Immunoassay technology offers many advantages over conventional analytical methods for pesticide analysis in the field, and in this study enzyme‐linked immunosorbent assay (ELISA) was applied to the analysis of s‐triazine herbicides in pesticide waste and rinsate mixtures. This sample type usually contains a mixture of pesticide active ingredients, formulating agents, fertilizers and debris. Therefore it was necessary to study the effects of these potential matrix components on the ELISA. This was done by evaluating ELISA standard curve parameters in the presence of matrix components. The assay tolerated fertilizer concentrations up to 1% (w/v) in the sample and had a wide pH range (2–9). MgCl2produced effects at 0.009% (w/v) which could result in a false negative result, but all other matrix effects implied false positive results and overestimates of analyte concentration. Ionic surfactants affected the assay above 0.156% (v/v). Non‐ionic surfactants had little effect on the assay, but commercial agricultural formulations interfered with it above 0.156% (v/v). A rapid solid‐phase extraction method for s‐triazine herbicides was tested on actual rinsate samples and improved assay precision.