Simultaneous Analysis of Vitamin E Isoforms in Food by LC-MS/MS

Vitamin E consists of α-, β-, γ-, δ-tocopherols (T) and their respective tocotrienols (T3), lipophilic compounds naturally occurring in plants. It plays an important role for human health due to vitaminic and antioxidant activities. Dietary intake of vitamin E mainly derives from vegetable fats and oils, even though cereals and meat products contribute too. The most common analytical methods employ normal phase chromatographic separation for the eight vitamin E isoforms, despite the weakness of the MS detection sensitivity [1]. The aim of the present study was to develop an extremely simple, rapid and sensitive LC-MS/MS method for the simultaneous determination of the eight isoforms of Vitamin E in food samples, using reverse phase chromatographic separation [2]. Tocopherols and tocotrienols were determined in pistachio, margarine, pork fillet and ventricina, a typical Italian cured meat. The chromatographic separation was carried out on a pentafluorophenyl (PFP) column and was achieved by an isocratic elution with MeOH/H2O acidified with TCA. The MS detection was performed on a QQQ instrument interfaced with APCI source operating in positive mode. A multiple reaction monitoring (MRM) method was employed to increase the sensitivity. Remarkable features of the method are: low detection (1–3 ngmL-1) and quantification limits (4–10 ngmL-1), wide linear ranges (5–15000 ngmL-1) and fastness of analysis (only 15 min). All the Vitamin E isoforms were found in pistachio raw nuts, margarine, pork fillet, and ventricina samples. Alpha-T was the most abundant isoform in pork fillet, ventricina and margarine, whereas, γ-T was main vitamin E constituent in pistachio raw nuts. The proposed LC–MS/MS method is suitable to expand the composition knowledge of the comprehensive vitamin E homologues in foodstuffs.