. No consistent differences were observed between deoxycholic acid pool sizes and fractional turnover rates determined in serum samples after administration of (2,2,4,4-2H4) deoxycholic acid and (24-13C) deoxycholic acid. Simultaneous administration of (2,2,4,4-2H4) deoxycholic acid (24-13C) cholic acid and (24-13C) chenodeoxycholic acid and isotope ratio measurements in serum permitted determination of pool sizes and fractional turnover rates of the three major bile acid and the 7α-dehydroxylation fraction. Pool sizes, fractional turnover rates and synthesis rates (input rates) agreed well with data obtained previously with (24-13C) labels in independent studies.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200141106
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  • 156
    Digitale Medien
    Digitale Medien
    Identification of new steroids in patients with 17α-hydroxylase deficiency by capillary gas chromatography/mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 633-637 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Urines of two children with 17α-hydroxylase deficiency contained a number of 5-pregnane- and pregnenediols, -triols and -tetrols with a hydroxy or oxo group in position 11 of the steroid ring. They are formed mainly from progesterone via 11-hydroxyprogesterone, pregnanolone and corticosterone, respectively, or from pregnenolone. Three metabolites not previously described, 16-hydroxypregnenolone, 6,21-dihydroxypregnanediol and 6-hydroxytetrahydrocorticosterone, were identified.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200141111
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  • 157
    Digitale Medien
    Digitale Medien
    Gas chromatographic/mass spectrometric studies of the urinary metabolites of male rats given indan (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 649-651 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The identified urinary metabolites of male rats exposed to indan are: 1- and 2-indanone; 1-, 2- and 5-indanol; 2-and 3-hydroxyl-1-indanone; and cis- and trans-indan-1,2-diol. Indan causes kidney damage in male rats in a manner similar to the cyclic hydrocarbons cis- and trans-decalin and JP-10. Lesions produced by indan occur only in male rats and not in female or control rats.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200141114
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  • 158
    Digitale Medien
    Digitale Medien
    Routine gas chromatographic/mass spectrometric analysis of urinary organic acids. Results over a three-year period (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 663-668 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organic acidaemias are an important part of inborn errors of metabolism. The biochemical diagnosis is based on gas chromatographic/mass spectrometric identification of urinary organic acids. Since 1973 we have used gas chromatographic analysis of the methyl esters of urinary organic acids. Mass spectral identification was performed only when an abnormal gas chromatographic profile was suspected. In 1983 we introduced routine gas chromatographic/mass spectrometric analysis organic acids. More than 1500 urine samples from 1000 children have been analysed and we encountered more than 40 abnormal profiles: 18 classical organic acidaemias (propionic, methyl-malonic, isovaleric, glutaric type I and 3-hydroxy-3-methyl glutaric acidaemias); 6 aminoacidopathies with excretion of branched chain keto acids (leucinosis) or succinylacetone (tyrosinosis type I); 14 massive dicarboxylic acidurias with excretion of suberyl and hexanoyl glycine and deficiency of the medium chain acyl CoA dehydrogenase in four patients. The use of gas chromatography/mass spectrometry routinely allows the identification of abnormal metabolites excreted in small amounts: β-methyl-crotonyl glycine indicative of biotin deficiency: γ-hydroxybutyric acid; and 3-methyl-glutaconic + 3-methy-glutaric acid is in a 3-methyl-glutaconic aciduria type II. Abnormal profiles due to metabolites of drugs as valproate, salicylate and barbiturate can be recognized immediately. This simple gas chromatographic/mass spectrometric system can lead to diagnosis, in one day, of rare but severe diseases needing a specific and early treatment.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200141117
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  • 159
    Digitale Medien
    Digitale Medien
    Determination of serum cortisol by thermospray liquid chromatography/mass spectrometry: Comparison with gas chromatography/mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 717-722 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The determination of serum cortisol by thermospray liquid chromatography/mass spectrometry (LC/MS) has been assessed. The method incorporates stable isotope dilution and innumoadsorption extraction. [M + H]+ ions are monitored during LC/MS. The within-assay reproducibility is satisfactory (coefficient of variation 7% at a concentration of 190 ng ml-1), though inferior to that achieved with the (more lengthy) procedure of gas chromatography/mass spectrometry (GC/MS). Satisfactory agreement between LC/MS (y) and GC/MS (x) data was observed (y = 0.934x + 12.4 ng ml-1; r = 0.968; n = 14). It is concluded that the generation of precise reference data for the assessment of routine cortisol assays is at present better achieved by GC/MS. LC/MS, however, provides satisfactory quantitative data via a more simple and rapid method.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200141205
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  • 160
    Digitale Medien
    Digitale Medien
    The alkylthio-isoindole derivatives of biogenic amines: A mass spectrometric study (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 737-738 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200141208
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  • 161
    Digitale Medien
    Digitale Medien
    Rapid quantification of 11 prostanoids by combined capillary column gas chromatography and negative ion chemical ionization mass spectrometry: Application to prostanoids released from normal human embryonic lung fibroblasts WI38 in a culture medium (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 25-32 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rapid and simultaneous quantification of 11 prostanoids has been carried out with a short-capillary gas chromatograph and negative ion chemical ionization (ammonia) mass spectrometer.The methoxime-trimethylsilyl ether-pentafluorobenzyl esters (MO-TMS-PFB) of nine prostanoids, PGA1, PGA2, PGB1, PGB2, PGD2, PGE1, PGE2, 6-oxo-PGF1α and TXB2 and the TMS-PFB of two prostanoids, PGF1α and PGF2α, were separated in less than 5.5 min on a bonded OV-1 capillary column 0.25 mm i.d. × 6 m (0.15 μm thickness) using hydrogen as a carrier gas. PGD2, PGE2, PGF2α, 6-oxo-PGF1α and TXB2 were quantified up to 2.5 fmol injected (0.1 pmol derivatized) and both PGA2 and PGB2 up to 25 fmol injected (1 pmol derivatized).In order to maintain the stability of the prostanoids containing a carbonyl group, such as TXB2 during the purification and derivatization steps of biological materials, methyl acetate was used in place of methyl formate as an eluant for Sep-Pak C18 purification.Normal human embryonic lung fibroblasts W138 (5.63 × 105 cells in a log phase) produced: PGA2 15.28, PGB2 13.48, PGD2 7.95, PGE1 2.62, PGE2 177.76, PGF2α 25.14, 6-oxo-PGF1α 27.33 and TXB2 61.00 pmol in 10 ml of Eagle minimal essential medium.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150105
