Determination of benzo(a)pyrene in vegetable oils was carried out using aluminium oxide for clean-up followed by reverse phase high performance liquid chromatographic (HPLC). A quantity of oil was dissolved in petroleum ether and added to an aluminium oxide column which retained the lipids. Benzo(a)pyrene in the oil was eluted from the column with petroleum ether and the collected eluate was concentrated by evaporation of the solvent. Identification and quantification was performed by HPLC using fluorescence detection at the optimized wavelength. The retention time of a benzo(a)pyrene standard was used for identification and the concentration was calculated by external calibration.
The method was tested on an oil matrix, then validated by determining the recoveries of benzo(a)pyrene from vegetable oil samples spiked with polycyclic aromatic hydrocarbons at 0.01 µg kg^-1 to 0.5 µg kg^-1. Recoveries and coefficients of variation for the oils spiked with benzo(a)pyrene standard were 90% to 102% and 1.23%-2.03% respectively. This method was then used for monitoring the level of benzo(a)pyrene in vegetable oils.