Simplified sample preparation and rapid detection by RP‐HPLC/FLD of tocopherols and tocotrienols in margarines: Preliminary screening of plant fats—potential quality markers

Abstract

A simplified, rapid, and accurate method for sample preparation and determination of tocopherols and tocotrienols (vitamin E) in margarine was developed. For this purpose, 28 margarines with different amounts of fat (20, 39, 60, 70, 75, and 80%) and of two types (spreads and cooking fats) were used. Sample preparation was reduced to a limited number of rapid steps: weighting, melting, diluting, vortexing, and centrifugation, following which the samples were directly injected to the HPLC system. The developed method prevented analyte losses and was characterized by good repeatability and reproducibility (1.4–5.5% and 2.9–9.9%, respectively) and accuracy range (97.9–101.2%) as well as recovery of tocopherols and tocotrienols when compared to the saponification method (89.4–104.4%), without any interference of other compounds from the margarine matrix and thus reduced the risk of potential measurement errors. Fat content in margarine samples did not have any negative impact on precision, accuracy or recovery of tocopherols and tocotrienols. Concentrations of tocopherol (T) and tocotrienol (T3) homologues in margarine samples depended on the fat content and ranged from 2.65–26.27 (α‐T), 0.02–0.70 (β‐T), 4.23–23.60 (γ‐T), 0.08–2.34 (δ‐T), 0.39–15.05 (α‐T3), 0.00–1.36 (β‐T3), 0.49–20.08 (γ‐T3), and 0.00–5.28 mg/100 g (δ‐T3).Practical applications: The necessity to ensure high quality and nutritional value of food products results in the need to develop new high quality analytical methods. This paper describes a simple, rapid and accurate method of sample preparation, preventing analyte losses, and facilitating fast determination of all tocopherol and tocotrienol homologues by RP‐HPLC/FLD in margarines containing different amounts of fat (20, 39, 60, 70, 75, and 80%). Margarines are a significant source of vitamin E in our daily diet; therefore, the developed method could be implemented in industry both in routine control and to improve nutrition information about the product provided on the label and also as the first screening test to assess the possible origin of the fat used for margarine production (with tocopherols and tocotrienols as quality markers).Tocopherol and tocotrienol homologues (α, β, γ, and δ) in margarine samples with different amounts of fat (20–80%) were successfully separated by using RP‐HPLC/FLD. The developed method is characterized by ease of implementation, speed, reliability, prevents analyte losses (quantification errors), saves solvents, and does not affect quality of analysis. As the developed method has been simplified and accelerated (reducing time and costs), it may be applied as the preliminary screening test to assess the possible origin of the fat used for margarine production (tocopherols and tocotrienols as quality markers).