Research Institute for Pesticides and Water, University Jaume I, Castellón, Spain.
Anal Bioanal Chem. 2012 Mar;402(7):2287-300. doi: 10.1007/s00216-011-5431-3. Epub 2011 Oct 8.
Monitoring pesticide residues in tropical fruits is of great interest for many countries, e.g., from South America, that base an important part of their economy on the exportation of these products. In this work, a LC-MS/MS multi-residue method using a triple quadrupole analyzer has been developed for around 30 pesticides in seven Colombian tropical fruits of high commercial value for domestic and international markets (uchuva, tamarillo, granadilla, gulupa, maracuya, papaya, and pithaya). After sample extraction with acetonitrile, an aliquot of the extract was diluted with water and directly injected into the HPLC-MS/MS system (electrospray interface) without any cleanup step. The formation of sodium adducts-of poor fragmentation-was minimized using 0.1% formic acid in the mobile phase, which favored the formation of the protonated molecule. However, the addition of ammonium acetate made the formation of the ammonium adducts in some particular cases possible, avoiding the presence of the sodium adducts. The highest sensitivity was observed in positive electrospray ionization for the wide majority of pesticides, with a few exceptions for acidic compounds that gave better response in the negative mode (e.g., 2,4-D, fluazinan). Thus, simultaneous acquisition on the positive/negative mode was applied. Two MS/MS transitions were acquired for each compound to ensure a reliable quantification and identification of the compounds detected in samples, although for malathion a third transition was acquired due to the presence of interfering isobaric compounds in the sample extracts. A detailed study of matrix effects was made by a comparison of standards in solvent and in matrix. Both ionization suppression and ionization enhancement were observed depending on the analyte/matrix combination tested. Correction of matrix effects was made by the application of calibration in matrix. Three matrices were selected (uchuva, maracuya, gulupa) to perform matrix calibration in the analysis of all seven fruit varieties studied. The method was validated by recovery experiments in samples spiked at two levels (0.05 and 0.5 mg/kg). The data were satisfactory for the wide majority of analyte/matrix combinations, with most recoveries between 70% and 110% and the RSD below 15%. Several samples collected from the market were finally analyzed. Positive findings were confirmed by evaluating the experimental Q/q ratios and retention times, and comparing them with those of reference standards.
监测热带水果中的农药残留对于许多国家非常重要，例如南美洲的国家，这些国家的经济很大程度上依赖于这些产品的出口。在这项工作中，开发了一种使用三重四极杆分析仪的 LC-MS/MS 多残留方法，用于分析七种具有高商业价值的哥伦比亚热带水果中的约 30 种农药，这些水果在国内外市场上都有销售（百香果、树番茄、刺果番荔枝、人心果、西番莲、木瓜和火龙果）。在乙腈提取样品后，取一部分提取物用纯水稀释，无需任何净化步骤，直接注入 HPLC-MS/MS 系统（电喷雾接口）。在流动相中使用 0.1%甲酸可最小化形成（碎裂较差的）钠离子加合物，有利于形成质子化分子。然而，在某些情况下加入乙酸铵可形成铵加合物，从而避免形成钠离子加合物。在正电喷雾电离模式下，大多数农药的灵敏度最高，只有少数酸性化合物在负离子模式下的响应更好（例如 2,4-D、氟磺胺草醚）。因此，应用了正/负模式同时采集。对于每种化合物，都采集了两个 MS/MS 转换，以确保对样品中检测到的化合物进行可靠的定量和鉴定，尽管对于马拉硫磷，由于样品提取物中存在干扰的同量异位化合物，因此采集了第三个转换。通过比较溶剂和基质中的标准品，对基质效应进行了详细研究。根据测试的分析物/基质组合，观察到了抑制和增强电离两种情况。通过基质校正来校正基质效应。选择了三个基质（百香果、西番莲、人心果）来校正分析所有七种研究水果品种的基质校准。该方法通过在两个水平（0.05 和 0.5 mg/kg）对样品进行加标回收实验进行验证。对于大多数分析物/基质组合，数据令人满意，大多数回收率在 70%至 110%之间，相对标准偏差（RSD）低于 15%。最后对从市场上采集的几个样品进行了分析。通过评估实验 Q/q 比和保留时间，并与参考标准进行比较，确认了阳性结果。
