Regioselective N-Trideuteromethylation of Tautomeric Polyaza Heterocycles.

Methods for regioselective N-trideuteromethylation of tautomeric polyaza heterocycles are highly sought-after. Disclosed herein is an N-trideuterated methylation reaction of imidazoles and pyrazoles with high regioselectivity and deuterium purity using easily available CF3SO3CD3 as the -CD3 source. This method enables the easy synthesis of important deuterium-labeled azoles, including dimetridazole-d3, ipronidazole-d3, hydroxy dimetridazole-d3, and ronidazole-d3.

Population genomics study of Vibrio alginolyticus.

Vibrio alginolyticus is a Gram-negative bacillus that causes vibriosis to human and aquatic products, including fish, shrimp and shellfish. It poses a threat to public health and causes enormous economic losses to the aquaculture industry. However, research on genetic diversity and pathogenicity-related genetic elements based on whole genome is still lacking. In this study, sixty-eight strains of V. alginolyticus were collected from four provinces of China and the whole genome sequences were obtained. Combined with 113 publicly available genome sequences downloaded from NCBI, we inferred the population structure of V. alginolyticus by using fineSTRUCTURE software, and identified the virulence and antibiotic resistance factors using the VFDB, CARD and ResFinder database. The results indicated that V. alginolyticus included two main lineages, named Lineage 1 and Lineage 2. Both lineages distributed in America and Asia, but all the European genomes were classified into Lineage 1. A single cross-ocean transmission event was inferred from one of the 12 identified clonal groups in our dataset. V. alginolyticus genome contains a variety of virulence factors, such as tlh, OmpU, and IlpA, etc. The distribution of virulence factors revealed no lineage-specificity, but some of which revealed differences in their geographical distribution. A lower frequency of VP1611, vcrD, vopD, fleR/flrC and a higher frequency of IlpA were observed in genomes of Europe than other continents. In China, a lower frequency of fleR/flrC, and no IlpA were observed in genomes from Guangxi province. Among the identified antibiotic resistance genes, TxR and fos are significantly enriched in Lineage 2. In addition, TxR is more common in genomes from Asia, compared with the American and European genomes. But in China, the frequency of TxR in Sichuan genomes is much lower than in other provinces. We also found that large fragments of plasmids or ICEs that carried multiple drug resistance genes were present in five V. alginolyticus genomes (VA24, VA28, 2014V-1011, ZJ-T and Vb1833). Based on population genomics analysis, our study delineated the population structure, distribution of virulence and antibiotic resistance related factors of V. alginolyticus, which lays a foundation for future study of genetic characters and pathogenesis mechanism of this pathogen and will improve the works on monitoring, prevention and control of this pathogen.

Assessment of dietary exposure of young Chinese children to aluminium residues.

The aim of this study was to assess the Al dietary exposure of young Chinese children aged 0-3 years via formulae, complementary foods and wheat-based foods. Al residue data were obtained from the national food contamination monitoring programme from 2013 to 2016, encompassing 13,833 samples of 12 food items with a detection rate of 76.0%. Food consumption data were gathered from the China National Food Consumption Survey conducted in 2015, comprising 20,172 children aged 0-3 years old. The mean dietary exposure to Al for the general population of young Chinese children was estimated at 0.76 mg/kg bw/week, which does not exceed the PTWI. The 97.5th percentile intakes of Al reached 3.42 mg/kg bw/week, more than 1.7 times the PTWI. Wheat-based foods contributed 80.5% of the Al intake for the general population of young Chinese children, while formulae and complementary foods accounted for 19.5% of the total intake. The dietary intake of Al from formulae and complementary foods accounted for 6.0% and 1.6% of PTWI, respectively. These findings suggested that dietary exposure to Al among the general population of young Chinese children was lower than the PTWI and that there are no health concerns related to this level of Al intake. However, more attention should be placed on the health risks associated with Al exposure from wheat-based foods for young consumers with high food consumption in China (97.5th percentile).

Risk assessment of dietary exposure to aluminium in the Chinese population.

