Immunoassay of Pesticides: An Update

Abstract

Measurement of levels of pesticide residues in foods and crops most often requires extensive cleanup and instrumental techniques such as gas chromatography. Immunoassay measurement techniques, on the other hand, may be used directly on the test portion or require only minimal cleanup. Further refinements of the common antibody–enzyme-based solid-phase assays, such as use of coated magnetic particles, antibody-coated crystals, and continuous-flow devices, have extended the measurement range and applicability of these assays. Likewise, new immunoassays for pesticides have been developed, and existing assays have been refined, optimized, and more completely characterized and validated. In addition to their ability to accurately and reliably measure amounts of residues present in food and crops, immunoassays can be readily used as rapid screening methods for contaminants in field samples. We have previously reviewed much of the work in the area of pesticide immunoassay; this report updates previous information and discusses some new immunoassay techniques.

Linking Solid Phase Extraction and Enzyme‐Linked Immunosorbent Assay to Measure Chlorpyrifos in Fish Tissue

“…Lipids may interfere with the binding of the analyte, which interferes with the immunoassay. Substances from the matrix might bind to antibodies in such a way as to compete with analyte binding (Kaufman 1995). To examine the matrix effect, 3 catfish fillets obtained from different grocery stores were tested to determine if the background was consistent.…”

Interlaboratory validation of an atrazine immunoassay

“…2.0. Although many immunoassays have been developed for research applications (Kaufman & Clower, 1995; Marsden, 1995; Meulenberg et al, 1995; Vanderlann et al, 1988; Van Emon 8c Lopez‐Avila, 1992), only a small number have been submitted for regulatory use. Many of these methods, such as SW (Solid Waste) 846 method 4670, triazine herbicides as atrazine in water (USEPA, 1998), have been proposed under the Resource Conservation and Recovery Act and are not applicable for use under the SDWA.…”

A Survey of Laboratory and Statistical Issues Related to Farmworker Exposure Studies

“…IAs may be very specific for a given chemical, or they may have a great deal of cross-reactivity that can limit their utility for single pesticide identification. This cross-reactivity may allow assessment of exposure to a class of chemically related pesticides ( Kaufman and Clower 1995 ). The LODs for IAs can vary widely; however, many have adequate sensitivity for measuring low-level exposures, but most are targeted at measuring occupational exposures.…”