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ObjectiveTo understand the relative bioavailability （RBA） of cadmium in different aquatic products. Based on the consideration of the gender differences and the relative bioavailability of cadmium in different foods， the physiologically based toxicokinetic （PBTK） model of cadmium was further optimized and verified. The correlation between internal and external exposure in quantitative risk assessment of food safety was optimized， and the provisional tolerable daily intake （PTDI） value of cadmium was derived. MethodsThe relative bioavailability of cadmium in different aquatic products was determined in four-week-old Balb/c female mice. The PBTK model of cadmium metabolism was optimized by ABC-MCMC method using combined internal and external exposure data of cadmium in Shanghai residents， and the PTDI was calculated accordingly. ResultsExcept for scallops and squid， the RBA of aquatic samples was less than 1， indicating that the absorption rate of cadmium in aquatic products was lower than that of cadmium chloride. The higher RBA of squid and scallop may be due to the presence of cadmium in the visceral organs， which is conducive to cadmium absorption and its higher concentration of cadmium. Frying at the temperature less than 160 ℃ reduced cadmium absorption but may increase cadmium absorption at the temperature greater than 160 ℃. The optimized model parameters converged well and the model could reasonably estimate urinary cadmium level according to the external exposure of cadmium. The PTDI value was0.466 4 μg·（kg·day）-1 according to the optimized single-chamber model. ConclusionThe relative bioavailability of cadmium in different foods varies greatly， except for squid and scallops， RBA is less than 1， and cooking processing will affect the RBA of food. The construction of the PBTK model did not only consider the effects of gender differences on cadmium metabolism， but also included the relative bioavailability data to optimize and adjust the correlation coefficient of absorption rate. Compared with the model without RBA adjustment， the adjusted model has enhanced the ability to predict urinary cadmium level， which provides a new， more accurate method for the risk assessment of food safety.
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Objective@#To optimize the pretreatment method of N-nitrosamine compounds in ready-to-eat aquatic products. @*Methods@#Market-sold ready-to-eat aquatic products were collected, homogenized and distilled by steam. The samples were extracted for 10 minutes using dispersive liquid-liquid microextraction (DLLME) with ethanol, trichloromethane and sodium chloride (3.0 g). After centrifugation, the organic phase in the lower layer was collected and subjected to gas chromatography-tandem mass spectrometry (GC-MS/MS). The six common N-nitrosamine compounds were determined in ready-to-eat aquatic products using multiple reaction monitoring mode (MRM) and quantified by the internal standard method. @*Results@#The optimized method exhibited a good linear relationship at concentrations of 10.0 to 500 μg/L for determination of 6 N-nitrosamine compounds (correlation coefficient of greater than 0.999), with 0.05 to 0.60 μg/kg limit of detection, 0.15 to 1.60 μg/kg limit of quantitation, mean spiked recovery rates of 71.8% to 108.9%, and relative standard deviations of 1.4% to 8.6%. N-Nitrosodimethylamine showed the highest detection rate in 20 market-sold ready-to-eat aquatic products (90%), and the detection rates of N-Nitrosopyrrolidine, N-Nitrosodiethylamine and N-dibutylnitrosamine were 15%, 10% and 10%, respectively. @*Conclusion@#Steam distillation combined with DLLME may optimize the pretreatment method of N-nitrosamine compounds in ready-to-eat aquatic products and meet the measurement requirements.
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Objective To evaluate the risk of disease of Vibrio parahaemolyticus in aquatic products of raw food animals for population in guangzhou,and determine risk management points. Methods VP quantitative detection was carried out in aquatic products of raw food animals sold in Guangzhou from 2009 to 2022.sQMRA was applied to assess Vibrio parahaemolyticus risk of aquatic products of raw food animals. According to stratified analysis based on the pollution of Vibrio parahaemolyticus and evaluation results,carry out risk management and analysis. Results Among the 98 samples were detected positive of VP from 1 343 samples from 2009 to 2022 , with an overall positive rate of 7.30%.The number of Vibrio parahaemolyticus infection cases caused by eating aquatic products of raw food animals in Guangzhou was 3012. If the proportion of raw food is reduced , the number of Vibrio parahaemolyticus infection cases will be significantly reduced. The number of cases caused by eating raw fash will be reduced from 2128 to 217.The detection rate of Vibrio parahaemolyticus in raw fresh water products was much higher than that in marine products. The probability of infection in the population was higher. The number of cases caused by eating raw fash was the highest.The detection rate of Vibrio parahaemolyticus was higher in raw crustaceans and molluscs. The incidence of Vibrio parahaemolyticus infection cases caused by eating raw fash in the four quarters varied from high to low as such sequence ,4.93×10-5 in the three quarters , 2.53×10-5 in the second quarter , 2.40×10-5 in the first quarter ,1.77×10-5 in the fourth quarter . Conclusion The risk of disease of Vibrio parahaemolyticus in aquatic products of raw food animals was higher. The public health education should be done well. Aquatic products should be cooked thoroughly before eating . Reduce the intake of raw aquatic products and avoid cross contamination. Focus on the risks of summer and autumn seasons and seafood such as crustaceans and molluscs. Concentrate on scientific research on Vibrio parahaemolyticus pollution of fresh water products.