In order to address the issue of excessive intake of aluminium (Al) from Al-containing food additives in the Chinese diet, this study conducted a dietary exposure assessment of Al in the general population based on the national surveillance data of Al content in foods and national food consumption data. It was found that the mean dietary exposure of the whole Chinese population to Al from Al-containing food additives was 1.795 mg kg‒1 bw week‒1, not exceeding the PTWI, while high dietary exposures (e.g., 97.5th percentile) to Al were 7.660 and 2.103-2.903 mg kg‒1 bw week‒1 for children, respectively, both exceeding the PTWI. It was found that the dietary exposure to Al for 32.5% of the total Chinese population and 42.6% of children aged 4-6 years exceeded the PTWI. Wheat flour and wheat-based products are the main source of dietary A l exposure (85% of the total intake); and puffed foods are the major source of Al intake for children. These findings suggested that consumption of Al-containing food additives could be a health concern for consumers with high food consumption (97.5th percentile) and children under the age of 14 years.

Dietary Exposure to Benzyl Butyl Phthalate in China.

OBJECTIVE: Benzyl butyl phthalate (BBP) is a plasticizer used in food contact materials. Dietary exposure to BBP might lead to reproduction and developmental damages to human. The present paper was aimed to assess the health risk of BBP dietary exposure in Chinese population. METHODS: The BBP contents were detected in 7409 food samples from 25 food categories by gas chromatography-mass spectrometry operated in selected ion monitoring (SIM) mode. The dietary exposures of BBP in different age and sex groups were estimated by combining the content data with food consumption data derived from 2002 China National Nutrient and Health Survey, and evaluated according to the tolerable daily intake (TDI) of BBP established by European Food safety Agency. RESULTS: It was found that BBP was undetectable in most samples and the highest level was 1.69 mg/kg detected in a vegetable oil sample. The average dietary exposure of BBP in people aged ⋝2 years was 1.03 µg/kg bw per day and the highest average exposure was found in 2-6 years old children (1.98 µg/kg bw per day). The BBP exposure in 7-12 months old children excessed 10% of tolerable daily intake (TDI) in worst scenario. . CONCLUSION: The health risk of BBP dietary exposure in Chinese population is low and, considering BBP alone, there is no safety concern.

The Survey of Cronobacter spp. (formerly Enterbacter sakazakii) in Infant and Follow-up Powdered Formula in China in 2012.

OBJECTIVE: To determine Cronobacter spp. contamination in infant and follow-up powdered formula in China. METHODS: All of 2282 samples were collected from the retail markets in China from January 2012 to December 2012, and analyzed for Cronobacter spp. by the Chinese National Food Safety Standard. Characterization of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE) with XbaI and SpeI restriction enzymes. RESULTS: Cronobacter spp. strains were isolated from 25 samples, and the positive rates in infant powdered formulas and follow-up powdered formulas were 0.90% (10/1011) and 1.18% (15/1271), respectively. Analysis of variable data regarding different purchasing store formats, seasonality, and production locations as well as comparison of infant versus follow-up formulas did not reveal statistically significant factors. During the sampling period, one of six surveillance zones did exhibit a statistically significant trend towards higher positive rate. PFGE characterization of Cronobacter spp. to elucidate genetic diversity revealed only three pairs of Cronobacter spp. out of 25 having the same PFGE patterns. CONCLUSION: The current investigation indicated a lower positive rate of Cronobacter spp. in the powdered formula in China. This evidence suggested contamination originating from multiple different sources during the manufacturing process.

Concentration of di(2-ethylhexyl) phthalate (DEHP) in foods and its dietary exposure in China.

