In situ derivatization and hollow fiber membrane microextraction for gas chromatographic determination of haloacetic acids in water

Abstract

An alternative method for gas chromatographic determination of haloacetic acids (HAAs) in water using direct derivatization followed by hollow fiber membrane liquid-phase microextraction (HF-LPME) has been developed. The method has improved the sample preparation step according to the conventional US EPA Method 552.2 by combining the derivatization and the extraction into one step prior to determination by gas chromatography electron captured detector (GC-ECD). The HAAs were derivatized with acidic methanol into their methyl esters and simultaneously extracted with supported liquid hollow fiber membrane in headspace mode. The derivatization was attempted directly in water sample without sample evaporation. The HF-LPME was performed using 1-octanol as the extracting solvent at 55°C for 60min with 20% Na2SO4. The linear calibration curves were observed for the concentrations ranging from 1 to 300μgL−1 with the correlation coefficients (R2) being greater than 0.99. The method detection limits of most analytes were below 1μgL−1 except DCAA and MCAA that were 2 and 18μgL−1, respectively. The recoveries from spiked concentration ranged from 97 to 109% with %R.S.D. less than 12%. The method was applied for determination of HAAs in drinking water and tap water samples. The method offers an easy one step high sample throughput sample preparation for gas chromatographic determination of haloacetic acids as well as other contaminants in water.