Trace-Level Detection of Atrazine Using Immuno-Chemiluminescence: Dipstick and Automated Flow Injection Analyses Formats.

A sensitive chemiluminescence (CL)-based
immunoassay technique based on both dipstick
and flow injection analytical formats is reported for
the detection of atrazine. In the dipstick-based
immunoassay technique, antibody (anti-atrazine)
was first immobilized on the nitrocellulose
membranes. The dipstick was then treated with
atrazine and atrazine-horseradish peroxidase
conjugate (atra-HRP) to facilitate the competitive
binding. The dipstick was further treated with
urea-hydrogen peroxide (U-H2O2) and luminol to
generate photons. The number of photons
generated was inversely proportional to the
atrazine concentration. In the flow injection
analysis (FIA) format, the antibody was
immobilized on protein-A sepharose matrix and
packed in a glass capillary column, which
functioned as an immunoreactor. Competitive
binding of antigen and antibody occurred. The CL
signals generated during the biochemical
reactions were correlated with atrazine
concentrations in the analytical samples. By using
dipstick technique, it was possible to detect
atrazine concentration down to 0.1 ng/mL; with the
FIA format, the detection of atrazine was down
to 0.01 ng/mL.