Abstract:Objective To explore the effect of lanthanum nitrate on immunity in rats. Methods One hundred and sixty SPF weaned rats were randomly divided into two batches, 80 rats in each group and randomly divided into control, low, medium and high dose group, with 20 rats (male and female) in each group.On the 24th day after birth, lanthanum nitrate solution was administered at doses of 0,2, 20 and 60 mg/kg BW respectively. On the 51st day after birth, the first batch of rats were tested for main organs, organ-body ratio, peripheral blood lymphocyte type and serum cytokines; splenic T and B lymphocyte proliferation and splenic antibody-producing cells were measured on the 54th day after birth to the second batch of rats. Results There was no significant difference of body weight among the three dose groups and the control group to the two batch of rats (P>0.05). The absolute and relative weight of kidney and viscera of male rats in middle and high dose groups were significantly higher than those in control group (P<0.05). The brain weight and viscera ratio of female rats in low dose group were higher than those in control group (P<0.05). The number of natural killer cells in the high dose group was significantly lower than that in the control group, with dose-response relationship (P<0.05).The ratio of CD4/CD8 in the low dose group was significantly higher (P<0.05). The number of T cells in the low dose group was significantly higher(P<0.05), however the number of B cells in the low dose group was significantly lower(P<0.05). Based on the immunotoxicity test parameter. Conclusion In this experiment, lanthanum nitrate had immunotoxic effects on rats, based on the immunotoxicity test parameter, the baseline lower limit value of immunotoxicity was 8.10 mg/kg BW.

Abstract:Objective To investigate molecular characteristic and drug resistance patterns of Cronobacter isolated from retail infant foods. Methods Fifty strains of Cronobacter isolated from infant foods between 2010-2016 were typed by pulsed field gel electrophoresis(PFGE)after their chromosomal DNA were digested with restriction endonucleases Xba I, and the PFGE patterns were analyzed by BioNumerics software. Antibiotic susceptibility test was carried out by micro-broth dilution method to analyze drug resistance patterns. Results Fifty Cronobacter strains revealed 47 PFGE patterns with similarity ranged from 28.7% to 100.0%. Isolates from different regions or different enterprises were distributed among clusters with highly polymorphic, and without regional aggregates and specificity. But four strains isolated from different batches of two enterprises belong to the same clone. All strains were sensitive to nalidixic acid, ciprofloxacin, cefepime, amikacin, cefotaxime and ceftriaxone. The strains were resistant to sulfadiazine, ampicillin, chloramphenicol, sulfamethoxazole-trimethoprim, amoxicillin-clavulanic acid, kanamycin and gentamicin at different degrees. And 7 strains were multi-drug resistant.Conclusion It should be paid more attention to the contamination of Cronobacter in the infant foods, because some enterprises may be contaminated with sustained Cronobacter and some multiple antibiotic resistant strains appeared in the study.

Abstract:Objective To investigate the matrix effects of 5 alkaloids such as papaverine and morphine in 3 different food matrices by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry. Methods The matrix effect was analyzed before and after the extraction of the blank solution spiked with different concentration of the standard solution. The matrix effect of the determination of the 5 alkaloids was evaluated by fitting the standard curve and comparing the slope and intercept. Results The matrix effect of solid and semisolid matrix were strong, and narcotine, thebaine and codeine were easily influenced by the matrix effect. The effect of matrix effect could be effectively reduced or eliminated by optimizing the gradient elution program, adding internal standard solution and dilution samples. Conclusion The matrix effect was closely related to the type of sample matrix and the structure of compound. The improved method of matrix effect in this study could provide reference for the determination of poppy husk alkaloids in different sample matrix.

Abstract:Objective An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with pass-through solid phase extraction method was developed to determine 7 non-selective cyclooxygenase inhibitors in fish. Methods Samples were extracted with extractant containing 90% acetonitrile and 5% formic acid, and then purified with Oasis PRiME HLB columns. The analysis was performed with Waters CORTECS UPLC C₁₈(100 mm×2.1 mm,1.6 μm)column. The mobile phase was consisted of 0.1% formic acid aqueous solution and acetonitrile containing 0.1% formic acid by gradient elution, and multiple reaction monitoring(MRM)mode with electrospray ionization was used to analyse salicylic acid, piroxicam, naproxen, indomethacin, diclofenac sodium, ibuprofen and phenylbutazone. The effect of the dosages of extractant, formic acid and acetonitrile in cleaning-up agent was studied. The main influence factors and analytical conditions were modified. Results Seven linear calibration curves were obtained with correlation coefficients (r²) ≥0.995 2. The recoveries at three concentrations ranged from 80.3%-95.5%. The limits of quantifications were from 2 to 10 μg/kg. Conclusion The method has the advantages of simple pretreatment, high recovery and good reproducibility which is suitable for the determination of 7 non-selective cyclooxygenase inhibitors in fish.