Di(2-ethylhexyl) phthalate (DEHP) is a common plasticizer used in food contact materials that has been reported as an endocrine disruptor. In the present study, DEHP concentrations were analyzed in foods in order to determine dietary exposure among the Chinese population, including the general population (aged 2-100) and four age group, that is children aged 2-6, adolescent aged 7-12, young people aged 13-17 and adults aged 18 years old and above. 1704 food samples were collected during 2011-2012 and categorized into 12 food groups which covered major foods in China. Food consumption data were taken from China National Nutrient and Health Survey which was performed in 2002 and includes data from 68,959 subjects. Mean concentrations of DEHP were combined with individual food consumption data to estimate dietary exposure. It was found that DEHP levels in foods ranged from not detected to 3.41 mg/kg, with highest mean values in meat (0.23 mg/kg) and vegetable oils (0.21 mg/kg). Mean dietary intakes of DEHP in the general population, children, and adults were 2.34, 4.51, 2.03 µg/kg bw per day, respectively. The 97.5% intakes in these populations were 5.22, 8.43, 3.64 µg/kg bw per day, respectively. The main food sources of DEHP dietary intake were cereals (39.44%), drinking water (16.94%) and meat (15.81%) in children, and cereals (44.57%), meat (15.70%) and drinking water (12.28%) for adults. These findings suggested that dietary exposure to DEHP among Chinese population was lower than tolerable daily intake of DEHP and there are no health concerns based on generally accepted exposure limits.

[Development of a model diets for consumers with high exposure to food chemicals].

OBJECTIVE: To develop and verify a model diet for consumers with high exposure to food chemicals. METHODS: Based on the assumption that a person might consume average amounts of several different foods but only two or three at high levels, a model diet were put forward to calculate the high exposures to certain food chemical.Important parameters of this model were selected by comparing the outputs of this model with those of a reference model-semi-probabilistic model that is based on individual data. The concentration data of lead, cadmium and mercury (45 832, 43 862 and 25 243 samples respectively) from the national risk surveillance for chemical contaminations and harmful factors (2011), and the consumption data from the national survey on nutrition and health status in Chinese population (2002) were used in this model optimization process. The final model was verified using concentration data of eight chemical contaminations from national surveillance database of 2010. RESULTS: When 90, 95 and 97.5 percentile exposure being calculated under the conditions that 7, 12, 20 and 30 food categories was used respectively, the model containing two high consumption foods (2+x model) got results lower than the reference values (the relative deviation < 0) , the model containing three high consumption foods (3+x model) got results higher than the reference values (the relative deviation > 0 ),but the relative deviation of the two models were both within 20%. The verification results showed that the dietary exposure results of 8 food contaminations got from 3+x model were all higher than and(or) close to those got from semi-probabilistic model, and the relative deviations were between -5% and 25%. CONCLUSION: The 3+x model diet can fulfill the demands of "conservative" and "accurate" on exposure assessment model, and can give reliable estimations of high exposure to food chemicals occurred in various food categories.

[The determination of phthalic acid esters in edible vegetable oils by gas chromatography-mass spectrometry].

OBJECTIVE: We aimed to establish a quantified method for the 17 phthalate acid esters (PAE) in edible vegetable oil by gas chromatography-mass spectrometry (GC-MS) with the pretreatment of acetonitrile extraction and silica/N-(n-propyl)ethylenediamine (silica/PSA) mixed solid phase extraction column and evaluated the PAE of 25 edible oil samples from supermarkets in Hangzhou city. METHODS: The internal standard solution (D4-DEHP) was added in edible vegetable oil sample. The analytes were extracted by acetonitrile with 1 min vortex, and centrifuged at 3050×g for 5 min. The supernatant was then cleaned with silica/PSA column, and eluted with acetonitrile. The elution was dried with N2 flow at 50°C and diluted to 1.0 ml with hexane. Then, 17 PAE were tested by GC-MS and quantified with internal standards. The repeatability and sensitivity of the assay were evaluated. PAE were then determined in 25 plastic buckets of edible vegetable oil from supermarkets in Hangzhou city. RESULTS: By the quantification of internal standard of D4-DEHP, a good linearity range of related 17 PAE was observed. The correlation coefficient was 0.994-1.000 and the standard lowest quantified level was 0.05-0.15 µg/ml. The spiking recoveries of 17 PAE were 78.3%-108.9% with the RSD of 4.3%-12.1% (n=6). The method detection limits were 0.1-0.2 mg/kg. In 25 plastic buckets of edible vegetable oil from Hangzhou, DMP, DEP, DIBP, DBP and DEHP were detected at the range of <0.1-1.8 mg/kg and the detection rates were 12% (3/25), 24% (6/25), 100% (25/25), 96% (24/25) and 100% (25/25), respectively. Other 12 PAE was not detected. For DBP with the level of <0.1 to 1.3 mg/kg, the results of 16% (4/25) samples exceeded the regular migrating limit of 0.3 mg/kg. For DEHP of <0.2-1.8 mg/kg, the data of 12% (3/25) samples were beyond the regular migrating limit of 1.5 mg/kg. CONCLUSION: The pretreatment by silica/PSA mixed solid phase extraction column can satisfy the PAE determination requirements in edible vegetable oils. The DMP, DIBP, DEP, DBP and DEHP were detected from the survey of 25 edible oil samples in Hangzhou city.

