Objective: In this paper, a method of gas chromatography mass spectrometry for determination of free resveratrol in grape wine was established. Methods: After evaporated to eliminate ethanol, sample of grape wine was extracted with ethyl acetate, and evaporated again to dryness. The residues were derivatized with N,O bis (trimethylsianyl) trifluoroacetamide plus 1% trimethychlorosilane. Then, qualitative and quantitative analysis of cis and trans resveratrol were carried out using GC MS scan mode. Results: The average recoveries were 85.6%-110.5%,and the relative standard deviations were 8.2%-11.5%, when resveratrol was added to grape wine at 0.25-1.25 mg/L levels. The correlation coefficient was 0.995 in range of 0.50-10.00 mg/L. The detection limit for resveratrol in grape wine was 0.005 mg/L. Further 15 grape wines made in China were analyzed. The contents of cis resveratrol were 0.02 -0.56 mg/L and trans resveratrol were 0.15-1.28 mg/L. Total resveratrol were 0.26-1.48 mg/L. Conclusion: This assay is accurate and reproducible for determination of free resveratrol in grape wines.

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.

Objective: To establish a method for the determination of furans in tea by headspace-gas chromatographic mass spectrometry. Methods: The 20% sodium chloride solution and isotope internal standards were added to the crushed and weighed tea sample. Furan, 2-methylfuran, 3-methylfuran, 2,5-dimethylfuran were separated by HP-PLOT Q capillary column and then determined by gas chromatography mass spectrometry with electron impact ionization mode. Results: In the range of 5-400 ng, good linear relationships were observed in the four furan compounds, with the correlation coefficients ranging from 0.999 2 to 0.999 6. The detection limits ranged from 0.2 to 1.9 μg/kg, the quantification limit ranged from 0.4 to 3.1 μg/kg. The recovery rates of furans ranged from 95.4% to 128.2% when spiked at 5.0, 20.0 and 100.0 μg/kg, and the relative standard deviations ranged from 0.8% to 11.3%. Eighty-one tea samples were determined, the concentration of four furan compounds was highest in black tea, followed by dark tea, oolong tea, green tea and scented tea. Conclusion Headspace-gas chromatography-mass spectrometry can reduce the matrix interference of tea, and meet the requirements in the linear range, recovery and precision, which is suitable for simultaneous determination of four furan compounds in tea.

A sequential clean-up method was developed for the quantification of 10 plant growth regulators in bean sprout by the gas chromatography / mass spectrometry (GC / MS). The analytes were firstly extracted by the acided acetonitrile. Extraction was concentrated and re-dissovled by methanol. Then, it was divided to two aliquots. One of that was analyzed for 2,4-D-butyl ester and 2,4-D-ethyl ester after the purification by QuECHERS cartridge. Another one was treated by MCS solid phase extraction column including diverse eluting steps. After eluting by 5 mL methanol, composition 1 was obtain, concentrated, and methyl esterified by 10% boron trifluoride methanol solution. The treated extract was used for the determination of 4-chlorophenoxy acetic acid, β-naphthyl acetic acid, 2,4-dichlorophenoxy acetic acid, indole acetic acid and indole butyric acid. Composition 2 collected by eluting with 5 mL 5% amonium methanol was used for the determination of paclobutrazol, Kinetin, 6-Benzylaminopurine. The clean-up procedures are designed according to different chemistry properties of these plant growth regulators. The results showed that after spiking of 0. 01-0. 1 mg / kg selected plant growth regulators, average recovery ranged from 70. 0% to 93. 2%and relative standard deviation were 5. 2% -12. 3% . Limit of quantification (LOQ S / N≥10) and limit of detection (LOD S / N≥3) were 0. 01-0. 025 mg / kg and 0. 003-0. 008 mg / kg respectively. The developed purification method is easy, fast and accurate, and can be applied to routine test of plant growth regulators in bean sprout.

OBJECTIVETo assess dietary exposure of diethylhexyl phthalate(DEHP) among Chinese population, including general population, children aged 2-6 years, adolescent aged 7-12, young people aged 13-17, adults aged 18-59 years old as well as older people aged 60 and above and its health risk.

METHODSA total of 6 650 food samples were collected during 2011 to 2013 from 140 local markets of 14 provinces in China, which covered major foods in China. Samples were detected by GC-MS and categorized into 22 food groups. Food consumption data were taken from China National Nutrition and Health Survey performed in 2002 including 68 959 subjects. Mean concentrations of DEHP in food were combined with individual food consumption data to estimate dietary exposure, and food contributors to dietary DEHP intake were also calculated. Then, the exposure was compared with the tolerable daily intake (TDI, 50 µg·kg(-1)-d(-1)) of DEHP.

RESULTSDEHP level in foods (n = 6 650) was in the range of not detected to 43.80 mg/kg. Mean dietary intakes of DEHP in general population was 2.07 (95% CI: 0.06-4.09) µg·kg(-1)·d(-1), accounting for 4.14 percent of TDI (50 µg·kg(-1)·d(-1)). Mean dietary intake for population aged 2-6, 7-12, 13-17, 18-59 as well as elderly aged 60 and above were 3.92 (95% CI: 0.83-7.01), 3.02 (95% CI: 0.69-5.36), 2.17 (95% CI: 0.54-3.81), 1.83 (95% CI: 0.46-3.21) and 1.66 (95% CI: 0.38-2.94) µg·kg(-1)·d(-1) respectively. The 97.5 percentile intakes in the general populations was 4.73 µg·kg(-1)·d(-1), accounting for 9.46% of TDI. Main food sources of DEHP were rice (28.4% (0.59/2.07)), melon solanaceous vegetables (14.7% (0.30/2.07)) and flour (13.2% (0.27/2.07)) for the general population.

CONCLUSIONThe results suggested that dietary exposure to DEHP among Chinese population was lower than tolerable daily intake of DEHP and there were no health concerns based on generally accepted exposure limits. Rice, melon solanaceous vegetables and flour were main food contributors of DEHP dietary intake for Chinese populations.

Adolescent ; Adult ; Aged ; Asian Continental Ancestry Group ; Child ; Child, Preschool ; China ; Diet ; Diet Surveys ; Diethylhexyl Phthalate ; Flour ; Food ; Food Contamination ; Gas Chromatography-Mass Spectrometry ; Humans ; Middle Aged ; Oryza ; Risk Assessment ; Vegetables