气相色谱-负化学离子源质谱测定大豆和玉米中12种三唑类杀菌剂的残留量

Determination of 12 azole fungicide residues in beans and corn by offline disperse solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry

建立了一种可用于大豆和玉米中12种三唑类杀菌剂残留量测定的分散固相萃取-气相色谱-负化学离子源质谱方法。样品经含1％冰醋酸的乙腈提取，分散固相萃取法净化，采用气相色谱．负化学离子源质谱分时段选择离子监测技术进行测定与确证，外标法定量。12种农药在50—1000μg／L范围内线性关系均良好；所有农药的方法定量限（LOQ）均低于8μg／kg；10，20和40μg／kg3个添加水平下所有农药的回收率为70％～130％，相对标准偏差（RSD）≤13．9％。该方法在检测大豆和玉米基质时无干扰现象出现。

A confirmatory method is proposed for the determination of 12 azole fungicide residues in beans and corn with the technique of offline disperse solid phase extraction （DSPE） and gas chromatography-negative chemical ionization mass spectrometry （GC-NCI/MS）. The pesticides interested were extracted from the samples with acetonitrile containing 1% acetic acid and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulfate plus sodium acetate followed by a simple cleanup step known as dispersive solid-phase extraction. The aliquot was determined and confirmed by GC-NCI/MS using external standard method. The recoveries of all pesticides were between 70% and 130% at the three spiked levels, 10 μg/kg, 20 μg/kg and 40 μg/kg. The relative standard deviations were less than 13.9%. The linearity of method was good from 50 to 1 000 μg/L. The limits of quantification （LOQ） were less than 8 μg/kg. The method is selective with no interference and is suitable for the confirmatory of pesticide residues in beans and corn.