Chlorinated phenoxyacid herbicides, and other organic acids are used extensively for weed control. Esters and salts of 2,4-D and silvex have been used as aquatic herbicides in lakes, streams, and irrigation canals. Phenoxy acid herbicides can be toxic even at low concentrations. For example, the 96 h, TL_m for silvex is 2.4 mg/L for bluegills (1) . These reasons make apparent the need for a standard test method for such compounds in water.

1.1 This test method covers a gas chromatographic procedure for the quantitative determination of selected chlorinated acids and other acidic herbicides in water. Similar chemicals may also be determined by this test method, but it is the user's responsibility to verify the applicability of this test method to any compounds not listed in this scope. The acid form of the following compounds were interlaboratory tested using this test method, and the results were found acceptable: