Low-temperature cleanup with solid-phase extraction for the determination of polycyclic aromatic hydrocarbons in edible oils by reversed phase liquid chromatography with fluorescence detection

Abstract

Low-temperature cleanup, which is a simple and cost-efficient sample preparation technique that allows the convenient treatment of multiple samples simultaneously, was developed in conjunction with solid-phase extraction (SPE) cleanup for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in refined and used edible oil samples by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Samples are extracted with a small amount of organic solvent and most of lipids in the extract were removed by low-temperature cleanup. SPE cartridge was used to further cleanup prior to HPLC-FLD analysis. Optimum extraction of low-temperature cleanup was achieved when using two extractions with a 4:1 (v/v) mixture of acetonitrile: acetone as the extraction solvent, freezing at between -18 °C and -25 °C for 24 h and then cleanup with an Alumina-N SPE cartridge. The PAH recoveries were 45.9-118.5%, with limit of detection (LOD) and limit of quantitation (LOQ) values of 0.13-3.13 μg/kg and 0.25-6.25 μg/kg across the 16 tested PAHs, respectively. The validated method was successfully applied for the determination of PAHs in reference materials of olive oil and real refined and used edible oil samples.

Keywords: Edible oil; HPLC-FLD; Low-temperature cleanup; PAHs; Solid-phase extraction.