Method optimization for trans fatty acid determination by CZE-UV under direct detection with a simple sample preparation

Abstract

An alternative method for trans fatty acid (TFA) determination, expressed in elaidic acid, by capillary zone electrophoresis using UV-VIS direct detection (200 nm) with a simple sample preparation is proposed. The method optimization was through the 3² full factorial design with triplicate in the central point and the sample preparation comprised only a saponification step. The background electrolyte was composed of 12 mmol L⁻¹ of tetraborate buffer at pH 9, 12 mmol L⁻¹ of Brij 35, 33% methanol and 17% acetonitrile. A baseline separation of elaidic (C18:1t-9), oleic (C18:1c), linoleic (C18:2cc) and linolenic (C18:3ccc) acids within an analysis time of 4 minutes was achieved, taking into account the statistical approach based on response factor calculation using nonadecanoic acid (C19:1c) as the internal standard (IS). The method potentiality was successfully demonstrated in the determination of TFAs in cake mix, wafer stick, coconut donut and guava paste biscuit samples and presented no significant difference when compared to the gas chromatography classical method within the 95% confidence interval. In addition, the method offered inherent advantages such as no lipid extraction step, higher throughput, lower analytical cost, no need for specific columns and use of small amounts of organic solvents and reagents.