Development of a QuEChERS-Based Method for Determination of Carcinogenic 2-Nitrofluorene and 1-Nitropyrene in Rice Grains and Vegetables: A Comparative Study with Benzo[a]pyrene

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are ubiquitous environmental pollutants attracting increasing attention because of their potent mutagenicity to humans. Previous studies of nitro-PAHs focused on investigating their formation mechanisms and detecting them in atmospheric environment; however, few studies have reported their occurrence in food samples, and regulations on nitro-PAHs are still lacking. We report in this study the development and application of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for determination of nitro-PAHs in rice and vegetable samples. Analysis of the collected samples by the validated method revealed 1-nitropyrene and 2-nitrofluorene were widespread food contaminants. A comparative study with benzo[a]pyrene, the commonly used marker for PAH exposure, showed that carcinogenic nitro-PAHs existed in rice and vegetables at similar concentrations. Dietary exposure risk, which was estimated based on the surveillance data, suggested 3.28-5.03 ng/kg/day of nitro-PAHs exposure for Hong Kong citizens from rice grains and vegetables.