Liquid-phase microextraction using hollow fiber membrane for determination of disinfection by-products in water

Abstract

Liquid-phase microextraction (LPME) with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction, preconcentration and determination of trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water and tap water. THMs were directly extracted from 10 mL water sample by LPME using 1-octanol as extracting solvent at 35 °C for 30 min. HAAs were in-situ derivatized in 10 mL water sample by esterification with acidic methanol at 55 °C, followed by headspace extraction and concentration with LPME for 60 min. The proposed methods provided high enrichment factor up to 62 fold. The linearity ranges of both THMs and HAAs with correlation coefficient > 0.9904 were obtained. Relative standard deviations were below 12 %, and the method detection limits (MDL) were at sub µg/L levels, which were lower than previously studied such as headspace, solid-phase microextraction and single-drop microextraction. Moreover, MDL are also lower than the maximum contamination level (MCL) values of WHO, EU and US EPA regulations. Application of these methods to water samples from Chulalongkorn University was performed. The results from survey water samples showed that the concentrations of THMs and HAAs were within the permissible level allowable by WHO, EU and US EPA regulations.