[Determination of beauvercin and enniatins in rice flour and wheat flour by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a method for the determination of beauvercin(BEA), enniatin A(ENNA), enniatin A1(ENNA1), enniatin B(ENNB) and enniatin B1(ENNB1) in rice flour and wheat flour by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). METHODS: Samples were extracted by acetonitrile-water, purified by Oasis Prime HLB solid-phase extraction column. The sample solution was separated by waters BEH C_(18) column(2.1 mm×100 mm, 1.8 µm). The detection was performed in the electrospray positive ionization(ESI+) under multiple reaction monitoring(MRM) mode. The internal standard method and the matrix-matched calibrations were used for quantification. RESULTS: The linear relationships of BEA and 4 kinds of enniatins(ENNs) were good in the range of 0.1-50.0 ng/mL(r>0.999). The average recoveries of BEA and ENNs in rice flour and wheat flour were 96.4%-105.4% and 99.1%-109.2%, with the relative standard deviations(RSD) of 1.01%-7.42% and 1.09%-9.69%(n=6). The detection limits(LOD) of BEA and ENNs were 0.03 µg/kg. The quantitative limits(LOQ) of BEA and ENNs were 0.1µg/kg. The matrix induced suppression or enhancement effect were 72.7%-99.3% and 60.8%-100.4%, respectively. The levels of emerging BEA and ENNs in wheat flour were higher than rice flour. The detection rate of enniatin B was highest in wheat flour and rice flour, the contents were 0.03-9.57 µg/kg and 0.03-0.56 µg/kg, the positive percentage were 98.5% and 36.4%. CONCLUSION: The method is quick, easy, accurate and sensitive, which is suitable for the determination of BEA and 4 kinds of ENNs in rice flour and wheat flour.

[Nutritional composition in different processed wheats from Shaanxi Province].

OBJECTIVE: To study the content of nutritive ingredients of 11 kinds of different processed wheats planted in Shaanxi Province, and assess their nutritional value. METHODS: The macronutrients, moisture, ash and vitamins in 11 different wheat were determined. The index of nutritional quality(INQ) method was used to evaluate the different nutrients in 11 kinds of wheat and the fuzzy membership function method was used to evaluate the nutritional value comprehensively. RESULTS: The contents of water and carbohydrate in 11 kinds of whole wheat flour were lower than those of special flour and wheat core flour. The contents of ash, fat, protein and total dietary fiber were significantly higher than those of special flour and wheat core flour. The wheat flour contained high levels of vitamin B_1, certain vitamin B_2 and trace amount of ß-carotene. Under the parameters selected in this article, the comprehensive evaluation shows that Jinmai 54 had the highest nutritive value among 11 kinds of wheat, while Zhoumai 26 had the lowest nutritive value. CONCLUSION: 11 kinds of wheat is rich in protein, vitamins and other nutrients, peeling can cause a large loss of vitamin B and vitamin E in wheat flour. The comprehensive nutritional value of whole wheat flour is higher than the special flour and wheat core powder.

[Simultaneous determination of 25-hydroxyvitamin D and vitamin K_1 in serum by ultra-performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a method for analysis of 25-hydroxylvitamin D_2(25(OH)D_2), 25-hydroxylvitamin D_3(25(OH)D_3)and vitamin K_1 in serum by ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS), which can be applied in diagnosis of vitamin deficiency and estimation on the nutritional status of people. METHODS: Serum samples mixed with d_6-25(OH)D_3, d_7-vitamin K_1(internal standard)were precipitated with acetonitrile and extracted with n-hexane. The sample solution was separated using BEH C_(18) column(2. 1 mm×100 mm, 1. 7 µm) with gradient elution using methanol-water containing 0. 1% formic acid as mobile phase. The target molecule was detected in positive electrospray ionization(ESI~+) and multiple reaction monitoring. RESULTS: The concentration of 25(OH)D_2, 25(OH)D_3 and vitamin K_1 showed good linearity in the range 5. 0-75. 0 ng/mL, 2. 0-81. 5 ng/mL and 0. 3-12. 0 ng/mL, respectively, with the correlation coefficients greater than 0. 995. The limits of detection(LOD) of 25(OH)D_2, 25(OH)D_3 and vitamin K_1 were 1, 0. 25 and 0. 1 ng/mL, and the limits of quantification(LOQ) for 25(OH)D_2, 25(OH)D_3 and vitamin K_1were 3, 0. 75 and 0. 3 ng/mL, respectively. The recoveries of three levels in the matrix were 98. 5%-104. 3%, the relative standard deviation(RSD) were all less than 5. 0%(n=6). CONCLUSION: An UPLC-MS/MS method for analysis of 25(OH)D_2, 25(OH)D_3 and vitamin K_1 in serum is sensitive, rapid, accurate and suitable for the nutritional surveillance of vitamin D and K_1 in the population.

Rhodamine B in spices determined by a sensitive UPLC-MS/MS method.

