嘧草醚在水稻及其环境中的残留

采用改良的QuEChERS-高效液相色谱-质谱 (HPLC-MS) 技术，建立了嘧草醚在水稻及其环境中残留量的检测方法。样品经V (乙腈) : V (甲酸) = 199 : 1的混合溶液提取，由十八烷基键合硅胶 (C₁₈) 或C₁₈ + 丙基乙二胺 (PSA) 吸附剂净化。以V (乙腈) : V (0.1%甲酸水溶液) = 70 : 30的混合溶液为流动相，经ZORBAX Eclipse XDB-C₁₈色谱柱分离，采用电喷雾正离子 (ESI+) 模式扫描，HPLC-MS检测，外标法定量。结果表明:在0.01~1 mg/L范围内嘧草醚的峰面积与其质量浓度间线性关系良好，在乙腈、稻田水、土壤、稻株、糙米和稻壳中的相关系数均大于0.99。嘧草醚在稻田水中的检出限 (LOD) 为0.0015 mg/L，定量限 (LOQ) 为0.005 mg/L，在土壤、糙米、稻壳和稻株中的LOD分别为0.003、0.015、0.015 和0.003 mg/kg，LOQ分别为0.01、0.05、0.05 和0.01 mg/kg。在0.005、0.01和0.1 mg/L (或mg/kg) 添加水平下，嘧草醚在稻田水、土壤和糙米中的平均回收率分别为95~109%、92%~106%和89%~107%，相对标准偏差 (RSD) 分别为3.0%~5.0%、1.1%~2.9%和3.1%~3.7%；在稻壳和稻株中的平均回收率分别为95%~102%和93%~107%，RSD分别为1.1%~3.8%和3.5%~9.9%。该方法灵敏度、精密度和准确度均符合农药残留分析要求。

Residue of pyriminobac-methyl in rice and environment

A method was developed for the determination of pyriminobac-methyl residues in rice and environment by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) coupled with modified QuEChERS. The samples were extracted with a solvent mixture, V (acetonitrile):V (formic acid)=199:1, and then purified by octadecylsilane bonded silica (C₁₈) or C₁₈ + primary secondary amine (PSA) adsorbents. The analytes were separated on a ZORBAX SB C₁₈ column using a solvent mixture, V (acetonitrile):V (0.1% formic acid aqueous solution)=70:30, as mobile phase. Pyriminobac-methyl was detected by HPLC-MS with an electrospray ionization source (ESI⁺) in positive mode. Quantization was performed using external standard method. The results showed good linear relationship between the peak area of pyriminobac-methyl and its mass concentration in the range from 0.01 mg/L to 1 mg/L. And the correlation coefficients in acetonitrile, paddy water, soil, rice stalk, brown rice and rice husk were all above 0.99. The limit of detection (LOD) for pyriminobac-methyl was 0.0015 mg/L in paddy water, while the limit of quantification (LOQ) was 0.005 mg/L. The LOD were 0.003, 0.015, 0.015 and 0.003 mg/kg in soil, brown rice, rice hull and rice stalk, respectively, while the corresponding LOQ were 0.01, 0.05, 0.05 and 0.01 mg/kg, respectively. The average spiked recoveries of pyriminobac-methyl at three spiked levels of 0.005, 0.01 and 0.1 mg/L (or mg/kg) in paddy water, soil and brown rice were 95%-109%, 92%-106% and 89%-107%, respectively, with the relative standard deviation (RSD) of 3.0%-5.0%, 1.1%-2.9% and 3.1%-3.7%, respectively. The average spiked recoveries in rice hull and rice stalk were 95%-102% and 93%-107%, respectively, with the RSD of 1.1%-3.8% and 3.5%-9.9%, respectively. The sensitivity, precision and accuracy of the method meet the requirements of pesticide residue analysis.