Chemometrics-assisted optimization of beta-/gamma-tocol separation on a c30 stationary phase in reversed-phase lc

This paper presents a chemometrics-assisted optimization study to improve the separation of tocopherol (-T) and tocotrienol (-TT) homologues on a C30 stationary phase in reversed-phase HPLC. The HPLC settings were optimized using a central composite design and the response surface methodology. Flow rate, column temperature, and mobile phase composition were chosen as independent variables. Peak resolution (Rs), analysis time (tR), and peak symmetries of the tocopherol isomers were chosen as response variables. Optimum performance in terms of Rs was obtained at a flow rate of 0.31 mL min?1, a temperature of 8.70 °C, and % B content (methyl tert-butyl ether: methanol: water, 80:18:2, v/v/v) in the mobile phase of 38.12%. The analysis of variance and regression analysis gave adjusted R2 values of 0.9841 for Rs, 0.9850 for tR-(?-T), 0.9853 for tR-(?-T), and 0.9204 for the peak symmetry of ?-T. This confirms the good agreement of experimental data with predicted values. The close eluting peaks of ?-/?-tocol could be baseline separated at the optimized conditions at a minimized analysis time. Empirical second-order polynomial models were derived that gave statistically high significances (P < 0.0001). Hence, the models can be successfully employed to predict the optimum separation conditions of co-eluting peaks of ?-/?-tocols. The optimized method was successfully applied to determine the individual tocol homologues in various cold pressed edible oils. Total contents ranged from 15 to almost 2600 mg tocol kg?1 oil.18-M-17Acknowledgements This article is supported financially by the Scientific Research Project Center of Karamanoglu Mehmetbey University (Project number 18-M-17). The authors would also like to thank the Scientific and Technological Research Council of Turkey (TUBITAK) under the 2219 Research Fellowship Program for International Postdoctoral stays for providing the financial scholarship support to carry out this research work