Abstract:Objective To establish a method for the simultaneous determination of eight volatile halogenated hydrocarbons in drinking water by headspace-gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods 10 ml of water sample was accurately transferred to a 20 ml headspace vial and 1.0 g NaCl was added, the mixture was equilibrated at 55 ℃ for 30 min, then analyzed by GC-MS/MS. The samples were separated by capillary column HP-5MS(30 m×0.25 mm,0.25 μm)and determined by multi-reaction monitoring (MRM) mode. The quantitative ion peak area was used for quantification, retention time and abundance ratio of characteristic ion pairs was used for qualitative analysis. Results The linear correlation coefficients (r) were from 0.999 0 to 0.999 7, the relative standard deviation (RSD) were from 1.6% to 5.2%, the spiked recoveries were in the range of 85.0%-98.0% (n=6), and the detection limits were between 0.005 1-0.064 μg/L. Conclusion This method was rapid, simple, precise and sensitive. It was suitable for the accurate detection of 8 volatile halogenated hydrocarbons in drinking water.

Abstract:Objective To establish a method for the determination of 24 phthalate esters(PAEs)in drinking water by gas chromatorgraphy-triple quadrupole mass spectrometry. Methods PAEs in drinking water were absorbed by C18 glass solid phase extraction(SPE)column and eluted with 6 ml ethyl acetate, rotary evaporated to dry and dissolved in 1 ml N-hexane. The volumn of injection was 1 μl. The sample was separated on a HP-5MS capillary column (30 m×0.25 mm,0.25 μm), and the identification and quantification were performed by gas chromatorgraphy-triple quadrupole mass spectrometry in multiple reaction monitoring (MRM) mode. The external standard method was used for quantification. Results Twenty-four compounds had a good linear relationship (r>0.995).The limits of detection(LODs) were 0.014-0.50 μg/L and the limits of quantification(LOQs) were 0.047-1.7 μg/L. The recoveries at three spiked levels were between 80.2%-113.7%, and the relative standard deviation were between 2.7%-10.3%(n=6). Ten different water samples and nine PAEs were detected by this method. Conclusion This method was accurate, precisive and rapid and it was suitable for simultaneous detection of 24 PAEs in drinking water, source water and bottled water.

Abstract:Objective A gas chromatography-flame photometric detector (sulfur filter) [GC-FPD(S)] method for the residues determination of ferbam, propineb and maneb in fruit and vegetable samples was established. The method could improve the specificities of detection for dithiocarbamates. Methods By alkaline buffer with strong chelating agents, insoluble heavy metal salts were converted into water-soluble sodium salts. With ion pair methylation, dithiocarbamates could be converted into esters which could be used for GC-FPD(S). Methodological verification was carried out based on optimized sample pretreatment and chromatographic conditions. Results The square of dithiocarbamates concentration exhibited a good linear relationship in certain range. The detection limits of fenbam, propineb and maneb were 0.1,0.5, and 0.5 mg/kg respectively. Furthermore, the average recoveries were 75.3%-94.6%, and the maximum relative standard deviations was 14.1%. Conclusion This method was simple, accurate and reliable for residues detemination of dithiocarbamates pesticides in fruit and vegetable samples. All indexes meet the requirements of pesticide residue detection.

Abstract:Objective A ultra performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) was developed for the simultaneous determination of 2,4,5-trichlorophenol, 2,4,5-trichlorophenoxyacetic acid and pentachlorophenol in edible lard. Methods The edible lard samples were extracted by 80% acetonitrile, then puried with solid phase extraction(SPE)and exane, and loaded on a Atlantis T3 column (2.1 mm×150 mm,3 μm). Acetonitrile-5.0 mmol/L ammonium acetate solution was used as the mobile phase for gradient elution.The compounds were detected by UPLC-MS/MS with negative electrospray ion source (ESI-) under multiple reaction monitoring mode. The matrix-matched external standard method was used for quantitation. Results 2,4,5-trichlorophenol, 2,4,5-trichlorophenoxyacetic acid and pentachlorophenol had an excellent linear relationship in the range of 2.0-100.0 μg/L with correlation coefficient (r) above 0.999. The limits of detection were 0.09,1.59 and 0.90 μg/kg, and the quantification limits were 0.29,5.28 and 3.00 μg/kg. The recoveries of the three compounds ranged from 71.9%-109.5% with relative standard deviation of 0.2%-9.2% (n=6). Conclusion The method was simple,sensitive and accurate, and was suitable for high-throughput detection for 2,4,5-trichlorophenol, 2,4,5-trichlorophenoxyacetic acid and pentachlorophenol in edible lard.

