Cyclic voltammetric simultaneous determination of oxidizable amino acids using multivariate calibration methods

A voltammetric method for the simultaneous determination of oxidizable amin o acids (cysteine, tyrosine and tryptophan) is proposed. The method is base d on the analysis of multivariate data, which consists of cyclic voltammogr ams registered in the range from 400 to 1100 mV with a graphite-methacrylat e composite electrode, by using multivariate calibration methods. Cyclic vo ltammograms of pure standards of these oxidizable amino acids show characte ristic shapes. Thus, the resolution of mixtures of them by multivariate cal ibration lies in the differences in their voltammograms. The main difficult ies encountered in these analyses are the high degree of overlapping and th e lack of bilinearity of voltammetric data. The prediction abilities of pri ncipal component regression (PCR) and partial least squares regression (PLS ) were assayed to the analysis of oxidizable amino acids in a series of syn thetic samples. The quantification of cysteine and tryptophan was especiall y satisfactory since they are the most characteristic amino acids. (C)2000 Elsevier Science B.V. All rights reserved.