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  • 162
    Digitale Medien
    Digitale Medien
    Measurement of urinary lactic, 3-hydroxybutyric, pyruvic and acetoacetic acids in a single analysis using selected ion monitoring and stable isotope labelling techniques (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 57-62 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Sodium borodeuteride treatment of urine expected to have large concentrations of pyruvic and acetoacetic acids produces lactic and 3-hydroxybutyric acids labelled with deuterium. Mass fragmentographic techniques applied to the trimethylsilyated extract of the urine spiked with more extensively labelled analogues as internal standards permit the reliable determination of lactic, pyruvic, 3-hydroxybutyric and acetoacetic acids in a single analysis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150108
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  • 163
    Digitale Medien
    Digitale Medien
    Characterization of trichothecenes by ammonia chemical ionization and tandem mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 79-87 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ammonia and deuterated ammonia chemical ionization (CI) mass spectra and collisionally activated dissociation (CAD) mass spectra of ammonium adduct ions are presented for ten trichothecenes. The samples were introduced by direct exposure probe. Effects of ion source temperature and pressure on the ammonia CI gas plasma and the formation of the ammonium adduct ion were studied. The CI conditions were optimized to produce a maximal yield for the ammonium adduct ion of trichothecenes, i.e. the parent ion for tandem mass spectral analysis. Besides source temperature and pressure, proton affinity and the stability of the ammonium adduct ion affect the relative abundance ratio of [M + H]+:[M + NH4]+ in ammonia CI and CAD mass spectra. The ratio [M + H]+:[M + NH4]+, and hence the stability of the ammonium adduct ion, are largely determined by the functional groups (hydroxy, carbonyl, acetoxy, and isovaleroyloxy) and their location in the trichothecene nucleus. The most abundant fragment ions in the ammonia CI spectra and the most abundant daughter ions in the CAD spectra of the ammonium adduct ions are formed by the losses of ammonia and functional groups as neutrals in various combinations.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150205
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  • 164
    Digitale Medien
    Digitale Medien
    The application of gas chromatographic/mass spectrometric techniques to spin trapping. Conversion of α-phenyl N-tert-butyl nitrone (PBN) spin adducts to stable trimethylsilylated derivatives (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 111-116 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of an aminoxyl and the corresponding hydroxylamine with silylating agents is studied in detail. The gas chromatographic/mass spectrometric analysis of the products is consistent with the production of an unsaturated product when an alkyl group with exchangeable hydrogens is attached to the nitrone group. The structure of this compound is confirmed by deuteration. It is concluded that aminoxyls themselves do not derivatize wth silylating agents.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150209
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  • 165
    Digitale Medien
    Digitale Medien
    Gas chromatography/mass spectrometry and gas chromatography/tandem mass spectrometry of methyl ester/methoxime/trimethylsilyl ether derivatives of prostaglandins (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 129-138 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electron impact mass spectra of methyl ester/trimethylsilyl ether derivatives of prostaglandin F2α and methyl ester/methoxime/trimethylsilyl ether derivatives of prostaglandin E2, prostaglandin D2, 6-oxo-prostaglandin F1α and 2,3-dinor-6-oxo-prostaglandin F1α are presented. Most of the prostaglandins studied have additionally been 2H-labelled at different sites in order to assign the corresponding fragment ions. Collisionally activated decomposition mass spectra of the most intense parent ions in the high-mass region were taken. High-intensity, prostaglandin-characteristic daughter fragments will allow a reliable quantification of prostaglandins in biological fluids and a reduction of sample clean-up.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150303
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  • 166
    Digitale Medien
    Digitale Medien
    A gas chromatographic/mass spectrometric assay for catechol estrogens in microsomal incubations: Comparison with a radiometric assay (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 157-161 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A gas chromatographic/mass spectrometric assay for quantifying two catechol estrogens, 2-hydroxyestradiol and 4-hydroxyestradiol, in microsomal preparations is described. The assay employs deuterium-labeled analogs of the catechol estrogens as internal standards and permits quantification of catechol estrogens, in microsomal incubations, at low (1-2) μM concentrations. The compounds are analyzed as their trimethylsilyl derivatives following separation by capillary gas chromatography.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150307
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  • 167
    Digitale Medien
    Digitale Medien
    Electron capture negative ion chemical ionization analysis of arachidonic acid (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 175-178 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A highly sensitive (subpicomole level) and structural specific method for the analysis of arachidonic acid esterified to complex glycerophospholipids has been developed using combined capillary gas chromatography and mass spectrometry. The methodology is based upon the formation of the pentafluorobenzyl ester of arachidonic acid, which is efficiently ionized using electron capture negative ion chemical ionization conditions to yield an abundant carboxylate anion at m/z 301. Quantification is carried out following hydrolysis of the complex glycerophospholipid in the presence of a known amount of (2H8) araachidonic acid. The use of this method is illustrated by the quantification of arachidonic acid within the glycerophospholipid classes isolated from resident peritoneal macrophage cells isolated from HS mice.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150309
