Simultaneous spectrophotometric determination of folic acid, pyridoxine, riboflavin, and thiamine by partial least-squares regression

A new method for the simultaneous spectrophotometric determination of folic acid, pyridoxine, riboflavin and thiamine based on total absorbance measurements and their processing by partial least square regression is proposed. The concentration ranges used to construct the calibration matrix were 1.02-14.3 mug mL(-1), 1.01-16.2 mug mL(-1), 1.02- 10.2 mug mL(-1) and 6.00-20.0 mug mL(-1) for folic acid, pyridoxine, riboflavin and thiamine, respectively. Estimated limits of detection were: folic acid 0.08 mug mL(-1), pyridoxine 0.45 mug mL(-1), riboflavin 0.09 mug mL(-1) and thiamine 0.17 mug mL(-1). The proposed methodology was checked by applying it to the analysis of a set of laboratory-made samples. It was shown that is possible to resolve complex mixtures of compounds even when they have strongly overlapped signals. The analytical results obtained were good in all cases.