Analysis of terbuthylazine in soil samples by two test strip immunoassay formats using reflectance and luminescence detection.

Two different immunoassay (IA) formats for terbuthylazine analysis were developed and optimized using the same monoclonal antibodies. The measuring range for the dipstick IA (using an alkaline phosphatase tracer, a 5-bromo-4-chloroindolylphosphate/nitro blue tetrazolium substrate and a portable reflectometer) was from 3 to 300 microg/kg. The teststrip IA (investigating a horseradish peroxidase tracer, a luminol substrate, and a portable luminometer prototype developed by Immunotek, Moscow, Russia) had a measuring range from 0.05 to 10 microg/kg. From 24 soil samples collected in the Veneto area, Italy, 18 samples contained different amounts of terbuthylazine (but <1 microg/kg atrazine) as was analyzed by gas chromatography with mass selective detection. Eight soil samples (six positive, two negative controls) were analyzed according to the two IA formats. Whereas the dipstick with reflectance detection yielded satisfying results, the test strip IA using luminescence detection has failed so far for soil samples.