ABSTRACT
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.
ABSTRACT
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.