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  • 168
    Digitale Medien
    Digitale Medien
    Mass spectral investigations on trichothecene mycotoxins. V. Direct analysis of satratoxins by tandem mass spectrometric techniques (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 185-191 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Under chemical ionization conditions, satratoxins preferentially produce negatively charged molecular ions (M-·) over the positively charged protonated molecules. Collisionally activated dissociation of the M-· ions resulted in daughter ions and neutral losses which were characteristic of the macrocyclic ester bridges. Direct tandem mass spectrometric methods of analyses wee developed and applied for the detection and quantification of satratoxins in Stachybotrys atra fermentation broths. Minimum detectable levels for satratoxin standards were 5 pg. A synthetically modified macrocyclic trichothecene, 8-ketoverrucarin A, was used as an internal standard for the quantification of satratoxins in fermentation samples.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150402
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  • 169
    Digitale Medien
    Digitale Medien
    Thermospray liquid chromatography tandem mass spectrometry: Application to the elucidation of zolpidem metabolismThis work was presented in part at the 4th Symposium on Liquid Chromatography/Mass Spectrometry and Mass Spectrometry/Mass Spectrometry, Montreux (Switzerland), October 22-24, 1986. (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 223-228 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper discusses the possible advantages of thermospray liquid chromatography/tandem mass spectrometry LC/MS/MS for metabolic mapping. The technique was applied to the study of the metabolism of zolpidem, a new hypnotic with an imidazo-pyridine moiety. When compared to other chromatographic/mass spectrometric-based techniques, reversed phase high-performance liquid chromatography coupled with thermospray LC/MS/MS appears to be the fastest method available today for elucidation of unknown metabolic structures, since it allows identification by direct injection of concentrated urine. However, it was noted during the thermospray process that loss of formaldehyde from a hydroxymethyl amide metabolite occurred. This degradation was not observed when this metabolite was analysed by gas chromatography/mass spectrometry following trimethylsilylation.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150406
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  • 170
    Digitale Medien
    Digitale Medien
    Fast atom bombardment mass spectrometry of high-molecular-weight fraction of porphyrin-based photodynamic therapy drugs (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 257-263 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photodynamic therapy (PDT) involves the treatment of tumor tissue with a photosensitizer and light to effect the delineation and/or eradication of the tumor. PDT is a two step process: (1) incorporation of photosensitizer into the cell where it must be retained by tumors in vivo; and (2) illumination of the tumor cell with light to effect cell death. Hematoporphyrin derivative (HPD) is a complex mixture of porphyrins currently used for PDT in the clinical setting. Hematoporphyrin-based oligomers of up to five subunits were determined using fast atom bombardment mass spectrometry of the high-molecular-weight fraction of the drug. Reduction of this fraction with LiAlH4 permitted determination of the covalent bond linking the monomers in these oligoporphyrins. Application of these analytical procedures to the determination of the composition of different preparations of HPD will be described.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150505
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  • 171
    Digitale Medien
    Digitale Medien
    (18O)quinolinic acid: Its esterification without back exchange for use as internal standard in the quantification of brain and CSF quinolinic acid (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 291-293 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the process of developing a high-sensitivity negative chemical ionization gas chromatographic/mass spectrometric assay for brain and cerebrospinal fluid (CSF) levels of quinolinic acid (QUIN, 2,3-pyridine dicarboxylic acid), (18O4)QUIN was prepared. Its properties as an internal standard were compared with those of the structural isomer 2,4-pyridine decarboxylic acid (2,4-PDC) previously used by others. All oxygen atoms in QUIN were labeled by heating in 3N HCl/(18O)water for 48 h at 80°C. Back-exchange of (18O4)QUIN was prevented during derivatization to an electron-capturing dihexafluoropropanol ester by using trifluoroacetylimidazole as catalyst instead of perfluroacyl anhydrides. When mixtures of QUIN and (18O4)QUIN and/or 2,4-PDC were followed through a procedure to isolate and quantify brain and CSF QUIN, the variability in the ratio of QUIN:2,4-PDC was greater than for QUIN:(18O)QUIN. We conclude that (18O)QUIN is the preferred internal standard in gas chromatographic/mass spectrometric quantification of brain and CSF QUIN, and that (18O)-labeled carboxylic acids may be esterified effectively without back-exchange using acylimidazole reagents.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150509
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  • 172
    Digitale Medien
    Digitale Medien
    252CF plasma desorption mass spectrometry of a polycyclic peptide antibiotic, Nisin (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 305-310 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polycyclic peptide antibiotic, Nisin, has been analysed by plasma desorption mass spectrometry using two different sample preparation techniques and two versions of the commercial plasma desorption mass spectrometer, and a prototype with high resolving power. The spectra obtained allow identification of a major component and two minor analogues. Extensive fragmentation is observed in samples prepared by the electrospray technique, whereas only ions indicating the molecular weight are produced when the sample is adsorbed on nitrocellulose.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150602
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  • 173
    Digitale Medien
    Digitale Medien
    Measurement of mevalonate in human plasma and urine by multiple selected ion monitoring (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 174-176 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Plasma levels and urinary excretion of mevalonate were reported to be correlated with cholesterol biosynthesis. Evaluation of mevalonate concentration in plasma and urine represents therefore a non-invasive method for studying the modifications of cholesterol synthesis. A method is described here by wich mevalonate in plasma and urine is determined by the selected ion monitoring technique after extraction as mevalonolactone and conversion into the trimethylsilyl ether. Linear responses were obtained in the evaluation of mevalonate added to plasma in the 10-100 ng/ml (r 〉 0.995) and to urine in the 50-1000 ng/ml concentration ranges, respectively. Identity of mevalonate in plasma and urine was confirmed by high-resolution mass spectrometry.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180305
