Solid-phase microextraction coupled with gas chromatography-ion trap mass spectrometry for the analysis of haloacetic acids in water

Headspace solid-phase microextraction (SPME) was studied as a possible alte rnative to liquid-liquid extraction for the analysis of haloacetic acids (H AAs) in water. The method involves derivatization of the acids to their eth yl esters using sulphuric acid and ethanol after evaporation, followed by h eadspace SPME with a polydimethylsiloxane fibre and gas chromatography-ion trap mass spectrometry (GC-IT-MS). The derivatization procedure was optimiz ed: maximum sensitivity was obtained with esterification for 10 min at 50 d egrees C in 30 mu l of sulphuric acid and 40 mu l of ethanol. The headspace SPME conditions were also optimized and good sensitivity was obtained at a sampling temperature of 25 degrees C, an absorption time of 10 min, the ad dition of 0.1 g of anhydrous sodium sulfate and a desorption time of 2 min. Good precision (RSD lower than 10%) and detection limits in the ng 1(-1) r ange (from 10 to 200 ng 1(-1)) were obtained for all the compounds. The opt imized procedure was applied to the analysis of HAAs in tap water and the r esults obtained by standard addition agreed with those of EPA method 552.2, whereas discrepancies due to matrix interferences were observed using exte rnal calibration. Consequently, headspace SPME-GC-IT-MS with standard addit ion is recommended for the analysis of these compounds in drinking water. ( C) 1999 Elsevier Science B.V. All rights reserved.