We perform a variety
of pesticide analyses,
many of which are not performed by other labs. In addition to the methods
found in the EPA manuals for air, water, and soil, FDA has published the Pesticide
Analytical Manual (PAM) for residues on crops, AOAC has methods for processed
foods, NIOSH and OSHA have published methods for air, and even USP has methods
for pesticides in products used in drugs.
Some
methods cover many individual pesticides which fit in a particular analytical
class, such as organochlorine (OC) or organophosphorus (OP) pesticides. Some,
such as glyphosate, require separate methods because of their unique chemical
properties. Glyphosate [N-(phosphonomethyl)- glycine] is better known as the
product Round-Up® made by Monsanto. It is a post-emergence herbicide which
degrades rapidly in the environment. After using it to kill weeds, the area
can be planted again in just a few days. Because of glyphosate's polar nature
and other chemical properties, most current analytical methods use ion chromatography
to separate the analyte from its matrix and interferences. Since it does not
have a chromophore for detection, the column eluant after separation is mixed
with hypochlorite which oxidizes glyphosate to glycine, then mixed with o-phthalaldehyde
and 2-mercaptoethanol to form a fluorescent derivative of the primary amine
group. In this way both glyphosate and its degradation product aminomethyl-
phosphonic acid (AMPA) are detected by fluorescence to provide a very sensitive
and specific analysis. This is only one example of the many pesticides which
require special equipment and chemistry for determination.
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