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  • 174
    Digitale Medien
    Digitale Medien
    Fast atom bombardment of metal-pyochelin complexes: Metastable analysis at constant B/E of zinc-pyochelinMention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable. (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 185-191 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Fast atom bombardment (FAB) mass spectrometry was used to characterize the pyochelin complexes of iron and zinc. Ferripyochelin readily forms the [M + H]+ and [2M + H]+ ions in a glycerol matrix. The molecular ion was 2.5 fold more abundant when acetic acid was present. Iron was shown to be present in the iron-pyochelin complex as the ferric ion by wet chemical methods. Differentiation between ferric and ferrous ions by FAB was not successful owing to the FAB reducing environment. Ferric ions were reduced by FAB to ferrous ions in the following model salts - ferric chloride, ferric nitrate and ferric sulfate - when dissolved in either glycerol, thioglycerol or the magic bullet matrix. Ferric and ferrous chloride salts gave virtually identical spectra with a glycerol/acetic acid matrix. Zinc-pyochelin readily forms the [M + H]+ and [2M + H]+ ions, but only when acetic acid was present in the glycerol matrix. The FAB mass spectrum of zinc-pyochelin exhibited various fragmentations which can be used in structural analysis. Linked-scan at constant B/E and accurate mass data were used to characterize the fragmentations of the zinc-pyochelin complex. Metastable analysis allowed the fragmentation pathway of zinc-pyochelin to be determined.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180307
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  • 175
    Digitale Medien
    Digitale Medien
    Electron impact mass spectrometry of BHT and its alteration products (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 207-217 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electron impact (EI) mass spectra of 2,6-di-tert-butyl-4-methylphenol (BHT) and certain of its alteration products are described in detail. Accurate mass measurements confirm the elemental compositions of important fragment ions in the EI spectra. Collisionally activated mass spectra are also used to study fragmentation and suggest common ion structures. The reference spectra provide the basis for identifying various alteration products of BHT by capillary gas chromatography/mass spectrometry (GC/MS) without the necessity of isolating individual components. Application of GC/MS is made to three studies: (i) pyrolysis of hydroperoxy-BHT as a potential pathway to alteration products in food; (ii) GC/MS pyrolysis of hydroperoxy-BHT as a model study; and (iii) alteration of BHT in ethanol/water as a food-simulating solvent.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180310
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  • 176
    Digitale Medien
    Digitale Medien
    Fast atom bombardment mass spectrometry of the D-aldohexoses and some deoxyaldohexoses (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 363-372 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The MI and CA spectra of selected positive and negative ions generated by fast atom bombardment (FAB) of the stereoisomeric aldohexoses can be used to differentiate among these isomers, without prior derivatization or addition of other substances. The main fragmentation routes were traced and compared to those of some 2- and 6-deoxyaldohexoses, which appeared to be suitable model compounds. In both positive and negative ion FAB mass spectrometry, the OH group at the C-2 position plays an important role in the fragmentation reactions of the pseudomolecular [M + glycerol + H]+ and [M - H]- ions.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180603
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  • 177
    Digitale Medien
    Digitale Medien
    Rapid identification of calbindin-D28k cyanogen bromide peptide fragments by plasma desorption mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 387-393 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Chicken intestinal calbindin-D28k is an intracellular protein which is believed to have a fundamental role in vitamin D-mediated transport of calcium. A mapping approach based on 252Cf plasma desorption mass spectrometry (PD mapping) was used to screen the DNA-deduced sequence of calbindin-D28k for sequence changes and posttranslational modifications. In the PD mapping experiment, purified calbindin-D28k was cleaved with cyanogen bromide and the resulting peptides were subjected to PD mass spectrometric analysis either as a mixture or as high-performance liquid chromatography isolated fractions. The DNA-derived primary structure of calbindin-D28k was confirmed by rapid PD mass spectral identification of the CNBr peptide fragments, and the nature of the N-terminal blocking group was readily determined to be an acetyl group. The relatively non-destructive nature of the PD mass spectrometric analysis allowed the mapping of the N-terminal peptide through an additional in situ V8 protease enzymatic reaction.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180605
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  • 178
    Digitale Medien
    Digitale Medien
    Rapid determination of sequence variations in actinidin isolated from Actinidia chinensis (var. Hayward) using fast atom bombardment mapping mass spectrometry and gas phase microsequencing (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 424-428 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A current limitation in the use of fast atom bombardment (FAB) mass spectrometric mapping of peptide mixtures, derived from enzymic digestion of proteins, is that most of the hydrophilic peptides are not observed. However, it has been demonstrated from previous work that esterification of the peptide mixture results in the detection of almost all peptides in FAB mass spectrometry. This strategy of FAB mapping was applied to the protein actinidin, isolated from an Italian variety of Actinidia chinensis. Two of the 12 tryptic peptides in FAB mass spectrometry did not exhibit molecular ions predicted from the known sequence of actinidin isolated from the New Zealand variety of A. chinensis. The two peptides were isolated by high-performance liquid chromatography, subjected to Staphylococcus aureus V8 protease digestion and sequenced by gas-phase microsequencing. Nine changes in amino acid composition were detected using the rapid and powerful combination of FAB mass spectrometric mapping and gas-phase microsequencing.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180611
