Abstract:Objective A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for determination of beauvercin (BEA), enniatin A (ENA), enniatin A₁ (ENA₁), enniatin B (ENB) and enniatin B₁ (ENB₁) in corn, wheat and their products was developed. Methods Samples were extracted with acetonitrile-water (85∶15, V/V), cleaned up with solid phase extraction column followed by HPLC-MS/MS determination with electrospray positive ionization (ESI+) under multiple reaction monitoring (MRM) mode, and with 2 mmol/L ammonium acetate water-acetonitrile as the mobile phase. Results The limits of detection for BEA and 4 kinds of enniatins (ENNs) ranged from 0.01 to 0.12 μg/kg for corn and corn products and 0.02 to 0.21 μg/kg for wheat and wheat products, and the limits of quantification ranged from 0.02 to 0.44 μg/kg and 0.05 to 0.68 μg/kg for both cereals. The mean recoveries ranged from 91.6% to 149.7% for corn and corn products and 100.5% to 128.2% for wheat and wheat products, respectively. The matrix induced suppression or enhancement effect ranged from 88.0% to 101.5% and 55.8% to 106.5% for both cereals, respectively. The method for BEA and ENNs determination showed good linearity and precision in all matrixes with correlation coefficient above 0.99, and the relative standard deviations were less than 15%. Conclusion The method developed was of simple operation, high sensitivity and good accuracy, which could be used for BEA and 4 kinds of ENNs determination in corn and wheat and their products.

Abstract:Objective The pulsed field gel electrophoresis (PFGE) typing method of Aeromonas was optimized from aspects of restriction enzymes and electrophoresis parameters, which reduced fragments co-migration and made them well-distributed for easily analyzing. Methods Using whole genome sequences of 6 Aeromonas, restriction fragments produced by 677 enzymes were analyzed in BioEdit software. Enzymes producing more effective fragments in appropriate number were selected, and the fitting curve and regression equation were derived from the length of restriction fragments represented as denary logarithm and the relative position of fragments in gel represented as fragments migration distance percentage of the valid length of the reference system. Digital simulation of pulsed field gel electrophoresis map was shown when length of fragments from different Aeromonas substituted into the equation. Results of digital simulation were also verified by PFGE typing assay with selected enzymes for Aeromonas typing. Isolates from diarrhea patients were subtyped by the optimized new method. Results BioEdit analysis result showed PmeⅠ, PacⅠand SwaⅠ were better than XbaⅠ as enzymes for PFGE from the aspects of total and effective number of restriction fragments. According to the result of PFGE simulation and the verification test of isolates, the distribution of fragments of PacⅠ and PmeⅠ was better distributed and less overlapped than those of XbaⅠ and SwaⅠ. Finally, PmeⅠ and PacⅠ were selected as the first and second choice of enzymes for PFGE typing, and the pulsed field conversion time was set as 2.16-63.8 s. Sixteen isolates from diarrhea patients were subtyped by new method, and the Simpson diversity index was 99.17% according to the typing result. Conclusion As enzymes used in PFGE typing, PmeⅠ and PacⅠ were better choices than XbaⅠ, and good resolution was obtained from subtyping of isolates from diarrhea. The procedure for optimizing PFGE typing method provided in this study is applicable to the establishment or optimization of other bacteria's PFGE typing method.

Abstract:Objective To understand the antimicrobial resistance of foodborne Salmonella isolates in China in 2015, and to obtain the prevalence of mcr-1 gene in colistin(CT)resistant isolates. Methods Broth microdilution method was used for antimicrobial susceptibility test of 1 070 Salmonella strains against 16 antimicrobial compounds which belonged to 10 categories, and 196 colistin resistant strains were detected for the existence of mcr-1 gene by real-time fluorescence quantitative polymerase chain reaction(PCR). Results About 71.9% (769/1 070) of the isolates showed different antimicrobial resistant levels to 16 antimicrobials, and the resistance rates to nalidixic acid(NAL), tetracycline(TET), ampicillin(AMP) and ampicillin-sulbactam(SAM) were as high as above 40%, while all strains were susceptible to carbapenems. 47.5% (508/1 070) of them were identified as multi-drug resistant (MDR) strains and were resistant to as much as nine classes of antimicrobials. There were 141 antimicrobial resistance spectrums with NAL, AMP-SAM-NAL-CT and TET as the top three spectrums. One strain of mcr-1 gene and ESBLs positive which was identified as Salmonella enterica subsp. enterica ser. London had been detected in 196 colistin resistant isolates and it was the only one strain with resistance against nice categories of antimicrobials. Serious multi-drug resistance was found in some provinces and strains recovered from raw poultry meat were detected to be the worst with resistant rate of 80.6%(349/433), followed by isolates from raw livestock meat (73.5%, 283/385). Conclusion An overall high level antimicrobial resistance was found among foodborne Salmonella isolates in China in 2015, so was the MDR condition, especially for strains recovered from some provinces and from raw poultry and livestock meat. Mcr-1 gene could be carried in foodborne Salmonella isolates recovered from China, therefore, close attention should be paid to its surveillance.

