Cereal Chem. 70:748-752   |  VIEW ARTICLE

Analysis of the Grain-Protectant Pesticides Chlorpyrifos-Methyl and Methoprene with a 15-Min Immunoassay for Field or Elevator Use.

S. L. Edward, A. S. Hill, P. Ashworth, J. Matt, and J. H. Skerritt. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

Antibody-based tests for field use have been developed to enable semiquantitative analysis of two grain protectants, chlorpyrifos-methyl and methoprene. In these tests, a pesticide-containing methanol extract of the grain sample and an enzyme-labeled analog of the pesticide are separately added dropwise to antibody- precoated test tubes containing a aqueous diluent. After a brief incubation period, the tubes are rinsed with tap water, and a substrate (chromogen) for the enzyme is added. The color developed is stabilized by acidification. The test result is read either by eye or in a portable field photometer. Pesticide could be extracted efficiently by blending either whole or ground grain for 1 min using a commercial blender or for 2 min using a probe homogenizer. The overall test time is under 15 min. The assays were sensitive to 0.05 ppm of residue in grain. Also, the results correlated well with those obtained using either laboratory immunoassay or chromatographic methods.