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  • 179
    Digitale Medien
    Digitale Medien
    Studies on anabolic steroids II - gas chromatographic/mass spectrometric characterization of oxandrolone urinary metabolites in manFor Part I see Ref. 1. (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 429-438 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metabolism of 17α-methyl-17β-hydroxy-2-oxa-5α-androstan-3-one (oxandrolone) in man has been investigated by gas chromatography/mass spectrometry. After oral administration of a 10 mg dose to man, five metabolites were detected in the free fraction of the urinary samples. Oxandrolone, the major compound excreted in urine, was detected within 72 h after administration. During this period 35.8 and 8.4% of the administered dose was excreted as unchanged oxandrolone and 17-epioxandrolone, respectively. In addition, minute amounts of 16α- and 16β- hydroxyoxandrolone and a δ-hydroxy acid resulting from the hydrolysis of the lactone group of oxandrolone were detected in the urine samples 8-60 h after administration. Furthermore, the susceptibility of oxandrolone to hydrolysis was investigated under several pH conditions. Extraction and fractionation of steroidal metabolites was achieved by using C18 and silica Sep Pak™ chromatography. The mass spectra of the metabolites are presented and major fragmentation pathways discussed.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180612
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  • 180
    Digitale Medien
    Digitale Medien
    Gas chromatographic and gas chromatographic/tandem mass spectrometric characterization of precursors on the sesterterpene pathway for steroid biosynthesis (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 572-575 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An increasing amount of evidence is accumulating to support the proposal that steroidogenesis can occur by a sesterterpene pathway as well as the cholesterol pathway. Key intermediates on the sesterterpene pathway are 23,24-dinor-5-cholen-3β-ol (guneribol) and some of its metabolites, e.g. 23,24-dinor-4-cholen-3-one (guneribone). It has been reported that these intermediates are biosynthesized and converted to steroid hormones by a range of endocrine tissues in vitro. Monitoring the pentafluorobenzyloxime derivatives by negative ion chemical ionization mass spectrometry in the electron capture mode provided evidence for the presence of guneribone in extracts of bovine testicular and human adrenal tumour tissue. Complementary evidence was obtained from gas chromatographic/tandem mass spectrometric data generated on a triple-quadrupole instrument by monitoring daughter ions (in the multiple ion detection, MID mode) of the molecular anion of derivatized guneribone in both standards and tissue extracts. The present findings that sesterterpene pathway intermediates are present as endogenous compounds in tissue extracts, together with the previously reported radiochemical data, give further support to the sesterterpene pathway hypothesis.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180811
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  • 181
    Digitale Medien
    Digitale Medien
    Determination of cyclic butylboronate esters of some 1,2- and 2,3-diols in plasma by high-resolution gas chromatography/mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 592-597 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A gas chromatographic/mass spectrometric analytical procedure is described to determine glycols in plasma as cyclic butyl boronate esters. The method, involving a pre-deproteinization step, required only 0.25 ml of plasma and a short time (20 min) to react with the derivatizing agent (butyl boronic acid). The gas chromatographic separation on a CP Sil 8 CB silica capillary column coupled to a mass detector assured a complete identification of the compounds. The analytical recoveries (〉95%) with low coefficient of variation (4-11%) assured the feasibility of the method over a concentration range from 5 to 1000 μg ml-1 for each glycol. The lower detection limits, namely 1-5 μg ml-1, confirmed the sensitivity of the method.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180814
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  • 182
    Digitale Medien
    Digitale Medien
    Isotope labelling of lipids using the Favorsky rearrangement (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 603-612 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of tetradeuterated 10-methylundecanoic acid, dideuterated tetracos-2-enoic acid, (1-14C)pristanic acid and (1-14C)tetracos-2-enoic acid using the Favorsky rearrangement are described. They will be used for studies of long-chain fatty acid metabolism in patients. The positions of isotope labelling were determined by mass spectrometry.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180816
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  • 183
    Digitale Medien
    Digitale Medien
    Structure analysis of modified oligodeoxyribonucleotides by negative ion fast atom bombardment mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 617-619 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Negative ion fast atom bombardment mass spectrometry is used to verify the sequence of oligodeoxyribonucleotides containing a single modified nucleotide. Both the position in the sequence and the molecular weight of the modified nucleotide can be determined from the 3′ and 5′-phosphate sequence ions which are prominent in the mass spectrum.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180818
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  • 184
    Digitale Medien
    Digitale Medien
    A comparison of positive ion and negative ion fast atom bombardment mass spectral data for some sulphonyl hydrazones and derivatives (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 620-623 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A number of sulphonyl hydrazones and derivatives have been synthesized and tested for biological activity as pesticides during the crop protection research programme at the Hatfield Polytechnic. A recent comparative ionization study of some of these compounds using electron impact (EI), fast atom bombardment (FAB) and various chemical ionization methods showed FAB mass spectrometry to be the optimum technique to use in terms of molecular weight information obtained. This study compares the FAB mass spectral data in positive and negative ion mode using an alternating positive and negative ion detection system.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180819
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  • 185
    Digitale Medien
    Digitale Medien
