Simultaneous Determination Of Tocopherols Research Articles

Simultaneous Determination of Tocopherols, Phytosterols, and Squalene in Vegetable Oils by High Performance Liquid Chromatography-Tandem Mass Spectrometry

Vegetable oil is one of the principal sources of minor bioactive substances such as tocopherol, phytosterol, and squalene. In order to obtain the distribution of these substances in vegetable oil, this study developed and validated high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) method for the simultaneous analysis of tocopherols (α-, β-, γ-, and δ-tocopherol), phytosterols (β-sitosterol, stigmasterol, brassicasterol, and campesterol), and squalene in vegetable oils. An automatic gel permeation chromatography (GPC) system was used to remove triglycerides from oils, avoiding the heat treatment of traditional saponification. Method validation revealed the accuracy and reliability of this method. The current approach achieved the successful separation of β- and γ-tocopherol, which solved the problem of coelution and inaccurate quantification for β- and γ-tocopherol in previous study. Additionally, this method was applied to detect tocopherols, phytosterols, and squalene in 9 categories of vegetable oils.

Simultaneous determination of tocopherols, carotenoids and phytosterols in edible vegetable oil by ultrasound-assisted saponification, LLE and LC-MS/MS

A method was developed to simultaneously determine eight bioactive compounds in edible oil based on ultrasound-assisted saponification, liquid-liquid extraction and liquid chromatography coupled with tandem mass spectrometry. Central composite design was employed to optimize ultrasonic temperature and time of saponification. Sample treatment was conducted by ultrasound-assisted saponification at temperature of 75 °C for 40 min. Limits of detection and limits of quantification ranged from 2.0 to 3.2 and from 6.1 to 10.0 ng/mL, respectively. Linear correlations were obtained (R2 > 0.99) and the recoveries at three spiked levels were between 81.7% and 112.0%. This method was employed to determine eight compounds in camellia oils and olive oils. As results, the contents of stigmasterol, δ-tocopherol, γ-tocopherol, β-carotene and lutein in camellia oils were significantly higher than those in olive oils (p < 0.05). The proposed method can be successfully used to determination of these eight active compounds in camellia oil and other edible oils.

Simultaneous determination of tocopherols and tocotrienols in vegetable oils by GC-MS

A simple and rapid gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the simultaneous determination of α-, β-, γ- and δ-tocopherols and α-, β-, γ- and δ-tocotrienols in vegetable oils.

Validated RP-HPLC Method for Simultaneous Determination of Tocopherols and Tocotrienols in Whole Grain Barley Using Matrix Solid-Phase Dispersion

The vitamers of vitamin E such as α-, β-, γ-, and δ-tocotrienol and α-, β-, γ-, and δ- tocopherol are important phytochemical compounds with antioxidant activity and with potential benefits for human health. A high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method was validated for their determination in whole grain barley samples. Tocol extraction was performed by an optimized matrix solid-phase dispersion (MSPD) protocol with neutral alumina (0.5 g) as the dispersion agent and methanol (5 mL) as the elution solvent. The analytical column was an Eclipse XDB C18 column (150 × 4.6 mm, 5 μm) and it was operated at room temperature. Mobile phase was consisted of methanol/acetonitrile/i-propanol (55:40:5 v/v %) and the elution was isocratic at a flow rate of 0.8 mL/min. Total analysis time was 12 min, and the detection of the tocols was performed with a fluorimetric detector where the excitation and emission wavelengths were set at 295 and 335 nm, respectively. Method validation was performed by means of intra-day (n = 5) and inter-day accuracy and precision (n = 8), sensitivity, and linearity. The linear regression coefficient (R2) was higher than 0.99. The recoveries of the tocols from barley samples with the proposed extraction method were in an acceptable level (74–91 %) where the relative standard deviation ranged from 4.2 to 15.0 %. Limits of detection (LODs) and limits of quantification (LOQs) varied from 0.03 to 0.11 mg kg−1 and 0.11 to 0.34 mg kg−1, respectively.

Simultaneous determination of tocopherols, retinol, ester derivatives and β-carotene in milk- and soy-juice based beverages by HPLC with diode-array detection

A simple, sensitive and accurate HPLC method has been developed and validated for the simultaneous determination of α-tocopherol, γ-tocopherol, δ-tocopherol, α-tocopheryl acetate, retinyl palmitate, retinol and β-carotene in milk- and soy-juice based beverages. The assay was performed using a Luna RP-C18 column with methanol: THF: water (67:27:6, v/v/v) as mobile phase, at a flow rate of 0.8 mL/min. Diode-array detector was set at 290 nm for tocopherols, 325 nm for retinols and 440 nm for β-carotene. The method developed and validated is simple and shows good linearity, precision, accuracy and sensitivity and was applied to the analysis of different commercial mixed beverages. The profile of these compounds was different in milk- or soy-juice. Tocopheryl acetate and retinyl palmitate are added in all milk-juice and free γ- and δ-tocopherols are characteristic of soy-juice samples. β-carotene is present in both types of mixed beverages.