Abstract:Objective To determine the antibiotic susceptibility of isolated Salmonella spp. from import and export food and evaluate the spectrum of their multiple antimicrobial resistance,so as to provide the basis for food safety and rational clinical drug usage. Methods The Salmonella spp. of 65 isolated strains and 17 reference strains were tested for their antimicrobial susceptibility against 15 kinds of antibiotics by Kirby-Bauer method. The susceptibility was determined by the standard of Clinical and Laboratory Standards Institute (CLSI). Results All of the isolates were sensitive to cefepime, ceftriaxone, amikacin and cefotaxime. The highest drug resistance rate was for ampicillin (16.9%,11/65) and piperacillin (13.8%,9/65). Many isolates were resistant to tetracycline (13.8%,9/65), kanamycin (9.2%,6/65) and streptomycin (7.7%,5/65). Among 65 isolates,eleven strains (16.9%,11/65)were resistant to one antibiotic,one strain(1.5%,1/65) was resistant to two antibiotics, and 7(10.8%, 7/65) strains of multidrug resistance were detected which were resistant to three to six antibiotics. Conclusion Isolates of Salmonella spp. from import and export food in Beijing showed multiple drug resistance and the monitoring should be strengthened to ensure food safety.

Abstract:Objective To establish an ultra-high performance liquid chromatography tandem isotope dilution mass spectrometry method for the determination of three major allergens, such as lysozyme, egg transferrin and ovalbumin, from eggs in baked food. Methods The specific peptides of lysozyme, ovotransferrin and ovalbumin were first screened, and then the specific peptides and isotopic markers were synthesized. Samples were homogenized in a buffer solution of 200 mmol/L Tris-HCl (pH=8.0) for 2-3 times. The sample solution was mixed with trypsin in a proportion of 1∶50 (trypsin/protein ratio) and then placed on a shaking bed and hydrolyzed for 12 h at 37 ℃. The enzymatic hydrolysate was detected by the electrospray positive ion (ESI+) with multiple reaction monitoring (MRM) mode and quantified by an isotope dilution method. Results Good linear relationships within the ranges of 1-100 nmol/L with linear correlation coefficients (r²) above 0.995 was achieved for the calibration curves of nine specific peptides standards. The limits of quantitation(LOQ)of the three proteins in baked food were 0.4-10.0 μg/g. The recoveries of target proteins in baked food ranged from 65.0% to 108.5% with relative standard deviations (RSDs) less than 15.0%. Conclusion The method is sensitive, specific and accurate. It is suitable for the detection of egg allergen proteins in baked food.

Abstract:Objective To evaluate the protein microarray platform that previously established for lactoferrin detection in raw milk. Methods Triplet raw milk samples were used to implement within-run precision of 8 repeats and other triplet raw milk samples were used to implement between-run precision of 8 batches. The high concentration standard was consecutively diluted for recovery test. Three concentrations of spiked samples were used for recovery. Ten raw milk samples were detected by protein chip platform and commercial ELISA Kit, respectively. Results The within-run precision and between-run precision were 9.79%-15.90% and 11.63%-23.38%, respectively. The dilution recovery and recovery were 79.8%-129.7% and 105.7%-133.9%, respectively. The relevant coefficient of the two detection method was 0.825 2, the difference was significant (t=4.132, P<0.05), but the result of paired t test showed that there was no difference between the two method (t=1.282, P>0.05). Conclusion The protein chip platform could satisfy the requirement of laboratory test, and its operation error need to be further optimized.