A survey of 16 rare Earth elements in the major foods in China.

OBJECTIVE: The aim of this survey was to investigate the level of contamination of the most consumed foods in China with 16 rare earth elements (REEs), and to provide the basic data for establishing and revising food safety standards for REEs. METHODS: Sixteen REEs in foods were measured by inductively coupled plasma-mass spectrometry (ICP-MS) in the labs of the Centers for Disease Control and Prevention of four provinces and two municipalities, during 2009-2010. RESULTS: 1 231 samples were analyzed and 19 121 concentration data of 16 REEs were collected. The REEs levels in the investigated foods varied significantly. The concentrations of cerium (Ce), dysprosium (Dy), yttrium (Y), lanthanum (La), and neodymium (Nd) were relatively high, while the remaining eleven REEs were at low levels. The mean values of total rare earth element oxides (REOs) in cereals, fresh vegetables, fresh aquatic products, fresh meats and eggs varied from 0.052 mg/kg to 0.337 mg/kg. CONCLUSION: 16 REEs in the major foods were at very low contamination levels in the investigated regions.

[Survey and analysis of ethyl carbamate in commercial fermented foods in Hangzhou in 2010].

OBJECTIVE: To observe the ethyl carbamate concentrations in different commercial fermented foods in Hangzhou in 2010. METHODS: In 2010, 237 commercial fermented food samples of eight categories, including yellow wine, white spirit, wine, beer, cooking wine, sauce, vinegar and fermented bean curd, were purchased from 3 different size markets respectively in Hangzhou. The ethyl carbamate was measured by gas chromatography-mass spectrometry in selection ion mode, after the samples were coupled with D5-ethyl carbamate, and purified by diatomite solid phase extraction column. RESULTS: The results showed that ethyl carbamate was detected in all samples analyzed (100%) with the range from 2.0 µg/kg to 515.0 µg/kg. The ethyl carbamate average (median) levels in 8 food categories were descending with fermented red bean curd (182.2 µg/kg (161.2 µg/kg)), yellow wine (159.6 µg/kg (121.0 µg/kg)), cooking wine (86.8 µg/kg (95.6 µg/kg)), white spirit (72.0 µg/kg (60.5 µg/kg)), soy sauce (47.2 µg/kg (40.7µg/kg)), vinegar (26.7 µg/kg (31.8 µg/kg)), wine (15.7 µg/kg (16.8 µg/kg)) and beer (2.2 µg/kg (2.3 µg/kg)). CONCLUSION: The ethyl carbamate was detected in all fermented foods in Hangzhou in 2010, and the levels of ethyl carbamate in red bean curd and yellow wine were higher than others.

Study on migration of melamine from food packaging materials on markets.

OBJECTIVES: To study the migration of melamine into foods from plastic food packaging materials and dairy product containers commonly used in China. METHODS: 37 samples were collected from the market. The EU migration testing conditions were adopted with distilled water, 3% acetic acid, n-hexane and 15% ethanol being chosen as the simulating solutions. The HPLC method was used to detect melamine. RESULTS: No melamine was detected in 15 dairy product containers. Among the 22 plastic samples, 16 of polypropylene, and polycarbonate types had no detectable amount melamine while a low level of melamine was found in 3 of the 6 melamine resin containers. CONCLUSION: Migration of melamine from food packaging materials in China market is in line with the requirements of EU.

Simultaneous determination of nonnutritive sweeteners in foods by HPLC/ESI-MS.

