Simultaneous spectrophotometric determination of folic acid, thiamin, riboflavin, and pyridoxal using partial least-squares regression method

A multivariate calibration method (Partial least squares regression, PLS-1), is applied to the simultaneous determination of folic acid (vitamin B-0), thiamin (vitamin 131), riboflavin (vitamin 132) and pyridoxal (vitamin 136), in artificial mixtures by ultraviolet/visible absorption spectrophotometry. The concentration ranges used to construct the calibration matrix are 0.4-15.0, 0.7-30, 0.2-11 and 0.8-30 mug mL(-1) for vitamin B-0, B-1, B-2 and B-6 respectively. The absorption spectrum of the quaternary mixtures is used to perform the optimization of the calibration matrices by the PLS-1 method. For this purpose a cross-validation procedure for estimating the number of principal components in a matrix, is used. Satisfactory recovery values are obtained in most of the quaternary samples analyzed. Mean recovery values for these vitamins are 95-105%.