Abstract:Objective A method was established for simultaneous determination of nine N-nitrosamines in cooked meat using enhance matrix removal QuEChERS-gas chromatography-tandem mass spectrometry(GC-MS/MS).Methods The samples were extracted by enhance matrix removal QuEChERS.The analytes were separated on a HP-INNOWax quartz capillary column(30 m×0.25 mm,0.25 μm), and ionized by electron impact ion source(EI).The data were collected by multiple reaction monitoring(MRM) mode,followed by qualitative screening and quantitative analysis. Results Nine N-nitrosamines had good linearities in the range of 0.20-50.00 μg/kg, with correlation coefficients above 0.997. The detection limits of were 0.02-0.1 μg/kg. The average recoveries of the nine N-nitrosamines were 78%-120% with relative standard deviations of 3.42%-15.24%.Conclusion The QuEChERS purification combined with GC-MS/MS method was rapid, accurate and sensitive,and suitable for the determination of nine N-nitrosamines in cooked meat.

Abstract:Objective This thesis aims at establishing the measure method of aflatoxin in cereals with supercritical fluid extraction-supercritical fluid chromatography-mass spectrometer/mass spectrometer (SFE-SFC-MS/MS) method. Methods Samples were extracted by supercritical CO₂-methanol(98∶2,V/V). The analysis was carried out on an Shim-pack UC-X RP C₁₈ column (150 mm×4.6 mm, 3 μm) with isocratic elution using a mobile phase of supercritical CO₂ and methanol. Mass spectrometry acquisition was done in the positive ion mode and the analytes were detected in the multiple reaction monitoring (MRM) mode. Results The correlation coefficients of aflatoxin B₁, B₂, G₁ and G₂ were above 0.998 in the range of 0.5-20 ng. The method had good linear relation. The recovery rate in samples of rice and corn grit were 92.3%-107.9%,93.0%-106.1%,93.4%-104.9%,92.8%-102.2% respectively, relative standard deviations of 3.0%-4.3%, 3.2%-4.5%, 3.0%-4.6%, 3.0%-4.5%(n=6) respectively. The limit of quantitation was 0.1 μg/kg. Conclusion This method was quick, simple, safe and accurate. It was available for measuring the amount of aflatoxin B₁, B₂, G₁, G₂ in cereals.

Abstract:Objective To analyze the connotation of the third-party platform liability system for online food transactions, discuss the existing problems of the system, and provide reasonable suggestions for improving the third-party platform liability system for online food transactions. Methods The obligations and responsibilities of the third party platform were clarified by the relevant legal provisions. The importance of fulfilling the obligations of third-party platforms is illustrated by case analysis. Combining with practice, this paper explores the problems existing in the third-party platform of online food transaction. Results There are some problems in the liability system of the third-party platform of online food transaction, such as unclear legal provisions, ineffective information sharing, lack of internal motivation to implement the review obligation, and unclear responsibility boundaries. Conclusion There are still many problems in the responsibility system of the third-party platform of online food. It is necessary to perfect laws and regulations, build prevention system and reward reporting system, establish information sharing system, and establish responsibility sharing and co-governance mechanism.

Abstract:Objective To investigate the contamination of Arcobacter in retail chicken meat in Shijiazhuang City,and provide basic data support for the distribution characteristics and prevention and control of Arcobacter in Shijiazhuang. Methods A total of 90 chicken meat samples were randomly collected from wholesale markets, supermarkets and butchers in Shijiazhuang. Enhanced membrane filter technique was used to isolate Arcobacter from the chicken meat samples, multiplex polymerase chain reaction(PCR)detection was used to identify Arcobacter and 16S rRNA and rpoB genes of the Arcobacter isolates were sequenced and analyzed to confirm the detection result. Results Among the 90 samples, 60 samples were Arcobacrer positive(66.67%),and 86 Arcobacter strains were isolated. Forty-nine of the eighty-six isolates were A.cryaerophilus and the rests were A.butzleri. Among the 60 Arcobacter positive samples, 45 samples (75.00%) were A.cryaerophilus positive and 35 samples (58.33%) were A.butzleri positive. About 22.22%(20/90) samples were cocontaminated with A.cryaerophilus and A.butzleri. There were significant differences in the contamination rate of Arcobacter in different markets. Conclusion In Shijiazhuang City, the contamination of Arcobacter in retail chicken meat was serious, and the contamination rate of A.cryaerophilus was higher than A. butzleri in chicken meat samples. The contamination rate of A.cryaerophilus and A.butzleri were high.

Abstract:Objective To establish the exposure assessment parameters for food contact materials (FCMs) in beverage packaging in China. Methods Using beverage consumption survey data in 9 provinces and cities of China in 2013, food consumption factor (CF) and food-type distribution factor (fT) were derived through calculation of consumption of beverage based on FCMs type and food type. Results The average beverage intake of Chinese consumer was 1 243.34 g per day. The CF of plastics, glass, coated metal, polymer coated paper and board were 0.28,0.24,0.23 and 0.21, respectively. For beverage in contact with plastics, the food types were mainly acidic and aqueous, with fT of 0.96 and 0.04, respectively. Uncoated metal was used for dry food packages, such as tea. Beverage in contact with uncoated paper and board were mainly aqueous and acidic, and their fT were 0.67 and 0.26, respectively. Conclusion The consumption factor and food-type distribution factor obtained in this work could be applicable to the exposure assessment of food contact material used in beverage packaging of China.