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ObjectiveIn order to ensure the food safety of cultured aquatic products in China， strengthen the supervision and improve detection efficiency， a high-throughput screening method for drug residues in aquatic products by mass spectrometry is to be developed. MethodsLiquid chromatography-electrostatic field track well high resolution mass spectrometry and C18 column were used to separate and collect the information of ion fragments and retention time of 195 veterinary drug standards in positive ion mode， and drug residues in aquatic products were extracted by organic solvents. ResultsThe mass spectrum database and detection methods of 195 veterinary drug standards were established， and a pre-treatment method was developed for extracting veterinary drug residues from aquatic products by acetonitrile and ethyl acetate. The detection method was sensitive， accurate， simple and rapid， and the adding standard recovery of more than 80% compounds reached 70%‒110%. ConclusionThe establishment of this method can quickly and massively screen drug residues in aquatic products， provide technical support for food safety risk monitoring and supervision， cope with the increasing demand for aquatic products and aquaculture volume year by year， and provide a theoretical basis for the subsequent development of mass spectrometry high-throughput detection methods.
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ObjectiveThe study aimed to evaluate the measurement uncertainty in the determination of five cacaine anesthetics and their metabolites residues by high-performance liquid chromatography-tandem mass spectrometry （LC-MS/MS）. MethodsThrough the establishment of mathematical model， the sources of uncertainty were analyzed， and various components were quantified and synthesized to evaluate the influence of the uncertainty components on the measurement results． ResultsThe uncertainties of the experiments were mainly derived from calibration curve fitting， sample pretreatment， recovery rate， standard solution preparation and measurement repeatability. Furthermore， the expanded uncertainty related to the content in shrimp （k=2） was 1.18 μg‧kg-1 at 8.68 μg‧kg-1 for tricaine methanesulfonate （MS-222）， 1.28 μg‧kg-1 at 9.11 μg‧kg-1 for benzocaine， 13.5 μg‧kg-1 at 91.4 μg‧kg-1 for 4-aminobenzoic acid， 12.2 μg‧kg-1 at 91.0 μg‧kg-1 for p-acetylamino benzoic acid， and 11.3 μg‧kg-1 at 95.3 μg‧kg-1 for 3-aminobenzoic acid， respectively. ConclusionThis method is suitable for the uncertainty analysis of cacaine anesthetics and their metabolites determination in aquatic products by LC-MS/MS， and can provide scientific and reliable basis for the measurement accuracy.
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An ultra-high performance liquid chromatography-mass spectrometry ( UPLC-MS/MS) method was developed for the determination of 8 kinds of cephalosporins, cefoperazone, cefquinome, cefalonium, cefazolin, cefapirin, Ceftiofur, cefpirome and cefalexin, in edible parts of aquatic products. The samples were extracted with acetonitrile-water and cleaned up by multi-walled carbon nanotubes ( MwCNTs) SPE cartridge. All the target compounds were separated on an Acquity Xselect CSH C18 column with gradient elution by using acetonitrile and 0. 1% formic acid aqueous as eluent, and detected by UPLC-MS/MS under ESI+ ionization and MRM mode. Under optimized conditions, this method had a good linearity (R2≥0. 995) and the limits of quantification were in the range of 2-10 μg/kg ( S/N=10 ) . The recoveries of the method for the target compounds spiked at three different levels were 67. 3%-94. 2% with the relative standard deviations (RSDs) of 3. 3%-14%. The method had the characteristics of low cost, high accuracy and good precision, and could meet the requirements of cephalosporins determination.
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Objective To investigate the content of cadmium in shellfish in Guangdong Province and make dietary exposure assessment of cadmium in shellfish.Methods The shellfish samples were collected from Pearl River Delta,Eastern and Western Guangdong Province using random sampling method.Point assessment method was used to evaluate the exposure of dietary cadmium intake from shellfish.The risk of dietary cadmium exposure from shellfish were evaluated.Results Three hundred and seven samples were included in the analysis.The median concentration of cadmium in shellfish was 0.630 mg/kg and the exceeding standard rate was 23.8％ (73/307).The exceeding standard rates in Eastern Guangdong,Western Guangdong and Pearl River Delta were 19.4％ (13/67),23.5％ (16/68),and 25.6％ (44/172),respectively.The corresponding median concentration of cadmium were 0.530,0.806 and 0.853 mg/kg,and the difference was not statistically significant (x2 =0.94,P ＞ 0.05).The average (P50) and high level (P97.5) daily intake of cadmium from shellfish by the total survey population was 0.957 μg/d,and 4.511 μg/d,respectively.The monthly intake of cadmium associated with shellfish calculated from average and P97.5 exposure doses accounted for 1.91％ and 9.02％ of PTMI,respectively.Conclusion The cadmium content of some shellfish in Guangdong Province exceeded the standard.However,the cadmium intake from shellfish by the survey population was not high.