Grande-Martínez Ángel, Arrebola Francisco Javier, Moreno Laura Díaz, Vidal José Luis Martínez, Frenich Antonia Garrido
J AOAC Int. 2015 Sep-Oct;98(5):1186-98. doi: 10.5740/jaoacint.SGE4-Grande-Martinez.
A rapid and sensitive multiresidue method was developed and validated for the determination of around 100 pesticides in dry samples (rice and wheat flour) by ultra-performance LC coupled to a triple quadrupole mass analyzer working in tandem mode (UPLC/QqQ-MS/MS). The sample preparation step was optimized for both matrixes. Pesticides were extracted from rice samples using aqueous ethyl acetate, while aqueous acetonitrile extraction [modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method] was used for wheat flour matrixes. In both cases the extracts were then cleaned up by dispersive solid phase extraction with MgSO4 and primary secondary amine+C18 sorbents. A further cleanup step with Florisil was necessary to remove fat in wheat flour. The method was validated at two concentration levels (3.6 and 40 μg/kg for most compounds), obtaining recoveries ranging from 70 to 120%, intraday and interday precision values≤20% expressed as RSDs, and expanded uncertainty values≤50%. The LOQ values ranged between 3.6 and 20 μg/kg, although it was set at 3.6 μg/kg for the majority of the pesticides. The method was applied to the analysis of 20 real samples, and no pesticides were detected.
建立了一种快速灵敏的多残留方法，并通过超高效液相色谱-串联三重四极杆质谱仪（UPLC/QqQ-MS/MS）对干燥样品（大米和小麦粉）中的约100种农药进行了测定和验证。针对两种基质对样品前处理步骤进行了优化。大米样品中的农药采用乙酸乙酯水溶液提取，而小麦粉基质采用乙腈水溶液提取[改良的QuEChERS（快速、简便、廉价、有效、耐用且安全）方法]。在这两种情况下，提取物随后均通过用硫酸镁和伯仲胺+C18吸附剂进行分散固相萃取来净化。为去除小麦粉中的脂肪，需要用弗罗里硅土进行进一步的净化步骤。该方法在两个浓度水平（大多数化合物为3.6和40 μg/kg）下进行了验证，回收率在70%至120%之间，日内和日间精密度值以相对标准偏差表示≤20%，扩展不确定度值≤50%。定量限（LOQ）值在3.6至20 μg/kg之间，不过大多数农药的定量限设定为3.6 μg/kg。该方法应用于20个实际样品的分析，未检测到农药。
