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A gas chromatography-tandem mass spectrometry based method has been developed for multi-determination of 18 polychlorinated biphenyls (including 7 indicator PCBs, and 12 coplanar PCBs) in the meat, head, shell and egg of Macrobrachium nipponense. 20 g homogenized samples are extracted by the mixture solution of V (dichloromethane) : V (hexane) = (1 : 1). Then concentrated sulfuric acid is used for the digestion of organic matter. Thereafter, the extracts are cleaned up through SPE florisil column and make it ready for analysis. GC-MS/MS technique was used for the analysis. In terms of the GC part, column HP-5 (30 m × 0.32 mm, 0.32 μm) is used for the separation of 18 PCBs through temperature programming. For the tandem mass spectrometry condition, multiple reaction monitoring (MRM) model with positive electron impact ion source (EI+) is chosen for the qualification and quantification. The results reveal that in the spiked levels of 50, 400 and 1 000 ng/kg, the average recoveries ranged from 72% to 109% for all the 18 PCBs in each part of M. nipponense. The relative standard deviations is below 10%, the limits of detection of this method is 0.10-10 ng/kg. This method has good precision and accuracy. The pretreatment method is simple and fast. Thus this method can be used in the determination of the above mentioned 18 PCBs in M. nipponense. Testing of the actual samples from a farm in Nanjing, only some PCBs is checked out. [ABSTRACT FROM AUTHOR]

Fate of carbendazim residue during the beer brewing process was determined by the high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The simultaneous determination of carbendazim in different samples (barley, malt, spent grain, agreement wort, finalize wort and beer) were developed. For barley, malt and spent grain samples, the QuEChERS method was used for the pretreatment. 6 g MgSO4 and 1.5 g NaAc were used for the extraction, and 150 mg of MgSO4, 50 mg C18 and 50 mg PSA were used for the purification. Agreement wort, finalize wort and beer samples were directly diluted with deionized water and then purified with C18 solid phase extraction column. The main results are presented as followed: The mean recoveries varied from 72% to 99% and the relative standard deviations (RSD) was less than 9%. The limit of quantitation was 0.01 mg/kg. The residues of carbendazim is 1.99 mg/kg in barley, 2.71 mg/kg in malt, 0.41 mg/kg in spent grain, 1.37 mg/kg in agreement wort, 1.34 mg/kg in finalize wort and 0.12 mg/kg in beer. During saccharification, boiling and fermentation processes, the residue of carbendazim has been reduced with the processing factor 0.51, 0.98 and 0.089, respectively. The removal efficiency of fermentation was the highest. [ABSTRACT FROM AUTHOR]

In the study, presence, distribution of 18 polychlorinated biphenyls (PCBs), including 7 indicator PCBs, 12 dioxin-like PCBs (DL-PCBs), and 4 heavy metals (Pb, As, Cd, Hg) have been investigated in Ictalurus punctatus, sediment and water from Jiangsu fish farms; thereafter, risk assessment have been conducted for the ecological risk and human health. The results showed that PCB28, PCB52, PCB114 were the most frequently found pollutants in all collected fish, sediment and water samples. Upon to the different geographical location of fishery farms across Jiangsu Province, components of PCBs presented differently, which implied different pollution sources. The concentration of PCBs found in sediment (178.4-457.2 pg/g) was higher than that detected in water (0.2-11.9 ng/L). Higher concentrations of PCBs was also found in fish meat (1.28-267.96 pg/g), compared to that in fish liver (0.64-95.46 pg/g), and guts and stomach (1.20-45.94 pg/g). Higher content of fat in fish meat could be the possibility of higher enrichment of PCBs compared to the other tissues. Meanwhile, higher concentration of heavy metal was found in sediment than that in water. The total enrichment of heavy metal in fish was found to be Pb﹥As﹥Cd﹥Hg in descend order. Total amount of heavy metals enriched in different tissues were found to be liver ﹥gastrointestinal system﹥meat. All the DL-PCBs TEQ (1.9 pg/g) is less than the maximum residue limit (MRL) of EU (6.5 pg/g). THQ (US, EPA) and R model were employed for the risk assessment by comprising the estimated daily intake and the daily allowed intake. The results revealed that the carcinogenic risk of 18 kinds PCBs and 4 kinds heavy metals remained acceptable level in this study. [ABSTRACT FROM AUTHOR]