Zhao Limian, Zhu Lingyan, Lee Hian Kee
Department of Chemistry, National University of Singapore, Singapore.
J Chromatogr A. 2002 Jul 19;963(1-2):239-48. doi: 10.1016/s0021-9673(02)00544-7.
Liquid-liquid-liquid microextraction (LLLME) with hollow fibers in high-performance liquid chromatography (HPLC) has been applied as a rapid and sensitive quantitative method for the detection of four aromatic amines (3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline) in environmental water samples. The preconcentration procedure was induced by the pH difference inside and outside the hollow fiber. The target compounds were extracted from 4-ml aqueous sample (donor solution, pH approximately 13) through a microfilm of organic solvent (di-n-hexyl ether), immobilized in the pores of a hollow fiber (1.5 cm length x 0.6 mm I.D.), and finally into 4 microl of acid acceptor solution inside the fiber. After a prescribed period of time, the acceptor solution inside the fiber was withdrawn into the microsyringe and directly injected into the HPLC system for analysis. Factors relevant to the extraction procedure were studied. Up to 500-fold enrichment of analytes could be obtained under the optimized conditions (donor solution: 0.1 M sodium hydroxide solution with 20% sodium chloride and 2% acetone; organic phase: di-n-hexyl ether; acceptor solution: 0.5 M hydrochloric acid and 500 mM 18-crown-6 ether; extraction time of 30 min; stirring at 1,000 rev./min). The procedure also served as a sample clean-up step. The influence of humic acid on the extraction efficiency was also investigated, and more than 85% relative recoveries of the analytes at two different concentrations (20 and 100 microg/l) were achieved at various concentration of humic acid. This technique is a low cost, simple and fast approach to the analysis of polar compounds in aqueous samples.
高效液相色谱（HPLC）中采用中空纤维的液-液-液微萃取（LLLME）已被用作一种快速灵敏的定量方法，用于检测环境水样中的四种芳香胺（3-硝基苯胺、4-氯苯胺、4-溴苯胺和3,4-二氯苯胺）。预富集过程由中空纤维内外的pH差异引发。目标化合物从4毫升水样（供体溶液，pH约为13）中通过有机溶剂（二正己醚）微膜萃取出来，该微膜固定在中空纤维（长度1.5厘米×内径0.6毫米）的孔隙中，最终进入纤维内部4微升的酸接受溶液中。经过规定时间后，将纤维内部的接受溶液吸入微量注射器，直接注入HPLC系统进行分析。研究了与萃取过程相关的因素。在优化条件下（供体溶液：含20%氯化钠和2%丙酮的0.1 M氢氧化钠溶液；有机相：二正己醚；接受溶液：0.5 M盐酸和500 mM 18-冠-6醚；萃取时间30分钟；以1000转/分钟搅拌），分析物可实现高达500倍的富集。该方法还可作为样品净化步骤。还研究了腐殖酸对萃取效率的影响，在不同浓度腐殖酸存在下，两种不同浓度（20和100微克/升）的分析物相对回收率均超过85%。该技术是一种低成本、简单快速的分析水样中极性化合物的方法。
