取经粉碎及预处理的样品25 g,加乙腈50 mL超声提取10 min,滤入盛有5 g氯化钠的量筒中,振荡1 min并静置待两相分层.移取乙腈相20 mL,于70℃水浴中吹氮至近干,加入丙酮溶解残渣并定容为5.0 mL,供气相色谱分析.采用(色谱柱1)DB-17毛细管柱(脉冲不分流进样,进样量5μL)进行分离和初筛,发现疑似阳性样品,再用(色谱柱2)HP-5毛细管柱(不分流进样,进样量为1μL)进行分离和佐证.采用FPD+检测器,外标法定量.灭线磷、甲拌磷、甲拌磷砜、甲拌磷亚砜及三唑磷的线性范围均为0.02~0.20 mg·L-1,检出限(3S/N)为1.0~3.0 μg·kg-1(色谱柱1)和1.5~2.0μg·kg-1(色谱柱2);加标回收率分别为79.6%~119%和76.2%~116%;测定值的相对标准偏差(n=10)分别为2.8%~8.8%和2.7%~8.4%.
A portion (25 g) of the smashed and pretreated sample was extracted ultrasonically with 50 rnL of acetonitrile for 10 min and filtered.The filtrate was shaked with 5 g of NaC1 and stayed for phase separation.The acetonitrile phase 20 mL was taken and evaporated to near dryness by N2-blowing in a water-bath at 70 ℃C.The residue was taken up and made up to 5.0 mL with acetone for GC analysis.An aliquot of 5 μL was introduced into GC-column 1 (DB-17 capillary column,with pulse-nonsplitting sample introduction) for separation and preliminary screening.In happening of positive sample,another aliquot (1μL) of the acetone solution should be taken for proof by separation on GC-column 2 (HP-5 capillary column,with non-splitting sample introduction).FPD+ detector and quantification by external standard method were used in both cases.Linearity ranges were found same between 0.02-0.20 mg · L 1 for ethoprophos,phorate,phorate-sulfone,phorate-sulfoxide and triazophos for both columns.Detection limits (3S/N) were 1.0-3.0 μg · kg 1 for GC-column 1 and 1.5-2.0 μg · kg 1 for GC-column 2.Values of recovery found by standard addition method ranged from 79.6% to 119% and from 76.2% to116%,and RSDs (n=10) were 2.8%-8.8% and 2.7%-8.4% for the 2 columns respectively.