    Rapid structural analysis of the in vitro and in vivo metabolism of SK&F 95448 by the combined use of thermospray liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 637-644 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermospray liquid chromatography/mass spectrometry (LC/MS) interface has had a major impact on the direct analysis of the metabolic fate of xenobiotics in complex biological media. This paper outlines the rapidity and power of the LC/MS approach, and shows how detailed structural information can be obtained without recourse to individual compound isolation. This provides a great saving in time and effort. The additional specificity of liquid chromatography/tandem mass spectrometry is highlighted in identifying the sites of metabolic transformation. The ability to handle biological samples with little or no clean-up using wide high-performance liquid chromatographic gradients is a key feature of the success of this methodology.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180822
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  • 186
    Digitale Medien
    Digitale Medien
    Phytochemical studies on the essential oils of species belonging to the Achillea genus by gas chromatography/mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 629-636 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several populations of Achillea species were collected from Hungarian localities. The characteristic composition cf the essential oils of almost 220 populations were determined by gas chromatography/mass spectrometry. The main component of Achillea asplenifolia, A. setacea and A. collina oils is chamazulene, with a molecular mass of 184. The composition of some A. setacea is different: instead of chamazulene it contains a significant amount of farnesene. Oils of A. distans, A. crithmifolia, A. nobilis, A. pannonica and A. ochroleuca contain some different and specific compounds instead of chamazulene. During the analysis of many essential oils, we found some very interesting differences within species originating from another geographical area.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180821
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  • 187
    Digitale Medien
    Digitale Medien
    Gas chromatography/mass spectrometry and gas chromatography/mass spectrometry/mass spectrometry of methyl ester/methoxime/trimethylsilyl ether derivatives of thromboxanes (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 139-142 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electron impact mass spectra of methyl ester/methoxime/trimethylsilyl ether derivatives of thromboxane B2 (TxB2) and 2,3-dinor-TxB2 and methyl ester/trimethylsilyl ether derivative of 11-dehydro-TxB2 are presented. Additionally, the derivatives of (2H4)-thromboxanes and methyl ester (2H3)-methoxime/trimethylsilyl ether derivatives of TxB2 and 2,3-dinor-TxB2 and (2H3)-methyl ester/trimethylsilyl ether derivative of 11-dehydro-TxB2 were investigated. Collision-induced dissociation mass spectra of the most intense parent ion in the high-mass region were taken. Collisionally activated decomposition mass spectra of the [C(12)-C(20)]+ ion of TxB2 and 2,3-dinor-TxB2 show an intense but not specific daughter ion, whereas the collison-induced dissociation mass spectrum of the [M - (C(16)-C(20)]+ ion of 11-dehydro-TxB2 results in the formation of numerous daughter ions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150304
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  • 188
    Digitale Medien
    Digitale Medien
    Quantification of urinary 3-hydroxyisovaleric acid using deuterated 3-hydroxyisovaleric acid as internal standard (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 652-656 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Deficiency of biotin at the tissue level can be assessed indirectly by measuring the urinary excretion of 3-hydroxyisovaleric acid. This paper describes the application of an improved method of quantifying urinary 3-hydroxyisovaleric acid using unlabeled and uniformly deuterated 3-hydroxyisovaleric acid. These compounds were synthesized by a modification of the lithioacetic acid method for generation of beta-hydroxy acids. Elemental analysis, nuclear magnetic resonance, gas chromatographic and gas chromatographic/mass spectrometric data demonstrated that the compounds are greater than 95% pure. Mass spectrometry confirmed the identity of the unlabeled compound, demonstrated that the deuterated compound is uniformly labeled, and offered insight into the pattern of mass fragmentation. The method for determination of the concentration of 3-hydroxyisovaleric acid in rat urine uses gas chromatographic/mass spectrometric quantification of the di-trimethylsilyl derivative with the deuterated compound as the internal standard. Results provide evidence that this method is more accurate than a previously published method that did not utilize the unlabeled and deuterated standards.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180903
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  • 189
    Digitale Medien
    Digitale Medien
    Metabolic dissimilarity between (9,12,12-2H)cortisol and natural cortisol in vivo. Can deuterated cortisol be used for the measurement of the urinary cortisol production rate? (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 662-667 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metabolism of deutrated cortisol (9,12,12,-2H)cortisol, (2H3-F) was compared to that of radioactive cortisol (3H2-F) and natural cortisol, when these three compounds were administered simultaneously to an adrenalectomized piglet. The relative isotope dilution of tritium was determined from the specific activities of the main urinary neutral cortisol metabolites, tetrahydrocortisone (THE) and tetrahydrocortisol (THF), normalized to that of the cortisol mixture administered. To obtain a comparison of the isotope dilution of deuterium in the metabolites THE and THF to that in the cortisol mixture, the three steroids were converted to the common oxidation product 11-oxo-aetiocholanolone, and deivatized to the methoxime-tert-butyl-dimethylsilyl ether. The relative 2H-isotope dilution then was measured by gas chromatography/mass spectrometry. It was found that the specific activity of THE in the cumulative urine collections was similar to that of the cortisol mixture administered; the two-day value was, however, less. The specific activity of THF was slightly but significantly smaller than 1 (∼0.9) at all times. The relative 2H-isotope dilution in THE was slightly but significantly larger than one (∼1.1) at all times, whereas that in the THF was larger than 1.0 at 9 and 32 h or equal to 1.0 at 20 and 47 h of urine collection. When comparing the metabolism of the two tracer cortisol species the quotient of the 3H- and the 2H-isotope dilutions in THE and THF was smaller than 1.0. It can be concluded that (2H3)cortisol may be used for the determination of the cortisol production rate.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180905
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  • 190
    Digitale Medien
    Digitale Medien
