Drinking Water Testing
Home > Speciality Testing > Haloacetic Acids
Haloacetic acids
Determining haloacetic acids in drinking water.
Haloacetic acids are a group of disinfection byproducts that are formed when disinfectants, such as chlorine or chloramine, are used to treat water and react with naturally occurring organic and inorganic matter present in source waters.
Which HAA forms depends on several factors, so HAAs are often tracked and described as groups of individual acidic compounds. As more HAAs are included in one of these groupings, the list of compounds that contain bromide increases:
- HAA5 includes dibromoacetic acid, dichloroacetic acid, monobromoacetic acid, monochloroacetic acid, trichloroacetic acid
Process
A 40-mL volume of sample is adjusted to a pH of 0.5 or less and extracted with 4 mL of either methyl tert-butyl ether (MTBE) or tert-amyl methyl ether (TAME) containing an internal standard. The haloacetic acids that have been partitioned into the organic phase are then converted to their methyl esters by the addition of acidic methanol, followed by heating for 2 hours. The solvent phase containing the methylated haloacetic acids is separated from the acidic methanol by adding 7 mL of a concentrated aqueous sodium sulfate solution. The aqueous phase is discarded. The extract is then neutralized with a saturated solution of sodium bicarbonate, and the solvent layer is removed for analysis.
The target analytes are identified and quantified by capillary column gas chromatography using an electron capture detector (GC/ECD). Analytes are quantified using standard procedural calibration.
©RWA. All rights reserved. Reproduction not permitted.