Application of automated solid-phase microextraction to determine haloacetonitriles, haloketones, and chloropicrin in Canadian drinking water
An automated headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method was developed to monitor the occurrence of selected haloacetonitriles (HANs), haloketones (HKs), and chloropicrin (CP) in drinking water supplies. The method was rapid with analysis time of 30 min, including extraction and chromatographic run. Chemical ionization (CI) was used to increase the sensitivity of the method for the HKs. SPME fibers with seven different coatings including commercial polyacrylate (PA), carbowax/divinylbenzene (CW/DVB), polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and a novel custom-made polydimethylsiloxane/divinylbenzene-N-vinylpyrrolidone (PDMS/DVB-NVP) were evaluated. The DVB/CAR/PDMS fiber was found more suitable for the range of the analytes and the novel PDMS/DVB-NVP fiber more efficient for the brominated acetonitriles under the experimental conditions. Method detection limits (MDLs) for the chlorinated acetonitriles and CP varied between 2 and 40 ng/L and for the brominated acetonitriles and HKs between 100 and 180 ng/L. Relative standard deviations (RSD %) of measurements were 4–7%. The method was applied in parallel with a liquid–liquid extraction gas chromatography electron capture detection (LLE-GC-ECD) method (EPA Method 551.1) to the analysis of drinking water samples from eight Canadian water treatment and distribution systems. The results generated by the two methods showed good agreement.