RESUMEN
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.
RESUMEN
OBJECTIVE: To analyze the chemical compositions of the essential oils of Eupatorium fortunei extracted by CO2-supercritical-fluid-extraction(SFE-CO2) vs.steam distillation extraction(SD).METHODS: The essential oils of the E.fortunei were extracted by SD vs.SFE-CO2.The chemical components were separated and analyzed by GC-MS.RESULTS: 31 compounds were identified in the essential oils of E.fortunei extracted by SFE-CO2,accounting for 75.97% of the peak area of the total ion-current chromatogram,with 2-propenoic acid-3-(4-methoxyphenyl)-ethyl ester showing the highest proportion(40.50%).21 compounds were identified in the essential oils of E.fortunei extracted by SD,accounting for 51.70% of the peak area of the total ion-current chromatogram,with caryophyllene showing the highest proportion(10.35%).13 components were mutual in both extraction methods.The contents of the components varied greatly.CONCLUSION: SFE-CO2 is more stable and reliable and reproducible than SD,and it is more applicable for the extraction of the essential oils from Chinese herbal medicine.