Application of factor analysis to spectroscopic methods

A computer program has been developed to perform factor analysis and target testing on spectroscopic data. The program offers advantages over other software available on the PC in its ability to work with data matrices of a size limited only by memory and disk space on the computer, and the inclusion of target testing are iterative target testing routines. The program works with numbers of twice the precision of other software and evidence is presented of the improved accuracy of the calculations. The application of factor analysis to the UV-Vis spectra of a series (quaternary mixtures of transition metal ions is shown. The number of ions in the system is determined and the identities of the ions assigned using target testing. The effect of inadequate sampling intervals of the data is discussed. Factor analysis is also shown applied to temperature programmed pyrolysis mass spectrometry (TPPy-MS) data where multiple factors are found to arise from single component. The spectra of three substituted ferrocenes are giver 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic anhydride ferrocene, l-l'(2,4-dichlorobenzoyl) ferrocene, and 3,4-dichlorobenzoyl ferrocene. The source of the multiple components from each of the samples is discussed and used to propose pyrolysis and fragmentation mechanisms. The sensitivity of the factor analysis technique is exemplified by identification of factors due to contaminated source; improper calibration, adsorption effects within the source and bias in the measurement of mass spectra. The identification of components within mixtures is shown using target testing and the isolation of unknown components demonstrated using both accepted and novel methods of iterative target testing. The properties of the new methods of iterative target testing are investigated. The application of the techniques developed is show using unknown samples analysed by normal analytical techniques. The results of the analysis showed broad agreement with the normal analysis, though the factor analysis indicated the presence of a component not observed in normal analysis and also showed incorrect assignment of another.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Greenwich

Year dc:date.issued

1992

Author dc:creator

• Brockwell, Timothy Graham

Advisor dc:contributor.advisor

• Metcalfe, Edwin

• QC Physics
• QD Chemistry

Language dc:language

en