2ND-ORDER MULTIVARIATE CURVE RESOLUTION APPLIED TO THE FLOW-INJECTIONANALYSIS OF MIXTURES OF AMINO-ACIDS

A flow injection system with diode-array multi-wavelength spectrophoto metric detection was used to generate second order data. The system wa s applied to monitoring the reaction between amino acids (lysine and p roline) and 1,2-naphthoquinone-4-sulfonate (NQS) to give the correspon ding derivatives. The sample injection produced a pH gradient which al lowed the discrimination of the time profiles of the different amino a cid derivatives. Each amino acid gave a FIA response which was arrange d in a data matrix whose chemical rank was higher than one (more than one spectrophotometrically active species was present in the reaction system). The method was applied to the simultaneous determination of L ys and Pro by second order multivariate curve resolution, obtaining a global quantification error of 0.36%. The analysis of one of these ami no acids in presence of the other as interference by using a pure stan dard (without any information about the interference) was also studied . In this case, errors in the quantification were of 2.75 and 3.0% for Lys and Pro, respectively.