Determination of Benzo[a]pyrene in Edible Oil by Nickel Oxide Deposited Silica Based Solid-Phase Extraction Combined with High Performance Liquid Chromatography-Diode Array Detector

A simple, rapid, and cost-effective method for the determination of BaP in edible oil was developed and validated. Nickel oxide deposited silica (SiO2@NiO) prepared by depositing nickel oxide onto silica using liquid phase deposition method was employed as solid-phase extraction (SPE) adsorbent for the extraction of benzo[a]pyrene (BaP) in edible oil followed by high performance liquid chromatography-diode array detector (HPLC-DAD) analysis. The edible oil was diluted with n-hexane and then directly loaded to SiO2@NiO for SPE. The n-hexane was also used to clean the fat-soluble interference in the edible oil, while BaP was selectively captured due to the electron donor-acceptor interaction with SiO2@NiO. The extraction conditions such as amount of sorbent, volume of washing solvent, type and volume of desorption solvent were optimized. The method demonstrated good linearity over the range of 6-1875 ng/g with the limit of detection of 1.3 ng/g, the spiked recoveries in the range of 97.4-105.1 %, and the relative standard deviation (RSD) less than 3.0 %. The method was applied for the analysis of BaP in 12 actual oil samples and the results showed that unrefined oil and high-temperature frying oil were at risk of BaP exceeding the acceptable level.