Abstract:Objective To investigate the contamination of Vibrio alginolyticus in seafood sold in Beijing and compare the different identification method. Methods After enrichment with alkaline peptone water(APW), a loopful from APW culture was streaked on thiosulfate citrate bile salts sucrose agar(TCBS)and CHROMagar Vibrio simultaneously. Typical colonies of Vibrio alginolyticus were identified with reverse transcription polymerase chain reaction(RT-PCR).The isolated 95 Vibrio alginolyticus strains were also identified with VITEK 2 COMPACT GN card and rpoB gene sequencing. Results Vibrio alginolyticus strains were isolated from 116 seafood which were collected randomly from markets in Beijing. The result indicated that the detection of Vibrio alginolyticus in seafood was high in Beijing, about 82%(95/116). CHROMagar Vibrio media got higher detection rate than TCBS media, which were 82%(95/116) and 72%(83/116) respectively. RT-PCR result were in good accordance with that of rpoB gene sequencing, while VITEK 2 COMPACT GN card could only identify 32.6%(31/95) of the isolated strains as Vibrio alginolyticus. Conclusion The contamination of Vibrio alginolyticus in seafood was serious in Beijing. CHROMagar Vibrio media was better than TCBS media for isolation. RT-PCR could give a more precise result than VITEK.

Abstract:Objective This study aimed to assess the disease burden of infectious diarrhea caused by Norovirus in Shanghai, and provide evidence for the government management decision and control measures of infectious diarrhea and foodborne disease. Methods The disease burden of infectious diarrhea was assess using the data from infectious diarrhea surveillance in Shanghai and the report of Norovirus infection outbreaks in Shanghai. The indexes included disability-adjusted life years (DALYs), morbidity, treatment rate and hospitalization rates. Results The total number of infectious diarrhea cases was 4.83 million, and 1.23 million cases were caused by Norovirus, 370 cases were hospitalized. The disease burden of infectious diarrhea caused by Norovirus in Shanghai in 2014 was 2 938.98 DALYs, 0.12 DALYs per thousand. Conclusion The disease burden of infectious diarrhea caused by Norovirus in Shanghai was high, and the government should give more attention to prevention, control and management of infectious diarrhea caused by Norovirus.

Abstract:Objective To learn the status of Salmonella contamination in raw poultry sold in Henan, the serotypes and genotypes of the positive isolates were studied to provide basic data for foodborne disease traceability database in Henan. Methods Salmonella detection, serotyping and pulsed field gel electrophoresis (PFGE) molecular typing were performed by the manual for food and foodborne diseases monitoring network. Results Forty-one strains of Salmonella were detected from 165 samples and the detection rate was 24.85%(41/165). The 41 strains of Salmonella had 13 serotypes, and the dominant serotypes were Salmonella corvallis, Salmonella kentucky, Salmonella typhimurium and Salmonella dabou. Forty-one strains were divided 30 molecular patterns by Xba I digestion and pulsed field gel electrophoresis, and each pattern contained 1-5 strains with similarity ranged from 47.5%-100%. The PFGE patterns were similar in different serotypes. Conclusion The contamination of Salmonella in raw poultry was serious in Henan, the serotypes and genotypes of Salmonella were diversified, and genotypes had certain regional aggregation.

Abstract:Objective A simultaneous determination method for five benzodiazepines (nitrazepam, diazepam, oxazepam, chlordiazepoxide, clonazepam) in drinking water was developed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods Samples were concentrated and purified with MCX solid-phase extraction cartridge. The chromatographic separation was achieved using an ACQUITY BEH C₁₈ (2.1 mm×100 mm, 1.7 μm) column with methanol and water as mobile phase. The targets were analyzed with ESI operating in positive multiple reaction monitoring (MRM) mode. Quantification was performed by matrix-matched standard calibration. Results Satisfactory linearity (r²>0.999) was obtained for all targets, with the limits of quantification (LOQs) ranged in 0.050-0.500 ng/L. Average recoveries at three spiked levels were 78.2%-108.0%, with relative standard deviations (RSDs) less than or equal to 12.4% (n=6). The developed method was used to analyze 96 drinking water samples, in which 51 samples were detected containing diazepam and 13 samples containing oxazepam. The concentrations were

