Introduction and Background

Long term use of the herbicide atrazine in Wisconsin has resulted in the contamination of
Wisconsin's groundwater in many areas of the state. While atrazine has been restricted or
banned in certain areas of the state that have been shown to be susceptible to groundwater
contamination, it is still being used in other areas as an effective means to control weeds
in corn crops. While the detection of atrazine led to the original environmental concerns,
it has also been recognized that degradation products or metabolites of atrazine, which
can be just as toxic as the parent compound, can exist for a long time before they are
further degraded or reduced in concentration by dilution.
In Wisconsin atrazine and atrazine metabolites are regulated in combination. The
maximum contamination limit (MCL) for the sum of atrazine and atrazine metabolites is
3.0 parts per billion (micrograms per liter). While the standard method for detection of
the compounds is conventional gas chromatography, a much lower cost atrazine enzyme
linked immunosorbent assay (ELISA) has been used at the Wisconsin State Laboratory of
Hygiene (WSLH) for many years to screen water samples for the presence of atrazine.
The atrazine ELISA used at the WSLH primarily detects the parent compound, but has
some cross reactivity to some atrazine metabolites, mainly desethyl-atrazine. Of the
known atrazine metabolites that can exist in groundwater, diaminoatrazine is of the most
interest because of its suspected toxicity. However, diaminoatrazine is a relatively
difficult, and thus expensive, analyte to measure using conventional chromatographic
techniques. Consequently a new diaminoatrazine ELISA test has recently been
The work described in this report provides an evaluation of the diaminoatrazine ELISA to
determine its value for use as a routine groundwater-monitoring tool. In this study, 74
water samples, mostly groundwater, were analyzed for atrazine and atrazine metabolites
using conventional gas chromatographic methods at the Wisconsin Department of
Agriculture Trade and Consumer Protection's (WDATCP) pesticide laboratory. Aliquots
of those 74 samples were also analyzed using both the atrazine and diaminoatrazine
ELISA at the WSLH. An evaluation of the ELISA results, relative to the conventional
chromatographic measurements, was made.
Materials and Methods
The majority of the water samples were collected from groundwater wells that WDATCP
routinely monitors due to the wells' history of atrazine and atrazine metabolite
contamination. Additionally groundwater samples from random wells that tested negative
for atrazine by ELISA were also analyzed for diaminoatrazine, as were a few surface
water samples.