Validation of a method for simultaneous determination of tocopherols and tocotrienols in cereals using Normal Phase HPLC

A method for the simultaneous determination of tocols (α-, β-,γ-, δ-tocopherols and α-, β-,γ-, δ-tocotrienols) in cereals using Normal Phase-HPLC (Merck; column LiChroCART 250-4, Lichrospher Si 60, 5 μm) with fl uorescent detection (Ex290 nm/Em350 nm) was validated. A mixture of hexane, ethyl acetate and acetic acid (97.3:1.8:0.9, v/v/v) was used as the eluent (1.6 ml/min). The analyses were performed after spectrophotometric standardization of standard ethanol solutions. The residual coeffi cients of variation for the regression equation y= ax 2 + bx + c were 0.001-3.8%, with r 2 >0.999. The limit of quantitation was 0.05 mg/kg, the upper limit of determination range from 40 to 60 mg/kg, repeatability 6.2-11.8%, and reproducibility 8.7-18.4%. Uncertainty of the method (P≤0.05), estimated for the analyses performed in replicate, ranged from 28.9 to 85.9% for the tocol concentration of 0.05-0.80 μg/ml and from 14.7 to 27.3% for the concentrations above 0.80 μg/ml. Recovery was 93.3-103.1%. The analytical method described is precise, fast and inexpensive.

Simultaneous Determination of Tocopherols and Tocotrienols in Hazelnuts by a Normal Phase Liquid Chromatographic Method

A normal-phase high-performance liquid chromatography (NP-HPLC) method for the determination of tocopherols and tocotrienols in hazelnuts is reported. Three extraction procedures (with and without saponification) were assayed; the best results were obtained with a simple solid-liquid extraction procedure. Chromatographic separation was achieved using an Inertsil 5 SI column using isocratic elution with hexane/1,4-dioxane (95.5:4.5, v/v) at a flow rate of 0.7 mL/min. The effluent was monitored by a series arrangement of a diode-array followed by a fluorescence detector. All compounds were separated in a short period of time (17 min). The method proved to be rapid, sensitive, reproducible and accurate, allowing the simultaneous determination of all vitamin E homologues.

Simultaneous determination of tocopherols, ubiquinols, and ubiquinones in blood, plasma, tissue homogenates, and subcellular fractions

A fast single-step lipid extraction procedure and high-performance liquid chromatography with in-line uv and electrochemical detection are used for the simultaneous quantitative determination of tocopherols, ubiquinols, and ubiquinones in blood, plasma, tissue homogenates, and subcellular fractions. The compounds of interest can be quantitatively extracted into hexane from a sodium dodecyl sulfate-treated aqueous homogenate after precipitation of protein by addition of an equal volume of ethanol. α-, γ-, and δ-Tocopherol, ubiquinol 9, ubiquinol 10, and ubiquinones 9 and 10 can be well separated on a reversed phase column. Ubiquinones are detected at 275 nm by the uv detector, and ubiquinols and tocopherols by the electrochemical detector in the oxidative mode. Quantitation is done by comparing chromatographic peak heights to those of a standard solution containing known amounts of tocopherols, ubiquinols 9 and 10, and ubiquinones 9 and 10, analyzed under identical conditions. The high sensitivity of the electrochemical detection allows operation at low potentials (+0.5 V) with low detector response, but high selectivity for the easily oxidizable tocopherols and ubiquinols and decreased baseline noise. The uv detection limits the overall sensitivity of the procedure to 2 pmol ubiquinone, corresponding to 0.1 μ m ubiquinone in the lipid extract. The ranges of values obtained for rat and guinea pig tissues, for rat liver mitochondria, and for blood and plasma from rats and humans are given.

Application of a shift reagent in nuclear magnetic resonance spectroscopy of esters. An approach for simple identification and simultaneous determination of tocopherols

Methode zur genaueren Identifizierung von Phenolacetaten wie Kresyl- bzw. Tocopheryl-Acetaten durch NMR mit Shift-Reagenz Eu(DPM)3 und gleichzeitiger Gehaltsbestimmung der Tocopherole in der Mischung.