Abstract:Determination method of nine diarrhea shellfish poisons by ultra performance liquid chromatography-mass/mass spectrometry (UPLC-MS/MS) in bivalve molluscs was established. Methods The samples were extracted by methanol and separated on a reversed phase ACQUITY UPLC BEH C18 (2.1 mm×100 mm, 1.7 μm) column with acetonitrile-0.01% ammonium hydroxide as the mobile phase, with a flow rate at 0.2 ml/min and the column temperature of 30 ℃. The free toxins (AZA1,AZA2,AZA3,PTX2-b,OA,DTX1,DTX2,YTX and hYTX) in the samples were detected under positive and negative multiple reactions monitoring (MRM) mode through polarity switching between time segments. When any one or more toxins of OA, DTX1 or DTX2 were positive in the sample, the esterified OA, DTX1 and DTX2 were converted to the free form by alkaline hydrolysis and their hydrolyzed toxins were determined by UPLC-MS/MS and quantified by external standard method. Results The average recoveries ranged from 85.9% to 95.3% at three spiked concentrations with the relative standard deviation(RSD) of 2.76% to 4.18%. The detection limit(LOD)ranged from 4.4 to 9.9 μg/kg. The quantification limit(LOQ) ranged from 14.7 to 33.0 μg/kg. Conclusion The method was highly sensitive and simple,and was suitable for daily detection of diarrhea shellfish poisons in bivalve molluscs.

Abstract:Objective To compare the reliability of octuplet veterinary drug residue detection plate with the national standard method, and to provide the basis for the application of new products. Methods The samples of pork, beef, lamb were collected randomly from the markets in Daxing District. Samples were tested by the detection plate, for veterinary drugs residues. The positive samples were confirmed by the corresponding GB method. Results Twenty-one samples were detected veterinary drug residues among 176 samples, with the positive rate of 11.9%. Among them, 11 samples contained banned drugs, which were clenbuterol, salbutamol, chloramphenicol, pefloxacin and norfloxacin, and the remaining 10 samples had norfloxacin and sulfonamides, which were within the standard limits. Conclusion There were still some veterinary drugs in the meat on the markets.

Abstract:Objective A method was developed for simultaneous quantification of eight E vitamers (tocopherols and tocotrienols with α, β, γ and δ type) in nut matrix by hydrophilic interaction liquid chromatography (HILIC) after pretreating with accelerated solvent extraction. Methods Nut samples were extracted using accelerated solvent extraction (ASE), the separation of 8 anlaytes was achieved using BEH amide amino column (150 mm×3.0 mm, 1.7 μm) and the mobile phase was 90% hexane and 10% methyl tert-butyl ether-tetrahydrofuran-methanol (20∶0.1, V/V). Results The detection limits were ranged from 0.032 to 0.070 mg/kg with linear correlation coefficient above 0.998, while quantification limits were 0.096-0.210 mg/kg. Intraday and interday recoveries of spiking standards were 87.5%-114.2%, and relative standard deviations (RSDs) were all less than 12%. Conclusion The established method could be applied in the simultaneous detection of vitamin E isomers in nuts due to its excellent sensitivity, recovery and reproducibility.

Abstract:Objective A method was developed for the determination of 4 selenium species including selenite [Se(IV)], selenate [Se(VI)], selenocystine (SeCys₂) and selenomethionine (SeMet) in Se-enriched functional food by anion exchange liquid chromatography-hydride generation-atomic flourence spectrometry. Methods Optimisation of the chromatographic conditions led to baseline separation of the four species in 12 min was achieved on a Hamilton PRP-X100 column (250 mm×4.1 mm, 10 μm) using elution with (NH₄)₂HPO₄ 40 mmol/L at pH=6.0 as mobile phase. Results The detection limits of Se(IV)、Se(VI)、SeCys₂ and SeMet were 0.85,1.07,0.91 and 1.73 μg/L. The correlation coefficients were above 0.999 5. The recoveries were in the range of 80.2%-108.7% for all the determinations, with the RSD less than 5.0%. 0.6 mol/L hydrochloric acid was suitable for inorganic selenium with extraction efficiencies above 92%. Organic selenium required an enzymatic reaction using protease K to give satisfactory extraction efficiency above 82%. Conclusion A rapid, simple and accurate method had been developed for the determination of selenium species, and the proposed method was applied to provide technical support for monitoring the selenium species in Se-enriched food supplements.

