应用高效液相色谱法(HPLC)测定了玉米淀粉中3种禁用的脲衍生物农药,即氯磺隆、枯草隆及定虫隆.试样中的上述农药用甲醇超声萃取,所得萃取液经蒸发并用氮气吹干后溶于1 mL甲醇中供HPLC测定用.用ZORBAX Eclipse XDB-C18色谱柱(2.1 mm×150 mm,5 μm)作为固定相,并用不同比例配成的乙腈和水的混合液作为流动相进行梯度淋洗,采用220 nm波长的列阵二极管检测器进行检测.3种农药的线性范围均在0.2~100.0 mg·L-1范围内,方法的检出限(S/N=3)为0.04 mg·kg-1(氯磺隆),0.03 mg·kg-1(枯草隆)及0.01 mg·kg-1(定虫隆).以玉米淀粉样品作基体用标准加入法作方法回收试验和精密度试验,测得上述3种农药的平均回收率(n=5)依次为92.0%,93.4%及95.9%;相对标准偏差(n=6)依次为3.5%,2.7%及3.8%.

Three prohibited pesticides of urea derivatives,i.e. chlorsulfuron,chlorofluazuron and chloroxuron,in corn starch were determined by HPLC. The pesticides in sample were extracted with methanol ultrasonically and the extract obtained was evaporated and blown to dryness with nitrogen. One mL of methanol was added to dissolve the residue and the solution was used for HPLC determination. The chromatographic column of ZORBAX Eclipse XDB-C18 (2.1 mm×150 mm,5 μm) was used as stationary phase,and mixtures of acetonitrile and water in different proportions were used as mobile phase in the gradient elutions. UV-detection at 220 ℃ with DAD was adopted in the determinations. Linear relationships between values of peak area and concentration of the pesticides were obtained in the same range of 0.2-100.0 mg·L-1 for all the 3 pesticides. Detection limits (S/N=3) found was 0.04 mg·kg-1 for chlorsulfuron,0.03 mg·kg-1 for chlorfluazuron and 0.01 mg·kg-1 for chloroxuron. Test for recovery and precision of the method were tested,giving values of average recovery (n=5) 92.0%,93.4% and 95.9%,and values of RSD′s (n=6) 3.5%,2.7% and 3.8% for the 3 pesticides respectively.