固相萃取气相色谱法测定茶叶中5种有机磷农药残留

Determination of 5 organophosphorus pesticide residues in teas by solidphase extraction and gas chromatography

目的 建立固相萃取气相色谱法同时测定茶叶中敌敌畏、甲胺磷、乙酰甲胺磷等5 种有机磷农药残留. 方法 样品用固相萃取法萃取,乙酸乙酯/丙酮混合液洗脱,旋转蒸发仪浓缩,丙酮溶解定容,气相色谱柱分离后检测. 检测器温度260 ℃,进样口温度250 ℃. 燃气为氢气,流速80 mL/min. 载气为氮气,流速10 mL/min. 助燃气为空气,流速为100 mL/min. 结果 该方法检出限为0 . 01-0 . 02 mg/kg. 当加入标准溶液的浓度为0. 25 mg/kg时,加标回收率为74. 9% -88. 9%,RSD在2. 4% -10. 3%范围之间;当加入标准溶液的浓度为1. 0 mg/kg时,加标回收率为87. 9% -100%,RSD在1. 7% -5. 0%范围内. 结论 固相萃取气相色谱法检测效率高,适合大量样品的筛选和检测.

Objective To develop a solid-phase extraction and gas chromatography method for determination of 5 or-ganophosphorus pesticide residues in teas,such as dichlorvos,methamidophos,acephate and so on. Methods The samples were extracted by solid-phase extraction,eluted by ethyl acetate and acetone mixture,enriched by rotary evap-orator,diluted with acetone,separated and detected by gas chromatography. The temperature of detector and injection port were 260℃ and 250℃ respectively. The fuel gas was hydrogen and the flow rate was 80 mL/min. The carrier gas was nitrogen and the flow rate was 10 mL/min. The oxidant gas was air and the flow rate was 100 mL/min. Results The limit of detection were in range of 0. 01-0. 02 mg/kg. The recovery at the concentration of 0. 25 mg/kg was in the range of 74. 9% -88. 9% with relative standard deviations（ RSD） in the range of 2. 4% -10. 3%. The recovery at the concentration of 1 . 0 mg/kg was in the range of 87 . 9% -100% with RSD in the range of 1 . 7% -5 . 0%. Conclusion The solid-phase extraction and gas chromatography method was more efficient and could be used to screen and examine large sum of samples.