Abstract:Objective To analyze the cadmium level of main food and to assess the safety of dietary exposure of cadmium. Methods A total of 875 samples of 11 categories of food were collected from Xiacheng District. Cadmium contents in food were determined and then the cadmium intake and margins of safety (MOS) were calculated among Xiacheng residents and a risk assessment was conducted. Results Cadmium was detected in 695 of 875 samples(79.43%). 55 out of 796 samples with cadmium content above national standards(6.91%)The highest cadmium content among 11 categories of food was seaweed (4.510 0 mg/kg). The cadmium exposure of Xiacheng residents from main food categories were 15.785 8 μg/kg BW, which was below the provisional tolerable monthly intake (25 μg/kg BW), and the MOS was above 1, so the health risk of dietary exposure was low. The highest contributions were from aquaculture (43.97%), edible mushroom (17.42%), and rice (16.48%). Although consumption of aquaculture and edible mushroom was very low, the contribution was high due to the serious cadmium contamination. Aquaculture and edible mushroom were identified as high risk food for cadmium exposure. Conclusion The level of dietary cadmium exposure from the main food was safe in general. However, more attention should be paid to the high risk food of aquaculture and edible mushroom.

Abstract:Objective In order to provide references for the revision of the standard, feedbacks and problems from regulatory authorities, inspection agencies, industries, relevant experts were collected and analyzed during the implementation of the national food safety standard for pathogenic microorganism limits (GB 29921-2013). Methods The feedback opinions were collected through the national food safety standard evaluation and feedback platform. Content analysis were applied and the data were analyzed by Microsoft Office Excel. Results From January 1st, 2016 to December 31th, 2017,7 opinions were collected, with 745 effective opinions mainly concerning the standard scope (42%,313/745), food classification (34%,252/745), specific pathogen limits (9%,68/745), sampling plans (3%,23/745) and relations with other standards (3%, 21/745), etc. The main opinions included further clarifying the scope of standards and the relationship with other standards, improving food classification and related description, and review of specific pathogens or limits. ConclusionIt is imperative to further revise and integrate the national food safety standard for pathogenic microorganism limits (GB 29921-2013). At the same time, the publicity and implementation of national food safety standards should be continuingly strengthened, so that the understandings and operations of regulators, inspection agencies and enterprises on the risk management of microbial hazards could be more effective.

Abstract:Objective To analyze the epidemic factors of an outbreak of Norovirus infectious diarrhea in a middle school in Hubei Province, so as to provide a basis for prevention and control measures. Methods The case was investigated by field epidemiology, and the outbreak data and various factors were analyzed by descriptive epidemiology and case control. Results The outbreak involved 91 of suspected cases and 2 cases of latent infection, with an incidence of 33.8%(91/269). Of the four chefs, two were silent infection. The first case was from class 8-2 at 7∶30 on February 15th. 69.2% (63/91) of the cases occurred from 8∶00 to 24∶00 on February 15th, with median of 16∶00. The result of the case-control study suggested an increased risk of eating breakfast on February 14th [odds ratio (OR)=9.93,5% confidence interval(95%CI):1.17-84.04]. Conclusion This event was an outbreak of infectious diarrhea caused by Norovirus. In the peak season of Norovirus infection, the monitoring of infectious diarrhea in collective units and schools should be strengthened, and health education should be actively carried out, so as to effectively prevent the outbreak of infectious diarrhea caused by Norovirus.

Abstract:Objective This study aimed to get a better understanding of epidemiological characteristics of mushroom poisoning events in Anhui Province to provide reference to map out intervention strategies. Methods The descriptive analysis was conducted on the data of mushroom poisoning events and cases in Anhui Province reported through “Foodborne Disease Event Reporting System” and “Foodborne Disease Surveillance Reporting System” from 2016 to 2017. Results A total of 129 mushroom poisoning events were included with 223 poisoning cases and 2 deaths in Anhui Province from 2016 to 2017.The mushroom poisoning events mainly occurred during August to October, in the rural areas and home sittings, and were high in border region between Wanbei and Wanzhong, and Wannan mountain region. The most of patients were older than 40, and the common clinical findings were gastrointestinal symptoms, the correct rates of first visit were 69.23%(90/130). Conclusion Mushroom poisoning events in Anhui Province showed high risk season and area, effective intervention measures should be taken to key population and district in order to reduce mushroom poisoning events.