Abstract:Objective To develop and validate the ultra high-performance liquid chromatograph coupled with mass spectrometry (UPLC-MS/MS) method for simultaneous determination of 16 mycotoxins, including aflatoxins, ochratoxins, trichothecenes, fumonisins and so on. Methods Five grams of the sample was extracted with acetonitrile/water/formic acid (79∶20∶1, V/V). After centrifuged and diluted, the extraction was separated by Cortecs C₁₈(100 mm×3.0 mm,1.6 μm) analytical column under acetonitrile-0.1% formic acid gradient eluting, then was determined by UPLC-MS/MS. Dilution isotope internal calibration was used for qualification. Results The result showed good linearities(0.05-200 ng/ml) for 16 mycotoxins in the certain correlation ranges with the coefficients all above 0.99. The limits of quantification ranged from 0.1 to 50 μg/kg. The average recoveries of 16 mycotoxins at three spiked levels ranged in 72.67%-126.92% with relative standard deviations of 0.15%-16.83%. The accuracies were acceptable by detecting natural matrix quality control samples. Conclusion The method is rapid, simple, sensitive, reproducible and accurate for simultaneous determination of multiple mycotoxins in cereals and products in routine laboratories. It meets the the requirement of mycotoxins monitoring in relative food.

Abstract:With the increasing input of national food safety supervision and the shortage of stuff, most of the food safety supervision department entrust the qualified food inspection institutions to carry out supervision sampling. The working mechanism of the food inspection institution is analyzed according to the actual practice, and the problems of supervision and inspection separation, and identity legitimacy is show. The paper finally put forward some suggestions to improve the supervision and sampling.

Abstract:Objective To understand the situation of mycotoxin residues in puerh tea from Guangzhou City, and provide reference basis for risk assessment and government supervision. Methods A total of 432 puerh tea samples were collected from wholesale markets, retail stores, super markets, catering units, online sellers and tea fair in Guangzhou City from 2013-2015. The concentrations of aflatoxin B₁, B₂, G₁, G₂ in the samples were determined by purification column high performance liquid chromatography (HPLC) with post column derivatization method. Nivalenol, deoxynivalenol and zearalenone were determined by high performance liquid chromatography-mass spectrometry (HPLC-MS). Results No aflatoxin B₁, B₂, G₁, G₂, nivalenol, deoxynivalenol and zearalenone in puerh tea samples could be detected by HPLC and HPLC-MS method. Conclusion There was no mycotoxin detected by HPLC and HPLC-MS national standard method. Puerh tea in the markets of Guangzhou City was not contaminated with mycotoxins.

Abstract:Objective To investigate the frequency of nutrition fortifier compounds in pre-packaged foods, and to provide reference for the revision of food fortifier standard and its quality standards in China. Methods Cross-sectional survey was performed between April to October in 2016, according to the food classification system of National Food Safety Standard for the Use of Food Nutritional Fortifier in Foods (GB 14880-2012). A total of 3 760 samples of pre-packaged foods were collected, special dietary foods, salt and salt products were not included. The sources of the compounds and the frequency of the compounds was statistically analyzed. Results A total of 489 fortified foods were separated from 3 760 survey samples, and the cumulative frequency of these compounds were 2 689 times. These 133 fortifier compounds in appendix B of GB 14880-2012 and its subsequent amendments, 52.6% (70/133) of them were used more than once, among which the frequency of calcium and zinc were more than 200 times. In additional, there were 47.4% (63/133) of the compounds were not used, further analysis showed that 47.6% (30/63) of them didn't have the related quality standards. The possible reasons were the cost, storage difficulties and low bioavailability, etc. Conclusion The application of nutrition compounds and its quality standard status were elucidated by this study, and it provided useful information for the revision of GB 14880-2012. For the substance without quality standards, it should be updated as soon as possible. The present compounds list should be reevaluated during GB 14880-2012 revision.

Abstract:Objective To provide constructive suggestions for the further improvement of the General Code of Practice for Food Production by analyzing the feedbacks on this standards. Methods The study was conducted by the means of questionnaire surveys in several provinces and municipalities. The data was collected through an online system and analyzed by Excel 2010. Results Most of the responders considered the standard to be reasonable. In the suggestions collected, there were 203 amendments to the content, 28 suggestions for the standard implementation, and 91 additional technical requirements proposed. These opinions mainly involved the plant environment, equipment and facilities, raw materials, etc. Conclusion The food industries had better awareness of food safety regulations but were still lack of the ability in hazard analysis and control. The promotion of national food safety standards should be strengthened, and the food industry and regulators should further enhance their ability to standards understanding and application.

