Analysis of vitamin E derivatives in serum using coordinated ion spray mass spectrometry

Ultrafast determination of vitamin E using LC–ESI–MS/MS for preclinical development of new nutraceutical formulations

Aim: We proposed a rapid and high quality method to determine α-tocopherol (α-T) in different biopharmaceutical samples using liquid chromatography-diode array detector on-line ESI–MS/MS. Materials & methods: A working standard solution of α-T and internal standard, phenyl-5,7-dimethyl-d6-α-tocopherol, were used for optimization and validation of the method. Levels of α-T in nanoemulsions, serum and plasma samples were evaluated. Results & conclusion: Precision (1% for retention time, 5% for peak area and 3% for relative peak area), linearity range (among 0.625–20.0 μg ml-1), LOD and LOQ, accuracy and matrix effect were studied. The validated chromatographic method is presented as valuable analytical tool for the determination of α-tocopherol in loaded drug delivery systems and in biodistribution levels in blood samples.

GC-MS and LC-MS approaches for determination of tocopherols and tocotrienols in biological and food matrices

Tocopherols and tocotrienols, widely described as vitamin E derivatives, have been proven to take part in a number of important biological functions. Among them, antioxidant properties had been investigated and documented in the literature. Since tocochromanols have revealed their plausible beneficial impact on several pathological processes, such as cancerogenesis or cognitive impairment diseases, there is a growing interest in quantitative determination of these compounds in biological fluids, tissues and plant organs. However, due to vitamin E chemical features, such as lipophilic and non-polar characteristics, quantitative determination of the compounds seems to be problematic. In this paper we present current analytical approaches in tocopherols and tocotrienols determination in biological and food matrices with the use of chromatographic techniques, especially gas chromatography (GC) and high performance liquid chromatography (HPLC) coupled with mass spectrometry. Derivatization techniques applied for GC-MS analysis in the case of tocol derivatives, especially silylation and acylation, are described. Significant attention is paid to ionization process of tocopherols and tocotrienols.

A review of characterization of tocotrienols from plant oils and foods

Tocotrienols, members of the vitamin E family, are natural compounds found in a number of vegetable oils, wheat germ, barley and certain types of nuts and grains. Vegetable oils provide the best sources of these vitamin E forms, particularly palm oil and rice bran oil contain higher amounts of tocotrienols. Other sources of tocotrienols include grape fruit seed oil, oats, hazelnuts, maize, olive oil, buckthorn berry, rye, flax seed oil, poppy seed oil and sunflower oil. Tocotrienols are of four types, viz. alpha (α), beta (β), gamma (γ) and delta (δ). Unlike tocopherols, tocotrienols are unsaturated and possess an isoprenoid side chain. A number of researchers have developed methods for the extraction, analysis, identification and quantification of different types of vitamin E compounds. This article constitutes an in-depth review of the chemistry and extraction of the unsaturated vitamin E derivatives, tocotrienols, from various sources using different methods. This review article lists the different techniques that are used in the characterization and purification of tocotrienols such as soxhlet and solid-liquid extractions, saponification method, chromatography (thin layer, column chromatography, gas chromatography, supercritical fluid, high performance), capillary electrochromatography and mass spectrometry. Some of the methods described were able to identify one form or type while others could analyse all the analogues of tocotrienol molecules. Hence, this article will be helpful in understanding the various methods used in the characterization of this lesser known vitamin E variant.

Comparison of reversed-phase liquid chromatography–mass spectrometry with electrospray and atmospheric pressure chemical ionization for analysis of dietary tocopherols

ESI and APCI ionization techniques in both negative and positive ion modes were evaluated for simultaneous LC-MS analysis of the four tocopherol homologues (alpha, beta, gamma and delta). The ESI and APCI ionization of tocopherols in positive ion mode was not efficient and proceeded via two competitive mechanisms, with the formation of protonated pseudo-molecular ions and molecular ions, which adversely influenced the repeatability of MS signal. Ionization in negative ion mode in both ESI and APCI was more efficient as it only produced target deprotonated pseudo-molecular ions. The APCI in negative ion mode showed larger linearity range, lower detection limits and was less sensitive to the differences in chemical structure of analytes and nature of applied solvents than negative ion ESI. Negative ion APCI was, therefore, chosen for the development of LC-MS method for simultaneous determination of the four tocopherols in foods. A baseline separation of the tocopherols was achieved on novel pentafluorophenyl silica-based column Fluophase PFP. The use of methanol-water (95:5, v/v) as a mobile phase was preferable to the use of acetonitrile-water due to considerable gain in MS signal. The limits of quantifications were 9 ng/mL for alpha-tocopherol, 8 ng/mL for beta- and gamma- and 7.5 ng/mL for delta-tocopherol when 2 microL was injected. This method was successfully applied to determination of tocopherols in sunflower oil and milk.

Determination of tocopherols and tocotrienols in cereals by pressurized liquid extraction–liquid chromatography–mass spectrometry

A rapid analytical method including pressurized liquid extraction (PLE) and liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) has been developed for the determination of tocopherols and tocotrienols in cereals. The pressurized liquid extraction parameters were optimized in order to maximize the extraction efficiency. The use of methanol as extraction solvent at a temperature of 50 degrees C and a pressure of 110 bar, using one cycle of extraction with a static time of 5 min, provided the best results. A good LC separation was achieved using a C(18) column and a solution of 6.0 mM ammonia in methanol/water (97:3, v/v) as the mobile phase at a flow rate of 0.2 mL min(-1). MS coupling with an ESI interface in the negative ion mode was used as the detection technique. In the present work, it is shown that the addition of a base to the mobile phase is required to enhance the ionization of tocopherols and tocotrienols in negative ion mode electrospray ionization. The applicability of the method to cereal samples was confirmed. The reproducibility of the procedure was good, with relative standard deviations in the 6-10% range. The recoveries of added tocopherols from cereal samples ranged from 91 to 109%.