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

Abstract A new method for simultaneous determination of eight vitamin E isomers including α-, β-, γ-, and δ-tocopherol and α-, β-, γ-, and δ-tocotrienol by ultra-performance convergence chromatography (UPC 2 ) equipped with a diode array detector was reported. They were separated on a BEH 2-EP column (3.0 mm × 100 mm, 1.7 μm) using gradient elution (95:5–80:20) with a mobile phase consisted of CO 2 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.