摘要:

AbstractThis is a first foray into the historical start and early years of chemometrics from about 1972 onwards. We have gathered interviews with three originators (Kowalski, Wold and Massart) as well as with a selected group of six other well‐known chemometricians who gradually became active in the 1970s (Christie, Clementi, Hopke, Martens, Brown and Deming). The interviews include amongst a host of subjective recollections a succinct record of the key historical literature as highlighted by the interviewees' own rankings of ‘earliest’ and ‘best’.A discussion of the most general commonalities in these interviews together with other historical material is presented in the second part of

ISSN:0886-9383    

DOI:10.1002/cem.1180040503

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractA survey of members of the U.K. QSAR Discussion Group has been made to determine the extent of use and development of chemometric and artificial intelligence (AI) methods in the analysis of multivariate quantitative structure–activity relationship (QSAR) data in the U.K. Chemometric methods were found to be well established in both industrial and educational establishments and there was significant method development occurring. AI methods were not employed to any great extent and the general level of interest in these techniques was low compared to chemometric methods. A requirement for more education in multivariate statistical methods and regression methods was indicated. A need for a user‐friendly, comprehensive, commercially available multivariate statistical package containing multivariate stability testing and regression diagnostic methods was identif

ISSN:0886-9383    

DOI:10.1002/cem.1180040504

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractAbstract factor analyses were performed on databases consisting of simulated samples from aqueous equilbria. The program COMPLEX was used to generate equilibrium species in a system of three reactant metals and five reactant bases. Reactant concentrations and pH were drawn from random–normal distributions so that sample data vectors comprised a multivariate log–normal distribution of equilibrium concentrations. In addition, sample groups were created containing different distributions for pH and reactant concentrations.Equilibrium species were shown to contain variance contributed by change in pH among samples as well as change in reactant concentrations. Factor modelling revealed the qualitative relationships among the species and how the relationships change with pH. Factors also revealed those reactants containing variance in the data matrix. In some cases, reactant variance obscured relationships between pH and the equilibrium species.Since factor modelling of a simulated data matrix revealed the expected chemical equilibrium interactions, a potentially powerful tool exists for investigating the effects of outliers and er

ISSN:0886-9383    

DOI:10.1002/cem.1180040505

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractMandarine essential oils are extracted from green unripened fruits as well as from red fruits at ripening, both oils having specific uses as natural additives in the food industry. Two processes of production, pressing and peeling, are currently adopted in their production. Capillary gas chromatography with flame ionization detection has been suggested as a sensitive method for the fractionation of volatile components of the essential oils. Principal component analysis was proposed as an exploratory chemometric method for the differentiation of essential oils from fruits at different degrees of ripening, taking into account the processes of production. Product–moment correlations between variables (concentrations of 17 components) were used as starting matrices and the explained variance was adopted as a criterion for eigenvalue selection. Bi‐plots and three‐dimensional plots of unrotated principal component scores were systematically used as well as those of orthogonally rotated factor scores. The 17 variables were reduced to four principal components, which explained 87% of the total variance. Projection on the first three eigenvectors of all data as unrotated component scores allowed for a tentative differentiation of 59 oils according to their degree of ripening. The two processes of production were also differentiated in a sample of 55

ISSN:0886-9383    

DOI:10.1002/cem.1180040506

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0886-9383    

DOI:10.1002/cem.1180040508

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0886-9383    

DOI:10.1002/cem.1180040502

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY