ABSTRACT
Polycyclic aromatic hydrocarbons (PAHs) represent a category of persistent organic pollutants that pose a global concern in the realm of food safety due to their recognized carcinogenic properties in humans. Food can be contaminated with PAHs that are present in water, air, or soil, or during food processing and cooking. The wide and varied sources of PAHs contribute to their persistent contamination of food, leading to their accumulation within these products. As a result, monitoring of the levels of PAHs in food is necessary to guarantee the safety of food products as well as the public health. This review paper attempts to give its readers an overview of the impact of PAHs on crops, their occurrence and sources, and the methodologies employed for the sample preparation and detection of PAHs in food. In addition, possible directions for future research are proposed. The objective is to provide references for the monitoring, prevention, and in-depth exploration of PAHs in food.
ABSTRACT
A simple, rapid, and reliable method based on dispersive solid-phase extraction (d-SPE) and gas chromatography-mass spectrometry (GC-MS) was developed for quantitating polychlorinated biphenyls (PCBs) in vegetable samples. Parameters affecting both the extraction yields and cleanup efficiency, including the type and volume of extraction solvent, extraction time, type and volume of cleanup sorbent, and cleanup time, were optimized. Matrix effects were evaluated, and matrix-matched calibration was recommended. Under the optimized conditions, carboxylated multiwalled carbon nanotubes (MWCNTs-COOH), which exhibit excellent adsorption capabilities due to large surface area and unique structure, were employed as d-SPE sorbent to remove interfering substances, rather than the analytes, from vegetable samples. Satisfactory linear relationship was observed for all PCBs across a concentration range of 5-500 µg/kg with correlation coefficients no less than 0.9993. Four representative vegetables (cucumber, tomato, lettuce, and cabbage) were selected as matrices for method validation. Each matrix was spiked at concentrations of 5, 10, and 100 µg/kg to evaluate recoveries, which ranged from 84.5% to 116.5% with relative standard deviations (n=6) between 0.6% and 17.6%. The limits of detection and the limits of quantification ranged from 0.3 to 1.4 µg/kg and 0.8 to 4.5 µg/kg, respectively. Twelve real vegetable samples were analyzed using the proposed method. Three of the target PCBs were detected in one lettuce sample with the total concentration of 17.9 µg/kg.
ABSTRACT
A method for the rapid determination of 18 polychlorinated biphenyls (PCBs) in tea by gas chromatography-mass spectrometry (GC-MS) coupled with dispersive solid-phase extraction (dSPE) was developed and evaluated. Carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and primary secondary amine (PSA) were used as sorbents in pretreatment process. PCBs were ultrasonically extracted from tea samples with hexane-acetone (1:1, v/v), and purified with the mixed sorbents of MWCNTs-COOH and PSA after replacing hexane-acetone by toluene. The PCBs were determined by an electron impact ionization source and selected ion monitoring mode. The analytes were qualitatively confirmed from the retention time and relative abundance ratio of characteristic ions, and quantified by a matrix-matched standard solution. The chromatographic and MS parameters influencing separation and sensitivity were optimized, and major factors affecting the extraction and cleanup efficiency including type and volume of extraction solvent, extraction time, type and amount of cleanup sorbent, and clean-up time were investigated. The performance of the method was evaluated. Under optimum conditions, satisfactory linear relationship was observed with the content of PCBs ranging from 5 to 500 µg/kg, with correlation coefficients (r) no less than 0.9998. The 18 PCBs in three kinds of tea matrices including Biluochun tea, Tieguanyin tea and Pu'er tea were spiked at 5, 10 and 100 µg/kg to evaluate recoveries, which ranged from 90.7% to 115.2% with relative standard deviations (n=5) between 0.3% and 10.9%. The limits of detection and the limits of quantification were 0.3-1.7 µg/kg and 5 µg/kg for each PCB, respectively. The method is simple, rapid, accurate, sensitive and effective, and is suitable for the determination of the 18 PCBs in different kinds of tea.
