| Objectives:To establish a gc-ms method for the determination of 16 polycyclic aromatic hydrocarbons?PAHs?and 7 polychlorinated biphenyls?PCBs?in shellfish.The distribution characteristics of PCBs and PAHs in shellfish in Qingdao city were preliminarily understood,so as to provide effective data basis for the control and supervision of PAHs and PABs pollution in aquatic products and protect human life and health.Methods:1.Establishment of the detection method for PAHs and PCBs:1.1Establishment of instrumental detection method:The PAHs-PCBs standard solution use GC-MS usage,using HP-5 MS chromatographic column,set the initial temperature of 90?,20?/min up to 220?,and then to 5?/min up to 300?,keep5 min for testing,to the retention time qualitative and external standard method of peak area quantitatively.1.2The establishment of the separation and extraction method:Weighing 5.00g of the sample in the cored glass centrifuge tube,add anhydrous sodium sulfate and n-hexane-dichloromethane solution,and extract by water bath ultrasound;The supernatant was removed by centrifugation and repeated twice.The obtained extract was dissolved after spin steaming and purified by gel permeation chromatography.The purified liquid was collected and spun steaming to nearly dry.Select ion detection?SIM?mode for detection.1.3 Methodological evaluation:The linearity,correlation coefficient,accuracy,stability,peak time and reproducibility of the established method were verified,and the detection limit of the method was determined.The recovery and precision of PAHs and PCBs were calculated and methodological evaluation was carried out.2.Analysis of samples:40 samples of scallop,conch,clam,mussel,oyster and other5 categories were collected in Qingdao supermarket,wholesale market and farmers'market,with a total of 200 samples.After selecting the edible part of the homogenate,the shellfish samples were analyzed and detected according to the separation,extraction and instrumental detection methods established above.3.Dietary consumption survey:By adopting the method of 24-hour dietary review questionnaire survey and multi-stage stratified random sampling,the residents who eat shellfish products such as scallops,conches,clams,mussels and oysters were investigated by the method of 24h dietary review,consumption was collected,and consumption data were recorded by accounting method.4.Results analysis methodThe contents of PAHs and PCBs in different forms in the samples were calculated,and the chi-square test and variance analysis were performed using spss20.0 analysis software to analyze the content distribution of PAHs and PCBs in different types of shellfish.The exposure health risk index?ERI?and carcinogenic risk index?CRI?of five shellfish dietary intake PAHs and PCBs were calculated and risk assessment was conducted using the point assessment method.Results:1.Methodological evaluation of detection methods for PAHs and PCBs:With the established method of GC-MS for determination of PAHs and PCBs.The detection limit of PAHs was 0.070.27?g/kg,the correlation coefficient was 0.99820.9999,the precision was 0.73%4.82%,the recovery rate was 70.20%103.80%.The detection limit of PCBs was 0.120.34?g/kg,the correlation coefficient was 0.99800.9999,the precision was 1.10%4.30%,and the recovery rate was 75.30%103.60%.2.Detection and content of PAHs and PCBs in shellfish:Only 7 homologues of 16PAHs were detected in 5 shellfish samples collected from several major agricultural markets and supermarkets in Qingdao,and the rest of PAHs homologues were not detected;7 PCBs were detected.The contents of PAHs and PCBs in shellfish ranged from?ND?85.39?g/kg and?ND?168.66?g/kg,respectively.The maximum values of PAHs and PCBs residues were found in oysters.Among them,the detection rate of Mussel Flu was the highest?72.5%?,and the detection rate of seven PCBs homologues in scallops was the highest compared with other four kinds of shellfish,among which the detection rate of PCB52 in scallops was the highest?85.0%?,followed by oysters and mussels.The results of PCBs did not exceed the limit.A few of PAHs exceeded the limit,and most of the content values were concentrated in the middle and low levels.3.Composition characteristics of PAHs and PCBs in shellfish:Among the five shellfish samples,the content of PAHs in the middle ring?4 ring?was the highest,accounting for 64.14%of the total,while the content of PAHs in the low relative molecular weight?LMW,2-4 ring?was 91.75%to 96.31%.The overall structure proportion is 4 rings>3 rings>2 rings>56 rings.The analysis of PCBs in shellfish showed that the proportion of PCBs and HCB was relatively high,accounting for62.44%66.60%of the total PCBs;the content of trichlorobiphenyls and pentachlorobiphenyls was relatively low,and the general trend was:Hexachlorinated biphenyls>Tetrachlorobiphenyls>Pentachlorobiphenyls>Trichlorobiphenyls>Heptachloro biphenyls.4.Health risk assessment of PAHs and PCBs in shellfish:Calculate the Exposure Risk Index?ERI?of PAHs and PCBs,results show that the contact risk index in the 5kinds of PAHs and PCBs in different shellfish are less than 1,the non carcinogenic risk is small.The carcinogenic risk indices?CRI?of PAHs and PCBs in five different shellfish were calculated respectively.The total carcinogenic risk indices were obtained by adding the results,which ranged from 1.58×10-63.56×10-6and were within the acceptable carcinogenic risk range.Conclusions:1.A simple and rapid GC-MS method for determination of polycyclic aromatic hydrocarbons?PAHs?and polychlorinated biphenyls?PCBs?in seafood was established based on the national standard.The method has low detection limit,high sensitivity,simple operation,sensitivity and precision to meet the detection requirements.2.It was found that polycyclic aromatic PAHs and PCBs were detected in shellfish seafood sold in Qingdao,but most of them were low,and PCBs slightly exceeded the standard.The content and composition characteristics of PCBs and PCBs in different kinds of shellfish seafood were different.3.With the consumption situation of residents in our city,the risk assessment of residents'health is carried out to provide method and data support for the future national survey and risk assessment of PAHs and PCBs in seafood. |
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