Pedersen-Bjergaard S, Rasmussen K E
School of Pharmacy, University of Oslo, Norway.
Anal Chem. 1999 Jul 15;71(14):2650-6. doi: 10.1021/ac990055n.
Methamphetamine as a model compound was extracted from 2.5-mL aqueous samples adjusted to pH 13 (donor solution) through a thin phase of 1-octanol inside the pores of a polypropylene hollow fiber and finally into a 25-microL acidic acceptor solution inside the hollow fiber. Following this liquid-liquid-liquid microextraction (LLLME), the acceptor solutions were analyzed by capillary zone electrophoresis (CE). Extractions were performed in simple disposable devices each consisting of a conventional 4-mL sample vial, two needles for introduction and collection of the acceptor solution, and a 8-cm piece of a porous polypropylene hollow fiber. From 5 to 20 different samples were extracted in parallel for 45 min, providing a high sample capacity. Methamphetamine was preconcentrated by a factor of 75 from aqueous standard solutions, human urine, and human plasma utilizing 10(-1) M HCl as the acceptor phase and 10(-1) M NaOH in the donor solution. In addition to preconcentration, LLLME also served as a technique for sample cleanup since large molecules, acidic compounds, and neutral components were not extracted into the acceptor phase. Utilizing diphenhydramine hydrochloride as internal standard, repetitive extractions varied less than 5.2% RSD (n = 6), while the calibration curve for methamphetamine was linear within the range 20 ng/microL to 10 micrograms/mL (r = 0.9983). The detection limit of methamphetamine utilizing LLLME/CE was 5 ng/mL (S/N = 3) in both human urine and plasma.
以甲基苯丙胺作为模型化合物，从2.5 mL pH值调至13的水样（供体溶液）中，通过聚丙烯中空纤维孔内的1-辛醇薄相进行萃取，最终进入中空纤维内25 μL的酸性受体溶液中。经过这种液-液-液微萃取（LLLME）后，通过毛细管区带电泳（CE）对受体溶液进行分析。萃取在简单的一次性装置中进行，每个装置由一个常规的4 mL样品瓶、两根用于引入和收集受体溶液的针以及一段8 cm长的多孔聚丙烯中空纤维组成。同时对5至20个不同样品进行45分钟的萃取，具有较高的样品处理量。使用10⁻¹ M HCl作为受体相，供体溶液中使用10⁻¹ M NaOH，甲基苯丙胺在水标准溶液、人尿液和人血浆中可预富集75倍。除了预富集外，LLLME还作为一种样品净化技术，因为大分子、酸性化合物和中性成分不会被萃取到受体相中。以盐酸苯海拉明作为内标，重复萃取的相对标准偏差（RSD）变化小于5.2%（n = 6），而甲基苯丙胺的校准曲线在20 ng/μL至10 μg/mL范围内呈线性（r = 0.9983）。使用LLLME/CE测定人尿液和血浆中甲基苯丙胺的检测限均为5 ng/mL（S/N = 3）。