Nonnutritive sweeteners are the low calorie substances used to replace sugar and other caloric ones. Determination of these sweeteners in foods is important to ensure consistency in product quality. In this study, seven artificial (aspartame, saccharin, acesulfame-K, neotame, sucralose, cyclamate, and alitame) and one natural sweetener (stevioside) were simultaneously determined in different foods using high performance liquid chromatography (HPLC) coupled with electrospray ionization mass spectrometric detection (ESI-MS). The target compounds were quantified using a selective ionization recording (SIR) at m/z 178, 397, 377, 293, 641, 312, 162, and 182 to cyclamate, sucralose, neotame, aspartame, stevioside, alitame, acesulfame-K, and saccharin, respectively, with warfarin sodium (SIR m/z 307) being used as an internal standard. The correlation coefficient of the calibration curve was better than 0.998 (n = 6), in the range of 0.05 to 5.00 microg/mL for cyclamate, 0.30 to 30.0 microg/mL for sucralose, 0.10 to 10.0 microg/mL for neotame, 0.20 to 20.0 microg/mL for aspartame, 0.50 to 15.0 microg/mL for stevioside, 0.08 to 8.00 microg/mL for alitame, 0.10 to 15.0 microg/mL for acesulfame-K, and 0.05 to 5.00 microg/mL for saccharin. The limits of detection (LODs) were below 0.10 microg/mL, whereas the limits of quantification (LOQs) were below 0.30 microg/mL. It is concluded that the method has merits such as high sensitivity, specificity, and simplicity versus the those of the other methods reported in the literature.

[A new method for safety monitoring of natural dietary supplements--quality profile].

OBJECTIVE: A new method for safety monitoring of natural dietary supplements--quality profile was proposed. It would convert passive monitoring of synthetic drug to active, and guarantee the security of natural dietary supplements. Preliminary research on quality profile was completed by high performance liquid chromatography (HPLC) and mass spectrometry (MS). METHODS: HPLC was employed to analyze chemical constituent profiles of natural dietary supplements. The separation was completed on C18 column with acetonitrile and water (0.05% H3PO4) as mobile phase, the detection wavelength was 223 nm. Based on HPLC, stability of quality profile had been studied, and abnormal compounds in quality profile had been analyzed after addition of phenolphthalein, sibutramine, rosiglitazone, glibenclamide and gliclazide. And by MS, detector worked with ESI +, capillary voltage: 3.5 kV, cone voltage: 30 V, extractor voltage: 4 V, RF lens voltage: 0.5 V, source temperature: 105 degrees C, desolvation temperature: 300 degrees C, desolvation gas flow rate: 260 L/h, cone gas flow rate: 50 L/h, full scan mass spectra: m/z 100-600. Abnormal compound in quality profile had been analyzed after addition of N-mono-desmethyl sibutramine. RESULTS: Quality profile based on HPLC had good stability (Similarity > 0.877). Addition of phenolphthalein, sibutramine, rosiglitazone, glibenclamide and gliclazide in natural dietary supplements could be reflected by HPLC, and addition of N-mono-desmethyl sibutramine in natural dietary supplements could be reflected by MS. CONCLUSION: Quality profile might monitor adulteration of natural dietary supplements, and prevent addition of synthetic drug after "approval".

[National continuous monitoring on the content of lead in preserved eggs from 2000 to 2006].

OBJECTIVE: To investigate the pollution level and development trend of lead in the preserved egg in our country. METHODS: By the national food contamination monitoring system and under the strict analysis quality control, the content of lead in the preserved eggs was analyzed according to the national standard method (GB/T 5009.12-2003) in fourteen provinces from 2000 to 2006. RESULTS: All 1358 data on contents of lead in the preserved eggs were obtained during seven years, the total average was 1.782 mg/kg, the maximum was 334.0 mg/kg, P90 was 3.50 mg/kg, P95 was 7.397 mg/kg and P97.5 was 12.01 mg/kg, all exceeded 2 mg/kg of the national limit standard, and the rate of violated samples exceeded 10.0%. Analyzing from time, contents of lead in the preserved eggs were depressive from 2.994 mg/kg to 1.138 mg/kg year after year. CONCLUSION: The lead contamination in preserved eggs was serious in whole country. It shows that the continuous work of monitoring and forewarning should be carried out to make the contamination of lead in preserved eggs to reduce year by year.