Wu Jingming, Lee Hian Kee
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
J Chromatogr A. 2006 Nov 10;1133(1-2):13-20. doi: 10.1016/j.chroma.2006.08.006. Epub 2006 Aug 22.
Ion-pair dynamic liquid-phase microextraction coupled to injection-port derivatization has been developed for the determination of long-chain fatty acids in water samples by gas chromatography-mass spectrometry (GC-MS). In this procedure, long-chain fatty acids (C(14), C(16) and C(18)) were converted into their ion-pair complexes with tetrabutylammonium hydrogen sulfate and then extracted by organic solvent (1-octanol) impregnated in the hollow fiber. The dynamic nature of the extraction was represented by the repeated movement of the acceptor phase (organic solvent) in the hollow fiber that was controlled by a syringe pump. Ion pairs of fatty acids quantitatively formed butyl esters in the injection-port of the gas chromatography. Several parameters such as injection temperature, purge-off time, organic solvent, ion-pair reagent, pH, agitation speed, extraction time and the syringe pump parameters (plunger speed and dwell time) have been optimized. The limits of detection were in the range 0.0093-0.015 ng mL(-1) (at a signal-to-noise ratio of 3) under GC-MS-selected ion monitoring mode and the relative standard deviations were between 7.7% and 11.5%. The method was successfully applied to measure long-chain fatty acids in real water samples.
已开发出离子对动态液相微萃取结合进样口衍生化方法，用于通过气相色谱 - 质谱联用仪（GC - MS）测定水样中的长链脂肪酸。在此过程中，长链脂肪酸（C(14)、C(16)和C(18)）与硫酸氢四丁铵形成离子对络合物，然后用浸渍在中空纤维中的有机溶剂（1 - 辛醇）进行萃取。萃取的动态过程通过由注射泵控制的中空纤维中接受相（有机溶剂）的重复移动来体现。脂肪酸离子对在气相色谱的进样口中定量形成丁酯。对诸如进样温度、吹扫时间、有机溶剂、离子对试剂、pH值、搅拌速度、萃取时间以及注射泵参数（柱塞速度和停留时间）等多个参数进行了优化。在GC - MS选择离子监测模式下，检测限在0.0093 - 0.015 ng mL(-1)范围内（信噪比为3），相对标准偏差在7.7%至11.5%之间。该方法已成功应用于实际水样中长链脂肪酸的测定。
