Determination of benzo[a]pyrene in edible oils using phase‐transfer‐catalyst‐assisted saponification and supramolecular solvent microextraction coupled to HPLC with fluorescence detection

Abstract

For the analysis of edible oils, saponification is well known as a useful method for eliminating oil matrices. The conventional approach is conducted with alcoholic alkali; it consumes a large volume of organic solvents and impedes the retrieval of analytes by microextraction. In this study, a low-organic-solvent-consuming method has been developed for the analysis of benzo[a]pyrene in edible oils by high-performance liquid chromatography with fluorescence detection. Sample treatment involves aqueous alkaline saponification, assisted by a phase-transfer catalyst, and selective in situ extraction of the analyte with a supramolecular solvent. Comparison of the chromatograms of the oil extracts obtained by different microextraction methods showed that the supramolecular solvent has a better clean-up effect for the unsaponifiable matter from oil matrices. The method offered excellent linearity over a range of 0.03- 5.0 ng mL (r > 0.999). Recovery rates varied from 94 to 102% (RSDs <5.0%). The detection limit and quantification limit were 0.06 and 0.19 μg kg , respectively. The proposed method was applied for the analysis of 52 edible oils collected online in China; the analyte contents of 23 tested oil samples exceeded the maximum limit of 2 μg kg for benzo[a]pyrene set by the Commission Regulation of the European Union.

Recent Advances in Sample Preparation and Chromatographic/Mass Spectrometric Techniques for Detecting Polycyclic Aromatic Hydrocarbons in Edible Oils: 2010 to Present

“…Saponification is an effective method for eliminating these compounds from the sample matrix. Typically, edible oil samples are treated with a methanol KOH (e.g., 4 mol/L) solution, followed by two to three extractions with hexane or toluene [ 21 ]. Of course, KOH solution can be replaced with other alkalis, such as NaOH solution.…”

“…Of course, KOH solution can be replaced with other alkalis, such as NaOH solution. Through experiments, Wang et al [ 21 ] found that, when using 4 mol/L, 6 mol/L, and 8 mol/L KOH for saponification reactions as pre-treatments for edible oils, the recovery rates of BaP (benzo[a]pyrene) could reach 94%, 93%, and 91%, respectively. However, the alkali used in the saponification process is generally dissolved in an organic solvent like methanol [ 22 ].…”