葱、姜、蒜、洋葱、韭菜、蒜苔等复杂基质蔬菜样品中六六六、滴滴涕、四氯硝基苯、五氯硝基苯、艾氏剂等11种农药残留用丙酮-正己烷(1+1)混合溶剂均质提取,加入20 g·L-1硫酸钠溶液用正己烷进行液-液分配,提取液用浓硫酸净化后所得有机相在13 kPa压力条件下进行旋转蒸发至近干,用正己烷使残渣溶解并定容为1.0 mL,用于气相色谱法测定.采用DB-1701毛细管柱分离,用气相色谱-微池电子捕获检测器检测,在2个不同浓度水平上加入11种农药混合标准溶液进行回收试验,测得其回收率在81.6%~97.1%之间,测定值的相对标准偏差(n=6)均小于7.5%.该方法的检出限(3S/N)为0.5 μg·kg-1.

Eleven pesticides of residual amounts (including BHC,DDT,tecnazene,quirtozene,aldrin and etc.) were extracted from samples of vagetables of complex matrixes with mixed solvent of acetone and n-hexane (mixed in the ratio of 1 to 1 by volume),and partitioned with 20 g·L-1 Na2SO4 solution. The n-hexane extract was purified by shaking with conc. H2SO4. After removing the H2SO4 phase,the hexane phase was washed with 20 g·L-1 Na2SO4 solution,and dehydrated with anhydrous Na2SO4. Then the solution in n-hexane was evaporated to near dryness by rotary evaporation under 13 kPa. The residue was taken and made up to 1.0 mL with n-hexane and used for GC determination. After separation on the DB 1701 capillary column,GC determination was carried out with μ-ECD. Recovery tests were made at 2 concentration levels by addition of mixed standard solution of the 11 pesticides to 4 kinds of vegetables as the matrixes,results of recovery found were in the range from 81.6% to 97.1%,with RSD′s (n=6) less than 7.5%. Detection limit (3S/N) of the method found was 0.5 μg·kg-1.