固相微萃取-气相色谱法和气相色谱-质谱法测定茶叶中氟虫腈及其代谢物残留

基于固相微萃取-气相色谱(SPME-GC)建立了检测茶叶中氟虫腈及其代谢物(脱亚硫酰基氟虫腈、硫化氟虫腈、氟虫腈砜、酰胺氟虫腈)残留的分析方法。实验中采用85 μm聚丙烯酸酯(PA)萃取头,萃取温度为60 ℃,萃取缓冲体系的pH值为9。当添加水平为2～10 μg/kg时,回收率在71.2%～109.3%之间,相对标准偏差(RSD)在1.2%～7.1%之间。方法的检出限(LOD)和定量限(LOQ)分别在0.3～1.2 μg/kg和1.0～4.0 μg/kg之间。对所建立的方法采用气相色谱-质谱(GC-MS)进行确证,结果令人满意。本方法灵敏度、精密度和LOD均符合残留分析要求,具有快速、灵敏度高的特点,适合于茶叶中氟虫腈及其代谢物残留的痕量分析。

Determination of fipronil and its metabolites in tea by solid-phase microextraction coupled with gas chromatography and gas chromatography-mass spectrometry

An effective multi-residue method for the trace analysis of fipronil and four metabolites (fipronil-desulfinyl, fipronil-sulfide, fipronil-sulfone and fipronil-carboxamide) in tea was developed based on solid-phase microextraction coupled with gas chromatography (SPME-GC). The targets were extracted with a fused-silica fiber coated with 85 microm polyacrylate (PA). The extraction was performed in a pH 9 buffer (containing 0.1 mol/L boracic acid, 0.1 mol/L KCI and 0.1 mol/L NaOH) at 60 degrees C and under 2500 r/min for 30 min. With the concentration range of 2-10 microg/kg, the recoveries ranged from 71.2% to 109.3% and the relative standard deviations (RSDs) were lower than 10% (n = 6). The limits of detection (LODs) and limits of quantitation (LOQs) of the studied compounds ranged from 0.3 microg/kg to 1.2 microg/kg and 1.0 microg/kg to 4.0 microg/kg, respectively, with the values well below the residue limits set by Japan, European Union and China. By the proposed method, 1 positive samples of 30 tea samples were found with fipronil and fipronil-sulfone. The identification of the method was done by gas chromatography-mass spectrometry (GC-MS). The method can be applied as a monitoring tool for tea, in the investigation of food to fipronil and its metabolites.