Determination of Haloacetic Acids and Dalapon in Drinking Water

Haloacetic acids and the pesticide Dalapon determined in drinking water by SPE followed by GC/ECD.

EPA Method 552.1: Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Solid Extraction (GC/ECD), Alltech Application Note ANE004, 1997.

One of the alternatives to chlorine as a drinking water disinfectant, chlorine dioxide, does not produce cancer-causing trihalomethanes (THM) as does chlorine, but does produce haloacetic acids which have their own potential health consequences.

EPA Method 552.1 is used to determine six haloacetic acids (monochloroacetic acid, monobromacetic acid, dichloroacetic acid, trichloroacetic acid, bromochloroacetic acid and dibromoacetic acid) and a pesticide Dalapon. Water samples are passed through a solid phase extraction anion exchange (SPE) tube, in this example, Alltech Ultra Clean SPE Tube Part No. 509700. The haloacetic acids and pesticide adsorbed onto the solid phase, eluted with an acid methanol mixture and methylated with methyl-tert-butyl ether (MTBE). The methylated mixture is extracted with water and the MTBE phase is analyzed by GC/ECD.

Both the AT-1701 (Part No. 13690) and AT-210 (Part No.13800) columns can be used for this determination. An example chromatogram obtained using the AT-1701 column (30m x 0.32mm x 0.25µm) is shown with all of the haloacetic acids and Dalapon compounds separated and identified using the ECD at 260°C. The column temperature was held at 50°C for 1 min and raised to 120°C at 10°C/min and held for 1 min. Around 2ng of each compound was on column. The GC separation took around 16 minutes.