Kharbouche L, Gil García M D, Lozano A, Hamaizi H, Galera M Martínez
Department of Chemistry, University Ahmed Ben Bella 1, Oran, Algeria.
Department of Chemistry and Physics, Area of Analytical Chemistry, University of Almería, 04120 Almería, La Cañada de San Urbano, Spain; Campus de Excelencia Internacional Agroalimentario CeiA3, 04120 Almería, La Cañada de San Urbano, Spain.
Talanta. 2019 Jul 1;199:612-619. doi: 10.1016/j.talanta.2019.02.092. Epub 2019 Feb 28.
This paper describes the synthesis of a silica based MSU-1 mesoporous solid and its application as sorbent in solid-phase extraction to pre-concentrate thirteen pesticides of low-high polarity (methomyl, cymoxanil, carbofuran, monolinuron, isoproturon, methidathion, methiocarb, malathion, phosalone, diazinon, penconazole, neburon and chlorotoluron) in ground and river water. The synthesis was based in an H-bonding interaction assembling (IN) between two non-ionic components (the inorganic silica surface, I and the polyethylene oxide template, N) by adding tetraethoxysilane to the non-ionic surfactant Brij®100, the latter previously dissolved in HCl 1 M. 50 mL water samples adjusted at pH= 3.5 were passed, at a flow rate of 5 mL/min, through a home-made cartridge containing 50 mg of MSU-1 sorbent, pre-conditioned with 5 mL of ultrapure water; then, the cartridge was washed with 5 mL of ultrapure water. Following elution with 5 mL of acetonitrile, the pesticides were determined by ultra performance liquid chromatography coupled to triple quadrupole-mass spectrometry. Two selected reaction monitoring transitions were monitored per compound, the most intense one being used for quantification and the second one for confirmation. Three points were used for identification, as established in the Directive 96/23/EC for LC-MS/MS analysis, which deals with confirmatory methods for organic residues and contaminants listed in the Group B (veterinary drugs and contaminants). Medium matrix effect (|20%|<ME<|50%|) was found for methiocarb and malathion, whereas diazinon and phosalone showed strong matrix effect (ME≥>|50%|). Therefore, the standard addition methodology was applied by adding an adequate amount of the pesticide standard mixture to the final sample extract. All pesticides were quantified using this approach for practical reasons, thus avoiding two different calibrations. The method quantification limit (MQL) of pesticides was 0.01 μg/L for all of them, except for diazinon (0.1 μg/L). Recoveries of the target pesticides at MQL and 0.25 µg/L concentration levels in blank river water were in the range 70.1-113.5% and 86.7-107.3%, respectively, with RSDs lower than 16.3% and 15.7%, respectively. Four ground water samples and three river water samples, taken from Almería (Spain), were analyzed by the proposed method and only phosalone at a concentration level of 0.05 µg/L was found in one river water sample.
本文描述了一种基于二氧化硅的MSU-1介孔固体的合成及其作为吸附剂在固相萃取中的应用，用于预富集地表水和河水中13种低至高极性的农药（灭多威、霜脲氰、克百威、绿麦隆、异丙隆、杀扑磷、甲硫威、马拉硫磷、伏杀硫磷、二嗪农、戊唑醇、绿谷隆和绿麦隆）。合成基于通过将四乙氧基硅烷添加到非离子表面活性剂Brij®100中，使两种非离子成分（无机二氧化硅表面，I和聚环氧乙烷模板，N）之间形成氢键相互作用组装（IN），后者预先溶解在1 M盐酸中。将50 mL pH = 3.5的水样以5 mL/min的流速通过一个自制的柱管，该柱管含有50 mg预先用5 mL超纯水预处理过的MSU-1吸附剂；然后，用5 mL超纯水冲洗柱管。用5 mL乙腈洗脱后，通过超高效液相色谱-三重四极杆质谱联用仪测定农药。每种化合物监测两个选定反应监测跃迁，强度最大的用于定量，第二个用于确证。根据96/23/EC指令中关于液相色谱-串联质谱分析的规定，使用三个点进行鉴定，该指令涉及B组（兽药和污染物）中列出的有机残留物和污染物的确证方法。发现甲硫威和马拉硫磷存在中等基质效应（|20%|<ME<|50%|），而二嗪农和伏杀硫磷表现出强烈的基质效应（ME≥|50%|）。因此，采用标准加入法，向最终样品提取物中加入适量的农药标准混合物。出于实际原因，所有农药均使用此方法进行定量，从而避免了两种不同的校准。除二嗪农（0.1 μg/L）外，所有农药的方法定量限（MQL）均为0.01 μg/L。空白河水中目标农药在MQL和0.25 μg/L浓度水平下的回收率分别在70.1 - 113.5%和86.7 - 107.3%范围内，相对标准偏差分别低于16.3%和15.7%。采用所提出的方法对取自西班牙阿尔梅里亚的4个地下水样品和3个河流水样品进行了分析，仅在一个河流水样品中发现了浓度为0.05 μg/L的伏杀硫磷。
