Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea; Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, 12211 Giza, Egypt; Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701, Republic of Korea.
Food Chem. 2015 May 1;174:248-55. doi: 10.1016/j.foodchem.2014.11.052. Epub 2014 Nov 14.
A simultaneous method was developed to analyse thiamethoxam and its metabolite clothianidin in Swiss chard using tandem mass spectrometry (in the positive electrospray ionisation mode using multiple reaction monitoring mode) to estimate the dissipation pattern and the pre-harvest residue limit (PHRL). Thiamethoxam (10%, WG) was sprayed on Swiss chard grown in two different areas under greenhouse conditions at the recommended dose rate of 10 g/20 L water. Samples were collected randomly up to 14 days post-application, extracted using quick, easy, cheap, effective, rugged, safe (QuEChERS) acetate-buffered method and purified via a dispersive solid phase extraction (d-SPE) procedure. Matrix matched calibration showed good linearity with determination coefficients (R(2)) ⩾ 0.998. The limits of detection (LOD) and quantification (LOQ) were 0.007 and 0.02 mg/kg. The method was validated in triplicate at two different spiked concentration levels. Good recoveries (n=3) of 87.48-105.61% with relative standard deviations (RSDs) < 10 were obtained for both analytes. The rate of disappearance of total thiamethoxam residues in/on Swiss chard was best described by first-order kinetics with half-lives of 6.3 and 4.2 days. We predicted from the PHRL curves that if the residues were <19.21 or 26.98 mg/kg at 10 days before harvest, then total thiamethoxam concentrations would be below the maximum residue limits during harvest.
建立了一种同时分析噻虫嗪及其代谢物噻虫胺在瑞士菠菜中的残留量的方法，采用串联质谱法（正电喷雾电离模式，多反应监测模式），以评估其消解动态和休药期残留限量（PHRL）。噻虫嗪（10%，WG）以推荐剂量 10 g/20 L 水施用于在温室条件下生长的两个不同地区的瑞士菠菜。施药后 14 天内随机采集样品，使用快速、简便、廉价、有效、耐用、安全（QuEChERS）缓冲乙酸盐提取法提取，通过分散固相萃取（d-SPE）程序净化。基质匹配校准显示出良好的线性关系，决定系数（R(2)）≥0.998。检测限（LOD）和定量限（LOQ）分别为 0.007 和 0.02 mg/kg。该方法在两个不同的加标浓度水平下进行了三次重复验证。两种分析物的回收率（n=3）均为 87.48-105.61%，相对标准偏差（RSD）<10。瑞士菠菜中总噻虫嗪残留量的消失速度最好用一级动力学描述，半衰期分别为 6.3 和 4.2 天。根据 PHRL 曲线预测，如果在收获前 10 天的残留量<19.21 或 26.98 mg/kg，则总噻虫嗪浓度在收获期间将低于最大残留限量。
