Determination of carbofuran in fish and corn leaves by two types of commercial immunoassays

We evaluated two commercially available immunoassay kits for the detection of carbofuran in fish and corn leaves. We observed strong matrix interference or inhibition due to the extraction solvent. This interference was corrected by either diluting or decolorizing and diluting the extract. The coefficient of variation of the recovery ranged from 3.9 - 11.0% for the coated tubes compared to 1.3 - 3.9% for magnetic particles bases kits. We detected carbofuran in the range of 0.33 - 0.51 ng/g in fish and 0.75 2.20 ng/g in corn leaf. The ELISA detection limits were 0.5 ng/g in corn leaf and 0.3 ng/g in fish fillet. The samples, which were positive for carbofuran (by kits) were found to contain carbofuran (by GLC) with a good coefficient of correlation (r 2 = 0.997). These results showed that ELISA can be used for the determination of pesticides in the environment, but observed cross reactivity with the metabolites may interfere with the detection of the parent compound and hinder the detection. The possibility of false positive or false negative detection may require the use of chromatography as confirmation technique. In any case, ELISA is advantageous to developing countries because of the low cost of material acquisition.