Rhodamine B (RhB) is a banned food additive and has been classified as illegal colourant. Therefore, the risk of RhB contamination should be strictly monitored. In this study, a sensitive UPLC-MS/MS method was applied to monitor RhB in 292 various spices such as chilli, pepper and tomato products. The results showed 22.7% of chilli powder samples, 18.5% of pepper powder samples, 11.1% of chilli oil samples and 9.1% of pepper oil samples were contaminated with RhB. Chilli powder contained RhB up to 44,935 µg/kg with an average of 743 µg/kg, pepper powder up to 65.9 µg/kg with an average of 4.1 µg/kg, chilli oil up to 14.6 µg/kg with an average of 1.0 µg/kg and pepper oil up to 1.1 µg/kg with an average of 0.2 µg/kg, respectively. Considering the common consumption of chilli products and pepper products by so many consumers, RhB exposure is significant and should be decreased.

[Analysis on contamination of zearalenone and dietary exposure assessment in food samples of Shaanxi Province in 2013-2016].

OBJECTIVE: To investigate the contamination of zearalenone in food in Shaanxi Province, and to assess the dietary zearalenone exposure and the health risk of intaking zearalenone from corn products for Shaanxi residents. METHODS: In 2013-2016, samples of five kinds of food including grains, vegetable oil, liquor and infants' food were collected randomly from ten cities, and determined with ultra-performance liquid chromatography. Dietary intake assessment of human exposure to zearalenone was carried out in combination of food consumption data with concentration of zearalenone. RESULTS: 1193 samples were detected zearalenone and the total detection rate was 17. 27%, with the mean value of 13. 5 µg/kg. Among all food samples, oil products were more seriously polluted than other kinds of foods, its detection rate was 79. 37%. And 12 samples of grain products exceed the standard, the exceeding standard rate was 1. 64%, which were all corn products. The level of zearalenone detected in wheat flour, rice, millet, beer and bakery products was low. CONCLUSION: The overall level of zearalenone contamination inmarket food is common, but corn products may be the severely contaminated foods with zearalenone in Shaanxi Province. The risk assessmentresult suggests that the current dietary intake of zearalenone from corn products in Shaanxi Province has no appreciable effect on health, however, the concentrations of zearalenone in corn products are relatively high, and need to be monitored in the future.

Determination of nitrofurans metabolites residues in aquatic products by ultra-performance liquid chromatography-tandem mass spectrometry.

A method was described for monitoring four nitrofuran metabolites including 5-methylmorpholino-3-amino-2-oxazolidinone (AMOZ), 3-amino-2-oxazolidone (AOZ), 1-amino-hydantoin (AHD) and semicarbazide (SEM) in aquatic products. The analytes were quantified by ultra-performance liquid chromatography-tandem mass spectrometry operating in positive ion multiple monitoring mode (MRM) after 2-nitrobenzaldehyde derivatization. The matrix calibration curve was established with correlation coefficient (R(2)>0.99) in the range of 1-100 ng ml(-1). Limit of detection and limit of quantification for all analytes were 0.5 and 1.5 µg kg(-1), respectively. Recovery rates and relative standard deviations ranged from 88% to 112% and 2% to 4%, respectively. The validated method was successfully applied to detect nitrofuran metabolites in 120 fish samples. The analytes were detected in 6/16 species of fish samples, with a total detection rate of 6.5%. AOZ was most frequently detected (8.3%), followed by AMOZ (7.5%), AHD (5.0%) and SEM (5.0%). The method is proposed for monitoring nitrofuran metabolites in aquatic products.

[Analysis on contamination of aflatoxins in food samples in Shaanxi Province from 2012-2015].

OBJECTIVE: To investigate the contamination of aflatoxins in food in Shaanxi Province, and provide the basic data of dietary intakes of aflatoxins for food safety assessment. METHODS: In year 2012- 2015, 1007 food samples of eight kinds of food including grains, beans, vegetable oil, nuts and seeds, condiment, liquor, tea and infants' food were collected randomly from ten cities, and determined with UPLC. RESULTS: 1007 samples were detected aflatoxins and the total detection rate was 10. 7%. The detection range was 0. 070- 323 µg / kg, with the mean value of 2. 34 µg / kg. Among all food samples, only peanut products were more seriously polluted than other kinds of foods. CONCLUSION: The overall level of aflatoxins contamination in market food is low, but peanut products might be the contaminated foods with aflatoxins in Shaanxi Province, and should be given more attention.

[Investigation on contamination situation of malachite green in freshwater fish and its dietary exposure assessment of Shaanxi Province].

OBJECTIVE: To investigate the residue levels of malachite green (MG) in freshwater fish and assess the dietary MG exposure of Shaanxi residents. The second aim was to assess the health risk of intaking MG from freshwater fish for Shaanxi residents. METHODS: The samples were determined by UPLC-MS/MS after purified by neutral alumina SPE cartridges and separated by waters-BEH C18 column (2.1 mm x 100 mm, 2.5 µm). The MOE method was used to assess the risk of intaking MG from freshwater fish for Shaanxi residents. RESULTS: The average detection rate of MG in freshwater fish in Shaanxi province was 7.32% and the highest residue level was 428 µg/kg. The detection rate was quite different in different fish species. The catfish devoted the highest detection rate which was 28.57%. In ten cities of Shaanxi, the highest detection rate was obtained from Yulin which was 33.33%. CONCLUSION: The health risk of intaking MG from freshwater fish is quite low for Shaanxi residents, however the contamination of illegal use of MG in freshwater fish was severe in Shaanxi Province. Supervision and inspection of MG should be strengthened in fish farming.