Departamento de Medio Ambiente, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Ctra. de La Coruña km 7, 28040 Madrid, Spain.
J Chromatogr A. 2010 Mar 26;1217(13):1989-94. doi: 10.1016/j.chroma.2010.01.077. Epub 2010 Feb 6.
Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500 microL of 840 mM NaOH was added to 3 mL of orange juice in order to compensate the acidity of the samples and to adjust pH into the alkaline region. Analytes were extracted in their neutral state through a supported liquid membrane (SLM) of 2-octanone into 20 microL of a stagnant aqueous solution of 10 mM HCl inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to analysis. Capillary electrophoresis (CE) was used during the optimization of the extraction procedure. Working under the optimized extraction conditions, LPME effectively extracted the analytes from different orange juices, regardless of different pH or solid material (pulp) present in the sample, with recoveries that ranged between 17.0 and 33.7%. The analytical performance of the method was evaluated by liquid chromatography coupled with mass spectrometry (LC/MS). This technique provided better sensitivity than CE and permitted the detection below the microg L(-1) level. The relative standard deviations of the recoveries (RSDs) ranged between 3.4 and 10.6%, which are acceptable values for a manual microextraction technique without any previous sample treatment, using a home-built equipment and working under non-equilibrium conditions (30 min extraction). Linearity was obtained in the range 0.1-10.0 microg L(-1), with r=0.999 and 0.998 for TBZ and IMZ, respectively. Limits of detection were below 0.1 microg L(-1) and are consistent with the maximum residue levels permitted for pesticides in drinking water, which is the most restrictive regulation applicable for these kinds of samples. It has been demonstrated the suitability of three-phase LPME for the extraction of pesticides from citrus juices, suppressing any pretreatment step such as filtration or removal of the solid material from the sample, that may potentially involve a loss of analyte.
基于聚丙烯中空纤维的液相微萃取（LPME）被评估用于从橙汁中萃取采后杀菌剂噻菌灵（TBZ）、多菌灵（CBZ）和抑霉唑（IMZ）。直接 LPME 在萃取前无需任何样品预处理，使用简单的自制设备进行。将 500µL 的 840mM NaOH 加入 3mL 橙汁中，以补偿样品的酸度并将 pH 调整到碱性区域。在中性状态下，通过中空纤维内腔中的 2-辛酮支撑液膜（SLM）将分析物萃取到 20µL 的 10mM HCl 静止水溶液中。随后，直接对接受溶液进行分析。在优化萃取过程中使用毛细管电泳（CE）。在优化的萃取条件下，LPME 能够有效地从不同的橙汁中萃取分析物，无论样品中的 pH 或固体物质（果肉）如何，回收率在 17.0%至 33.7%之间。该方法的分析性能通过液相色谱-质谱联用（LC/MS）进行评估。与 CE 相比，该技术提供了更好的灵敏度，并允许在微克 L(-1) 以下水平进行检测。回收率的相对标准偏差（RSD）在 3.4%至 10.6%之间，这是一种无需任何样品预处理的手动微萃取技术在使用自制设备并在非平衡条件下（30 分钟萃取）下的可接受值。在 0.1-10.0µg L(-1) 范围内获得了线性，TBZ 和 IMZ 的 r 值分别为 0.999 和 0.998。检测限低于 0.1µg L(-1)，与饮用水中允许的农药最大残留限量一致，这是适用于此类样品的最严格规定。已经证明三相 LPME 适用于从柑橘汁中萃取农药，无需任何预处理步骤，如过滤或从样品中去除固体物质，这可能会导致分析物损失。
