分散液相微萃取-气相色谱联用测定葡萄中百菌清、克菌丹和灭菌丹残留

Dispersive Liquid-liquid Microextraction Method Coupled with Gas Chromatography for Determination of Chlorothalonil,Captan and Folpet Residues in Grape Samples

采用分散液相微萃取与气相色谱-电子捕获检测联用技术建立了测定葡萄样品中百菌清、克菌丹和灭菌丹农药残留的新方法。对影响萃取和富集效率的因素进行了优化。萃取条件选定为在10mL带塞离心试管中加入5.0mL葡萄样品溶液,并加入1.0mL丙酮(分散剂),振荡摇匀后以5000r/min离心5min,然后将上层清液转移至另一离心试管中,加10.0μL氯苯(萃取剂),分散混匀后再以5000r/min离心5min,萃取剂氯苯相沉积到试管底部,吸取1.0μL萃取相直接进样分析。在优化的实验条件下,3种杀菌剂的富集倍数可达788～876倍;检出限在6.0～8.0μg/kg(S/N=3:1)范围内。以α-六六六为内标,测定3种杀菌剂的线性范围为10～150μg/kg,线性相关系数在0.9990～0.9995范围内。本方法已成功应用于葡萄样品中百菌清、克菌丹和灭菌丹残留的测定,平均加标回收率在92.3%～106.1%范围内;相对标准偏差在4.5%～7.2%之间,结果令人满意。

A novel method was developed for the determination of chlorothalonil, captan and folpet in grape samples by dispersive liquid-liquid microextraction （DLLME） coupled with gas chromatography-electron capture detection （GC-ECD）. Some important parameters that affect the extraction efficiency of DLLME were studied. In this method, 5.00 mL grape sample solution was placed in a 10-mL screw cap glass tube with conic bottom and 1 mL of acetone （ as disperser solvent） was added into it. After the mixture was gently shaken, it was centrifuged at 5000 r/rain for 10 rain. Then the supernatant was transferred to another same type tube, wherin 9 μL chlorobenzene （ as extraction solvent） was added. The mixture was gently shaken for several seconds and a cloudy solution （water/acetone/ehlorobenzene） was formed in the tube. After eentrifugation at 5000 r/min for 5.0 min, 1.0 μL of the sedimented the enrichment factors the chlorobenzene phase was sedimented at the bottom of the centrifuge tube. phase was taken and ranged from 788 to 876. injected into GC for analysis. Under the optimum conditions, Using or-benzene hexachloride as the internal standard, the linear range for the determination was 10 - 150 μg/kg and the limits of detection were from 6.0 to 8.0 μg/kg （ S/N = 3：1 ）, with the correlation coefficients （r） varying from 0. 9990 to 0. 9995. The recoveries ranged from 92.3% to 106.1% with the relative standard deviations falling between 4.5% and 7.2%. Grape samples were successfully analyzed by the proposed method with satisfactory results.