Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Casilla 233, Santiago, Chile.
Talanta. 2011 Oct 15;85(5):2425-9. doi: 10.1016/j.talanta.2011.07.087. Epub 2011 Jul 30.
The rotating disk sorptive extraction (RDSE) technique was applied to the determination of pesticides in aqueous samples. Pesticides of different polarities were considered in this study: chlorpyrifos, diazinon, fenvalarate, cyhalothrin, cypermethrin, lindane and malathion. The sorptive/desorptive behavior of the pesticides was studied using a rotating disk containing a polydimethylsiloxane (PDMS) phase on one of its surfaces. The analyte polarity was a significant factor in the extraction time; shorter extraction times were required for the more apolar pesticides. The optimum variables for the extraction of all analytes were: extraction time of 3h, sample volume of 25 mL, rotational velocity of the disk 1250 rpm, desorption time of 30 min using methanol. For pesticides with values of Log K(ow)>4, the extraction time can be reduced to 30 min for a quantitative extraction. Under these conditions, recoveries between 76% and 101% were obtained for the target pesticides, and the repeatability of the methodology, expressed as relative standard deviation, was determined to be between 10% and 20%. Additionally, the limits of detection of the analytes were lower than 3.1 μg L(-1). The extraction method developed using the RDSE was compared to a stir bar sorptive extraction (SBSE) under the same conditions. It can be observed that the extraction using the rotating disk offers higher recoveries because of its higher PDMS volume and its higher surface area to volume ratio that allows for improved mass transfer.
旋转圆盘固相萃取（RDSE）技术被应用于水样中农药的测定。本研究考虑了不同极性的农药：毒死蜱、二嗪磷、氰戊菊酯、氯氟氰菊酯、氯菊酯、林丹和马拉硫磷。采用旋转圆盘上的聚二甲基硅氧烷（PDMS）相来研究农药的吸附/解吸行为。分析物的极性是影响萃取时间的重要因素；对于更非极性的农药，需要更短的萃取时间。所有分析物的最佳萃取条件为：萃取时间 3h，样品体积 25mL，圆盘转速 1250rpm，用甲醇解吸 30min。对于 Log K(ow)>4 的农药，萃取时间可缩短至 30min 即可进行定量萃取。在这些条件下，目标农药的回收率在 76%至 101%之间，方法的重复性（以相对标准偏差表示）在 10%至 20%之间。此外，分析物的检出限低于 3.1μg/L。在相同条件下，将开发的 RDSE 与搅拌棒吸附萃取（SBSE）进行了比较。可以观察到，由于旋转圆盘具有更高的 PDMS 体积和更高的表面积与体积比，因此可以实现更好的质量传递，从而提供更高的回收率。
