AWWA WQTC71462

Haloacetic acids (HAAs) are among disinfection byproducts that are produced during chlorination of water containing natural organic matter and bromide. Five HAAs are currently regulated in finished drinking water by the U.S. Environmental Protection Agency (USEPA). The methods that are approved for compliance monitoring include USEPA Method 552.1, 552.2, 552.3 and Standard Method 6251B. These methods are fairly challenging and time consuming as each requires an extraction and derivatization procedure, which is followed by gas chromatography (GC) with electron capture detection (ECD) using a procedural calibration technique. Ion chromatography-mass spectrometry (IC-MS/MS) offers a sensitive and selective alternative that does not require sample pretreatment or procedural calibration. Water samples are directly injected into an ion chromatograph coupled to a triple quadrupole mass spectrometer. This method is currently being evaluated by the USEPA at the Office of Ground Water and Drinking Water's laboratory in Cincinnati, Ohio as Method 557. Water samples from three separate sources were used to compare HAA amounts using USEPA 552 and the new method under validation, USEPA 557. Excellent peak resolution and linearity are achieved for analyte concentrations that range between 0.4 µg/L and 100 µg/L in a matrix containing up to 250 mg/L each of chloride and sulfate, and 30 mg/L of nitrate. Using ¹³CClH₂COOH as an internal standard, the detection limit is less than 0.4 µg/L for each of the five regulated HAAs and less than 1 µg/L for the other four. No significant matrix effects are observed in the synthetic matrix, and recoveries of all nine HAAs are greater than 90% for both methods. Using spike recoveries of all nine HAA's, variability between methods was between 70 and 130% for most determinations. Includes tables, figures.