Application Of Chemometrics To The Analysis Of Multicomponent Systems

The basic feature of modern analytical chemistry is instrumentation of measurement and diversification of information. With the development of modern hyphenated apparatus and related chemometric methods, powerful techniques and extensive prospects are provided to deal with complex chemical systems. This reseach aims at rapidly analyzing real multicomponent samples qualitatively and quantitatively using chemometric resolution methods.In this paper, the author utilized UV-visible and fluorescence spectroscopy combined with chemometrics methods, and did some work in the research of multicomponent systems. Studies presented in the thesis primarily deal with the following aspects:In the second chapter, a method named OSCWPTPLS approach based on partial least square (PLS) regression with orthogonal signal correction (OSC) and wavelet packet transform (WPT) as pre-processed tools was developed for resolving the mixture of Fe(â…¢),Al(â…¢) and Be(â…¡) with severe overlapping spectra without prior separation. The method combines the ideas of OSC and WPT with PLS regression for enhancing the ability in the extraction of characteristic information and the quality of regression. The three metal ions determined can react with chromazurol S and cetyl pyridinium bromide (CPB) in the potassium hydrogen phthalate-sodium hydroxid buffer solution at pH=5.6 to form ternary coloured complexes having high sensitivity and poor selectivity. A program named POSCWPTPLS was designed to perform the relative calculation. Experimental results showed the OSCWPTPLS method was successful and better than PLS methods. In addition, this method was also used in the fourthin chapter as a preprocessed tool for the simultaneous fluorespectrophotometric determination of tryptophan, tyrosine and phenylalanine with overlapping peaks, and satisfactory results were obtained.In the third chapter, a DOSC-WPT-PLS method based on partial least square-s (PLS) regression with direct orthogonal signal correction (DOSC) and wavel et packet transform (WPT) as preprocessed tools was proposed for the simulta neous fluorespectrophotometric determination of catechol, resorcinol and hydroq uinone with overlapping peaks. The method combines DOSC and WPT with P LS regression for enhancing the ability in the extraction of characteristic infor mation and the quality of regression. In this case, simultaneous fluorespectroph otometric determination of catechol, resorcinol and hydroquinone of synthetic u nknown samples was fulfilled based on processing the data of their fluorescen e spectra. Three kinds of chemometric methods (DOSC-WPT-PLS, WPT-PLS a nd PLS) were applied in this study for comparison. The relative standard error s of prediction (RSEP) obtained for all components using DOSC-WPT-PLS,WP T-PLS and PLS were 4.3%,7.7% and 11.5%, respectively. Experimental results demonstrated that the DOSC-WPT-PLS method had the best result among the three methods and was successfully appliedin the determination of the content s of catechol, resorcinol and hydr-oquinone in tap water. Their recoveries wer e 99%-107%,95%-108% and 98%-104%, respectively. Also in the fifthchapter, themethod was proposed for the simultaneous fluorespectrophotometric determi nation of Vitamin B1, vitamin B2 and vitamin B6 with overlapping fluorescenc e spectra, and the result was satisfactory.