Chemometrics for the resolution of co-eluting peaks of β- and γ-tocopherols in RP-HPLC: Determination in edible oils and dietary supplements

This paper deals with the quantification of β- and γ-tocopherol by RP-HPLC, using a C18 column as stationary phase, and MeOH:H2O (90:10, v/v) as mobile phase (flow rate, 2 mL min−1). Both analytes appear together in the same chromatographic peak and, as consequence, a partial least squares (type PLS-1) chemometric method has been developed to analyze them separately. Different calibration matrices have been done with the fluorescence spectra, excitation and emission, absorbance and derivative absorbance spectra, obtained across the peak or in the peak apex. The matrix of data constructed with the derivative absorbance spectra obtained in the peak apex is the one that gives best results. The method has been successfully applied to edible oils and dietary supplements. No pre-treatment of the samples was needed, only a dilution in 2-propanol was effected.