Abstract:Objective In order to analyze the sulfur dioxide residue in dried aquatic products in 2015 and assess the potential risk of dietary exposure of sulfur dioxide in Chinese population. Methods The limit of sulfur dioxide in Codex was used for exposure assessment. The exposure of sulfur dioxide was compared with the acceptable daily intake (ADI) which was established by JECFA.Result It was found that 12.70% (79/622) of the samples violated the Codex limit. Furthermore, sulfur dioxide residue of dried shrimp was the most serious in which P95 value was 413.25 mg/kg and accounted for 1 377.50% of Codex limit. The dietary exposure in some major production areas, urban and Class I rural areas, as well as male and female of all age groups were higher than ADI calculated with the maximum residue. Dried shrimps were the main source of sulfur dioxide exposure compared with others. Conclusion At present, sulfur dioxide residue in dried aquatic products was common, most of which were still at the safe level. The sulfur dioxide dietary exposure of general Chinese population was below the ADI.

Abstract:Objective The aim of this study was to determine the prevalence of Listeria species in food products in Maanshan, Anhui Province. Methods From January 2009 to December 2014, a total of 2 372 food products, including meat, poultry, fishes, shrimps, animal viscera, cooked food, vegetables, flour products, bean products, eggs, juice, dairy products and ice creams, were randomly collected from restaurants, supermarkets and retail markets in Maanshan. Listeria spp. strains were isolated according to GB 4789.30-2010 method. Furthermore, all the Listeria monocytogenes were examined for the presence of virulence genes. Results Out of 2 372 tested samples, 332 (14.00%) were contaminated with Listeria spp., of which 25.15% (82/326) were isolated from meats, 23.98% (82/342) from poultry meats, 16.20% (104/642) from fishes and shrimps, 11.66% (26/223) from animal viscera, 8.49% (31/365) from cooked food, 2.88% (4/139) from vegetables, 2.20% (2/91) from flour products and 1.33% (1/75) from bean products. There was no Listeria spp. isolated in eggs, juice, dairy products and ice creams. The highest prevalence of Listeria spp. occurred in 2009 (23.97%, 70/292), followed by 2011 (15.62%, 67/429), 2012 (15.36%, 49/319), 2014 (11.65%, 48/412), 2013 (11.11%, 47/423) and 2010 (10.26%, 51/497). The difference of the prevalence rates of Listeria for different years were statistically significant (χ²=26.80, P<0.05). Six virulence genes, including hly, prfA, plcB, inlA, actA and iap, were observed in all of the L.monocytogenes isolates. Conclusion There were different contamination levels of Listeria in different food and years in Maanshan. This study revealed the potential risk of foodborne disease outbreak caused by L.monocytogenes. Persistent surveillance on the contamination of Listeria spp. in food products should be strengthened to prevent foodborne listeriosis.

Abstract:Objective To analyze the arsenic level in main food, and assess the risk of dietary inorganic arsenic exposure of residents in Guangxi. Methods Based on the concentration data of arsenic in 2010-2015 and food consumption data from Guangxi, the dietary exposure of arsenic was estimated by simple distribution model. The margin of exposure (MOE) method was adopted to assess the potential health risks of dietary inorganic arsenic exposure. Results 16 567 samples were analyzed, and the total arsenic detection rate was 42.71% (4 735/11 087), the inorganic arsenic detection rate was 48.07% (2 634/5 480). The average concentration of total arsenic in marine shellfish was the highest, followed by marine fish and mollush. The average concentration of inorganic arsenic was 0.018-0.072 mg/kg, and was the highest in rice. Rice, fresh fruits, eggs, animal offal and its products were calculated directly with the inorganic arsenic detection result. Other foods were calculated with the total arsenic detection result of which were converted to inorganic arsenic. The MOE of mean dietary inorganic arsenic exposure was above 1. However, the MOE values were less than or equal to 1 in the high consumption (P95) of the 18-34 years male group. The main sources of dietary inorganic arsenic was rice, whose contribution rate was much higher than the other food. Conclusion The level of dietary inorganic arsenic exposure in Guangxi residents is safe. However, there might be some potential health risks to the high exposure residents of the 18-34 years male group. Rice was the main food of Guangxi residents, which need further consideration.

Abstract:Objective In order to establish a method to identify chemical poisoning with an food poisoning incident as an example. Methods Sixteen organophosphorus and twelve carbamate pesticides was detected in 6 suspected samples using of 4000 QTRAP liquid chromatography-tandem mass spectrometry with EPI scan mode. Results The toxic substance carbofuran was detected in the vegetables and liver samples, and was not detected in the other four samples. No organophosphorus pesticides and other 11 carbamate pesticides were detected in all samples. Conclusion This food poisoning incident was caused by carbofuran. The establishment of a sensitive, rapid and accurate liquid chromatography-tandem mass spectrometry detection method and mass spectrometry database in the laboratory was of great significance for dealing with emergency events.