Simultaneous analysis of eight vitamin E isomers in Moringa oleifera Lam. leaves by ultra performance convergence chromatography

A new method for simultaneous determination of eight vitamin E isomers including alpha-, beta-, gamma-, and delta-tocopherol and alpha-, beta-, gamma-, and delta-tocotrienol by ultra-performance convergence chromatography (UPC2) equipped with a diode array detector was reported. They were separated on a BEH 2-EP column (3.0 mm x 100 mm, 1.7 mu m) using gradient elution (95: 5-80: 20) with a mobile phase consisted of CO2 and methanol: isopropanol (1: 1, v/v), back pressure of 1800 psi, flow rate of 1.5 ml/min and detection at 294 nm. The results showed good linearity (R-2 = 0.9990-0.9998) and high resolution (1.48-7.67). Limits of detection (LOD) and quantification (LOQ) ranged from 23-49 ng/L and 70-150 ng/L, respectively. Relative standard deviations (RSD) for repeatability and reproducibility were 0.62-3.16% and 0.82-3.34%, respectively. Moreover, this method was successfully applied to analysis the vitamin E isomers in Moringa oleifera leaf samples. (C) 2016 Elsevier Ltd. All rights reserved.