Determination of Glyphosate and AMPA

Glyphosate, the most commonly used herbicide in current production, is widely used to control pests in corn and soybean fields. Little is known about the fate of glyphosate after it has entered the soil after spraying, so it – and its degradation products AMPA and glufosinate – have become compounds of interest for study. The USGS has introduced a method to determine the presence of certain pesticides in water using isotope dilution, and more information is available about this process here. 

Glyphosate, the active ingredient in Roundup^®, has been commercially available for four decades as an agricultural pesticide. Millions of pounds are used each year, with little information available on the fate of the pesticide once it has performed its intended task. Analytical methods available for determining the fate of other pesticides were unsuitable for glyphosate analysis, and until fairly recently information was scant.

With millions of pounds of herbicide being used yearly, a method for determining the fate of this material needed to be developed that covered, not only glyphosate itself but also the main breakdown product aminomethylphosphonic acid, more commonly called AMPA. As the herbicide degrades over time after use, AMPA levels provide some measure of information as to the fate of the parent molecule. The USGS developed a method to detect glyphosate and AMPA in the early 2000s; a new method 5-A10 has been put into place that utilizes stable labeled isotopes to further quantitate the levels of these compounds.