Comparative study of sample preparation techniques coupled to GC for the analysis of halogenated acetic acids (HAAs)
Sadia Waseem1, Md Pauzi Abdullah
1Institute of Chemistry, University of the Punjab, Lahore-Pakistan.
Abstract:
Halogenated acetic acids (HAAs) are one of the most common disinfection by-products formed during chlorination of drinking water. Currently, there are three U.S. Environmental Protection Agency-approved methods for analysis of HAAs in drinking water: U.S. EPA method 552.2, Standard Method 6251, and U.S. EPA method 552.3. The current U.S.EPA-approved HAA analysis methods require tedious and time-consuming liquid-liquid extraction (LLE) and the use of hazardous chemicals. Besides U.S. EPA methods, capillary electrophoresis (CE), liquid chromatography (LC), including ion chromatography (IC), and electrospray ionization mass spectrometry (ESI-MS) have been applied in order to determine the HAAs in portable water with high detection limits. Detection limits required to analyze portable water samples can be regularly achieved only by gas chromatography-electron capture detector (ECD) and ESI-MS. In this study, improved gas chromatography-mass spectrometry (GC-MS) method was able to achieve HAAs analysis at low detection limits. Thus, a safe and rapid method is needed for the micro-determination of HAAs. A method involving solid-phase extraction (SPE) followed by GC-MS was developed to determine the HAAs in tap water. Selectivity, percent recovery, and detection limit studies were carried out on a LC-SAX (quaternary ammonium anion exchanger) SPE. Under optimized conditions, average recoveries for all nine HAAs spiked in drinking water samples ranged from 78.7% to 100%. The relative standard deviation data was found to range from 1.0% to 12.5% based upon five repeat recovery experiments, and estimated detection limit ranging between 0.16-0.009 microg/L was obtained. On this basis, SPE was studied as a possible alternative to LLE for the analysis of HAAs in water. Finally, the performance of the SPE-GC-MS with spiked drinking water samples was tested, and the results were compared with those obtained using LLE-GC-ECD. The method was applied for determination of HAAs in drinking water and water samples.
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