| Polychlorinated biphenyls(PCBs)are a class of persistent organic pollutants,which is widely present in water environment and can finally cause damage to the human body through enrichment of aquatic organism and amplifiication of food chain.At present,the monitoring and testing of 19 kinds of PCBs(including 7 kinds of indicative PCBs and 12 kinds of risk-monitoring PC Bs)in aquatic products by the inspection organizations in China is mainly based on the method of GB 5009.190-2004,using gas chromatography-mass spectroscopy(GC-MS).However,this method is flawed by complex process,high consumption of reagents,mass ive experimental materials and long time of sample treatment.Thus,in order to monitor and control the pollution of PC Bs in aquatic products,it has important practical significance to establish a quick and easy method for routine batch testing and determination of PC Bs.This research firstly explored and optimized conditions of sample pretreatment with greatly shortened time and simplified procedure to finally established a method of simultaneously determining 19 kinds of polychlorinated biphenyls in aquatic products by gas chromatography-quadrupole time-of-flight mass spectroscopy.To investigate the potential safety hazard of PCBs-related pollution in aquatic products in Guangzhou.The newly developed method was further used to carry out residue detectio n of PCBs in aquatic products by random inspection.Whether the 7 kinds of indicative PCBs in commercially available aquatic products meet the requirement of national safety index was also examined.In additon,the effect of the toxic equivalent,contact risk index and carcinogenic risk index of 19 kinds of PC Bs on human health were assessed.The results of this research can provide a certain scientific data,detection and assessment methods for the risk monitoring of PC Bs pollution in the commercially available aquatic products in Guangzhou.The specific contents and results of the research are mainly as follows:1.To optimize and explore a method of fastly determining 19 kinds of PCBs in aquatic products,a fast,simple and convenient method of sample pretreatment was explored by the use of dispersed high-speed homogenization technique with mixed solution of acetone and petroleum ether as extraction solvent,the extracting solution doubly purified by concentrated sulfuric acid and chromatographic column,e luted by n-hexane.It is easy to operate withless consumption of experimental materials and simplified procedure so that the pretreatment extraction of PC Bs in samples was completed within 2 hours,in comparison with 3 days by the national standard method.The explored method is suitable for the rapid extraction and purification of 19 kinds of PCBs in aquatic products for daily batch sample preteatment.2.A method of simultaneously determining 19 kinds of polychlorinated biphenyls in aquatic products by gas chromatography-quadrupole time-of-flight mass spectroscopy has been established.The above mentioned extracting solution was separated by GC capillary column with helium as a carrier gas at the flow rate of 1.5 m L/min.The resultant separation was ionized by electron impact ion source.The data were collected by TOF/MS full scan mode.The qualitative analysis was performed using retention time and ion precise mass number,and the quantitative analysis was performed using external standard method.The result revealed that,19 kinds of PCBs have a good linearity within t he range of 5.0 ?g/L~500.0 ?g/L with the correlation coefficient of more than 0.9986,the limits of detection(LOD,S/N=3)between 0.12 ?g/kg and 1.07 ?g/kg and the limits of quantification(LOQ,S/N=10)between 0.40 ?g/kg and 3.57 ?g/kg.At 3 different standard addition levels of 5.0 ?g/kg?10.0 ?g/kg and 20.0 ?g/kg,the average recoveries of 19 kinds of PCBs is between 79.6% and 103.4%,and the intra-day relative standard deviation is between 2.2%~9.6%;at 3 different standard addition levels of 20.0 ?g/kg?100.0 ?g/kg and 200.0 ?g/kg,the average recoveries of 19 kinds of PCBs is between 77.4% and 104.6% and the inter-day relative standard deviation is between 2.7% and 9.8%.It is indicated that,the developed method is accurate,sensitive and reliable and suitable for the monitoring and detection of 19 kinds of PCBs in aquatic products.3.The developed analytic detection method was used to detect the commercially available aquatic products in Guangzhou,and the risk of PC Bs pollution of them was asses.60 different representative aquatic products including fishs,shrimps,shellfish,crabs were purchased and detected with the abovementioned method.The result revealed that the total detectable amount of 19 kinds of PCBs in commercially available aquatic products was between 4.45 and 90.80 ?g/kg and the average was 27.43 ?g/kg;the total detectable amount of 7 kinds of indicative PCBs was between 0 and 34.92 ?g/kg and the average was 12.43 ?g/kg.The total detectable amount of 19 kinds of PCBs in commercially available fish was between 4.45 and 77.68 ?g/kg and the average was 24.53 ?g/kg;the total detectable amount of 7 kinds of indicative PCBs in commercially available fish was between 0 and 28.42 ?g/kg and the average was 10.46 ?g/kg.The total detectable amount of 19 kinds of PCBs in commercially available shrimps was between 5.85 and 34.97 ?g/kg and the average was 17.77 ?g/kg;the total detectable amount of 7 kinds of indicative PCBs in commercially available shrimps was between 2.86 and 23.27 ?g/kg and the average was 9.45 ?g/kg.The total detectable amount of 19 kinds of PC Bs in commercially available shellfish was between 9.09 and 90.80 ?g/kg and the average was 35.80 ?g/kg;the total detectable amount of 7 kinds of indicative PCBs in commercially available shellfish was between 4.63 and 34.92 ?g/kg and the average was 17.03 ?g/kg.The total detectable amount of 19 kinds of PCBs in commercially available crabs was between 33.01 and 59.70 ?g/kg and the average was 44.50 ?g/kg;the total detectable amount of 7 kinds of indicative PCBs in commercially available crabs was between 9.67 and 36.50 ?g/kg and the average was 19.04 ?g/kg.The results show that the detectable amount of 7 kinds of indicative PCBs in commercially available aquatic products was far less than the national standard.The pollution level of PCBs in all kinds of aquatic products in descending order as crabs > shellfish > fish > shrimps.The mean of toxic equivalent of pollution of 19 kinds of PCBs was 1.02×10-1 pg TEQ/g,the mean of contact risk index was 1.6×10-2 and the mean of carcinogenic risk index was 1.6×10-5,all of which are acceptable to human body,suggesting that the commercially available aquatic products in Guangzhou are in a good quality. |
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