    Direct analysis of different classes of surfactants in raw materials and in finished detergent formulations by fast atom bombardment mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 673-689 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The characterization of the components of a surfactant mixture is a challenge, since we are dealing with substances inherently difficult to purify or separate by any available chromatographic methods. The results of the present work provide evidence that with fast atom bombardment mass spectrometry it is possible to identify the single constituents of the different clases of tensides - non-ionic, anionic, cationic and amphoteric - directly in the mixture and in detergent formulations (shampoos). The method, which is based on unambiguous molecular weight determination of the single components, allows the definition of the exact distribution of oligomers in the surfactant mixture, and distinction of subtle variations in the detergent composition in finished formulations. The results obtained indicate that this technique is a powerful analytical tool which can be used as a rapid screen test for quality control.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180907
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  • 191
    Digitale Medien
    Digitale Medien
    Biotransformation of aliphatic formamides: Metabolites of (±)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide in ratsPresented in part at the 35th ASMS Meeting, Denver, Colorado, May 1987. (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 690-701 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The in vivo biliary and urinary metabolites of (±)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide (1) from male Wistar rats have been characterized by gas chromatography/mass spectrometry. In urine, non-conjugated metabolites included 1,1-diphenyl-3-butanone (4) and 3-methylamino-1,1, diphenylbutane (7). β-Glucuronidase liberated 4, 1,1-diphenyl-3-butanol (5), 1,1-diphenyl-3-butanone oxime (6), N-hydroxymethyl-N-(1-methyl-3, 3-diphenylpropyl) formamide (3), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone (11), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone oxime (12), N-methyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (8), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone (16), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanol (17), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone oxime (18), N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (14) and N-methyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (13). Most of the carbinolamide (3) decomposed in the gas chromatograph inlet to N-(1-methyl-3,3-diphenylpropyl) formamide (2) unless stabilized as a trimethylsilyl (TMS) derivative. In bile, compounds 1, 2, 3, 5, 6, 11, 12 and 16 were present as non-conjugated metabolites. β-Glucuronidase also liberated N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (9), and all of the previously listed compounds except 7. Trimethylsilylation of the conjugated bile fraction revealed the presence of an additional two compunds: N-hydroxymethyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (10) and N-hydroxymethyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (15). A stable carbinolamide metabolite standard was synthesized and the mass spectral fragmentations of its TMS derivative studied by tandem mass spectroscopy. This is the first report on stable carbinolamide metabolites of high-molecular-weight formamides.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180908
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  • 192
    Digitale Medien
    Digitale Medien
    Parent ion spectroscopy in the identification of advanced glycation products (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 713-718 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Advanced glycation products have been investigated by parent ion spectroscopy, employing B2/E = constant linked scans of furoyl ions obtained from hydrolysed glycated albumin and polylysine mixtures, without any extraction procedures. Using such an instrumental approach, together with exact mass measurements and collision spectroscopy, the identification of 2-(2-furoyl)-4-hydroxyl-1H-imidazole and 2-(2-furoyl)-4-carboxy-1H-imidazole among the advanced glycation products has been achieved.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180911
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  • 193
    Digitale Medien
    Digitale Medien
    Identification of long-chain fatty acids and alcohols from human cerumen by the use of picolinyl and nicotinate esters (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 719-723 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Human cerumen was hydrolysed with base and the constituents were examined as trimethylsilyl (TMS), methyl ester/TMS, picolinyl/TMS and nicotinate/TMS derivatives by gas chromatography and gas chromatography/mass spectrometry. A sample was also reacted with osmium tetroxide for double bond location. The major constituents were cholesterol, squalene and several series of long-chain fatty acids and alcohols. These latter compounds had chain lengths of 12-26 carbon atoms and were predominantly either straight-chain saturated or straight-chain unsaturated compounds. Saturated branched-chain acids with methyl groups predominantly on even-numbered carbon atoms were present but were less abundant. Unsaturated, branched-chain acids were also present. The major unsaturated acids contained unsaturation at the delta-6-position or were derived from these acids by chain elongation. The compounds were similar to those found in vernix caseosa. The mass spectra of picolinyl esters were, for the first time, shown to be capable of determining both the position of unsaturation and methyl branching in the same molecule.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180912
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  • 194
    Digitale Medien
    Digitale Medien
    Tandem mass spectrometry of leucine enkephalin and physalaemin using a hybrid instrument (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 727-732 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Daughter ion mass spectral data of [M + H]+ ions of leucine enkephalin and physalaemin, which were formed by fast atom bombardment, were obtained using an instrument of EBQQ configuration. In the case of leucine enkephalin, experiments were carried out in which the collision energy was varied and the collision gas pressure kept constant and vice versa. The results show that conditions can be established under which seuqence-relevant ions above m/z 200 are formed, as well as under which mainly immonium and acylium type ions are generated. Of possible interest for characterization of unknown peptides, when using hybrid instruments, are the mid-chain cleavage ions, which, at a constant argon gas pressure of 5 × 10-6 mbat, were found to maximize at around 30 eV collision energy. Daughter ion mass spectral data are also presented for [M + H]+ ions of physalaemin (mol. wt 1264). Compared to data obtained for physalaemin on multisector instruments, our results indicate that the formation of mid-chain cleavage ions is clearly enhanced.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180914
