CADDIS Volume 2: Sources, Stressors & Responses
Ways to Measure Herbicides
Herbicides and their metabolites can be measured in groundwater and surface water by gas chromatography (GC), mass spectrometry (MS), high performance liquid chromatography with diode-array detection (HPLC/DAD), liquid chromatography (LC), solid-phase extraction (SPE) or enzyme-linked immunosorbent assay (ELISA) (Scribner et al. 2000). Because there isn't a standard method for detecting all herbicides, measurements can be difficult, expensive, and time-consuming. Herbicide metabolites can have toxicity similar to that of the parent herbicide and are often found in higher concentrations (USGS 2010). Presently metabolites of triazines, chloroacetanilides, phenyl ureas, and the phosphanoglycine glyphosate have been measured (Scribner et al. 2000, USGS 2010). Different herbicides and metabolites are measurable using different techniques, and the proper technique must be matched with the metabolite of interest. The USGS Toxic Substances Hydrology Program provides guidance, lab methods, field methods, and literature related to detecting herbicides in ground and surface water.