Detection and removal of sample matrix effects in agrochemical immunoassays
1996
Skerritt, J.H. | Rani, B.E.A.
With the completion of the initial development of assays for many of the most important agrochemicals, there has been an increased focus on actual applications of agrochemical immunoassays to food and environmental matrices. A major prerequisite to assay utilization has been the need to identify and remove matrix interferences, which may result in: 1. residue-free samples appearing positive, or else samples containing residues appearing negative; or 2. changes in the sensitivity of residue detection, from either or both shifts in the assay absorbance values in the absence of pesticide or in the standard curve. Matrix effects are best detected by analysis of spikes of pesticide standards into a solvent extract of pesticide-free matrix and comparison of this concentration-response curve with that obtained using standards prepared in solvent alone. A number of approaches to the removal of matrix interference is reviewed, with particular reference to examples from the analyses of insecticide residues in plant-derived foods, including grain and fruit products.
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