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  • 195
    Digitale Medien
    Digitale Medien
    Characterization of virus infected cell cultures by pyrolysis/direct chemical ionization mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 757-760 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The supernatants of Vero cell cultures after infection with a herpes simplex virus or a poliomyelitis virus as well as a blank were analysed by pyrolysis/direct chemical ionization mass spectrometry (Py/DCI MS). Informative pyrogrammes were obtained and used for characterization of viral proteins by applying pattern recognition methods. Differentiation of viral proteins was evaluated by analysing ‘blind’ samples. Herpes viruses could be classified correctly but the observed differences between the blank and the polio virus supernatants were too small for reliable classification of the polio viruses. Purification of the samples seems to be a prerequisite for further studies. The potential value of Py/DCI MS as a rapid non-invasive diagnostic method for viral meningoencephalitis is stressed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180919
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  • 196
    Digitale Medien
    Digitale Medien
    Fast atom bombardment combined with tandem mass spectrometry for analysis of a complex mixture of lipo-oligopeptides from Nocardia rubra cell wallskeletonPart of the results in this paper have been presented at the 36th ASMS Conference on Mass Spectrometry and Allied Topics, San Francisco, USA, p. 1285 (1988). (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 761-766 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Experimental variables in fast atom bombardment combined with tandem mass spectrometry based on low-energy collision-induced dissociation have been systematically invetigated in order to optimize parameters for analysis of synthetic lipo-oligopeptides. The parameters studied were matrix, ion polarity, collision gas, collision gas pressure and collision energy. The optimal parameters recommended in this study have been applied to the N-terminal amino acid seuquence determination of lipopeptide obtained from Nocardia rubra cell wall skeleton. Daughter and parent ion experiments with negative ion fast atom bombardment combined with tandem mass spectrometry have proven to be very useful for structure elucidation of a complex mixture of lipo-oligopeptides.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180920
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  • 197
    Digitale Medien
    Digitale Medien
    The determination of atmospheric bis (chloromethyl) ether by gas chromatography/tandem mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 775-779 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The technique of gas chromatography/tandem mass spectrometry is applied to the analysis of bis(chloromethyl) ether in laboratory and production environments. A selected reaction monitoring method is shown to yield superior sensitivity and selectivity to previous methods. A detection limit of ∼1 ppt is established even for chemically complex atmospheres which have proved intractable by previous techniques.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200180922
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  • 198
    Digitale Medien
    Digitale Medien
    Sequence analysis of unprotected tri-deoxyribonucleoside diphosphates by 252Cf-plasma desorption mass spectrometryThis paper is part III of a series ‘252Cf-Plasma Desorption Mass Spectrometry of oligonucleotides’. Part II corresponds to Ref. 12. (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 83-90 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The negative Plasma Desorption Mass Spectra of ten unprotected tri-deoxyribonucleoside diphosphatesHereafter termed tri-deoxyribonucleotides. have been observed and analysed in detail. They all exhibit molecular ions as well as a characteristic fragmentation pattern. The ten trinucleotides selected were chosen in order to understand, in terms of sequence, the main features of the experimental spectra. It is shown that the structure and the sequence of the oligomers can be rapidly and easily derived from their PD Mass Spectrum.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140206
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  • 199
    Digitale Medien
    Digitale Medien
    Redox reactions occurring during secondary ion mass spectrometry of some heteroanthracycline antitumor antibiotic precursors (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 91-96 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Positive and negative secondary ion mass spectra of the title compounds were produced by bombardment of solid deposits by 13 and 23 KeV cesium ions, respectively, and analyzed with a time-of-flight mass spectrometer. In addition to familiar protonation and alkali (mainly sodium) ion addition processes observed in the positive ion spectra and proton abstractions in the negative ion spectra (which enable determination of molecular weight) there is evidence from both spectral modes for oxidation-reduction processes in which species such as [M - H]+, [M - H + Na]+. and [M + 1]- are formed. It is argued that these may be formed rapidly from pre-associated molecules during bombardment/ionization rather than as a result of radiation damage. Sodium ion addition is apparently facilitated by the presence of electron pair donor groups, especially if chelation is possible.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140207
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  • 200
    Digitale Medien
    Digitale Medien
    Isotope effect in negative ion chemical ionization mass spectrometry of deuterium labelled lormetazepam (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 257-261 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This study identified the reason for the poor quantification of Iormetazepam-TMS (1) using negative ion chemical ionization with lormetazepam-1,1,1-2H3-TMS (2) as an internal standard. Mass spectra of lormetazepam and its deuterium labelled compounds determined at various ion source temperatures (100-250°C) gave almost the same behaviour for 1 and lormetazepam-3′,4′,5′,6′-2H4-TMS (3) but a different one for 2, suggesting that the poor quantification was due to an isotope effect. This was confirmed by the findings that the ratios of ion currents of the base peaks of 1 and 3 were independent of the ion source temperature but those of 1 and 2 varied markedly with it. This phenomenon was also observed in the mass fragmentography of the molecular ion, although to a lesser degree than that of the above fragment. In both positive ion chemical ionization and electron impact ionization modes, no isotope effect arose because there was no corresponding fragment to cause the isotope effect.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200140603
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