Solid Phase Extraction Combined with Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry for the Determination of 5 Trace Nitro-polycyclic Aromatic Hydrocarbons in Barbecued Foods

Background Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are the derivatives of polycyclic aromatic hydrocarbon which are direct mutagens and carcinogens to human. Nitro-PAHs can be produced in the process of food barbecuing/grilling. At present, there are few studies for the determination of nitro-PAHs in food. Objective To assess the effect of barbecued food to human health, we have established a method for the determination of 5 nitro-PAHs in barbecued foods. Methods The target nitro-PAHs were extracted with the mixture of methanol/acetone and then purified with an HLB SPE cartridge and finally analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry. Two pairs of target multiple reaction monitoring (MRM) ion pairs have been successfully identified for the target nitro-PAHs, and confirmed by high-resolution mass spectrometry to explore their formation mechanism. Results The method had linear ranges of 2.0-500 µg/L (except 1-nitronaphthalene 20-5000 µg/L) with the correlation coefficients greater than 0.995. The extraction recoveries were between 70.1% and 85.6% with the relative standard deviations less than 10.0%. The limits of detection of the method were less than 0.60 µg/L (except 1-nitronaphthalene 6.0 µg/L). Conclusions The method has been successfully applied to the analysis of 5 nitro-PAHs in barbecued foods. 1-nitronaphthalene, 1,8-dinitropyrene , 1-nitropyrene were detected in some charcoal grilled samples with the contents of 1.35-12.9 µg/kg. 1,8-Dinitropyrene was detected in some oil-fried samples with the contents of 2.12-5.12 µg/kg. Highlights This work presents an ultra-high-performance liquid chromatography-tandem mass spectrometry method for the determination of 5 nitro-PAHs in barbecued foods for the first time. The method has been successfully applied to the analysis of 5 nitro-PAHs in various barbecued foods and the nitro-PAHs were detected in some barbecued food samples. The mechanism of mass spectrometric decomposition of nitro-PAHs was investigated as well.