Immunoassay for pesticide analysis

Hennion M.-C. (1998). Applications and validation of immunoassays for pesticides analysis. 

Lopez, M.A., E. Donunguez, and F. Ortega (1999). Flow-based immunoassay for pesticide analysis, using fluorimetric detection. Biomed. Chromatogr., 13 121-122. 

Emphasis will be placed on the justification of and the resources required for the successful incorporation of immunochemical technology into an existing analytical laboratory. Special attention will be given to aspects of immunochemical and related technology not covered in other recent reviews. Present use of immunoassay for pesticide analysis will be described and future potential applications and problems will be discussed. 

V. Lopez-Avila, C. Charan, and J. van Emon, Supercritical fluid extraction-enzyme-linked immunosorbent assay applications for determination of pesticides in soil and food, in Immunoassays for Residue Analysis Food Safety (R.C. Beier and L.H. Stanker eds), ACS Symposium Series 621, American Chemical Society, Washington (1996). 

JM Van Emon, JN Seiber, BD Hammock. Immunoassay techniques for pesticide analysis. In J Sherma, ed. Advanced Analytical Techniques. New York Academic Press, 1989, pp 217-263. 

Nugent, P. (1992). Enzyme-linked competitive immunoassay. In T. Cairns and J. Sherma, eds., Emerging Strategies for Pesticide Analysis. Boca Raton, FL CRC Press, Inc., pp. 247-258... 

Hennion, M.-C. and D. Barcelo. 1998. Strengths and limitations of immunoassays for effective and efficient use for pesticide analysis in water samples A review. Anal. Chim. Acta 362 3-34. 

Van Emon, J.M. Seiber, J. N. and Hammock, B. D. Immunoassay Techniques for Pesticide Analysis. In Analytical Methods for Pesticides and Plant Growth Regulators. Vol XVII. 1989, pp 217-263. 

A. Dankwardt, B. Hock, Enzyme Immunoassays for the Analysis of Pesticides in Water and Food, /. Food Technol. BiotechnoL, 35,165—174 (1997). 

P. Nugent, Enzyme-linked Competitive Immunoassay , in Emerging Strategies for Pesticide Analysis, eds. T. Cairns, J. Sherma, CRC Press, Boca Raton, FL, 247-258,1992. 

This assay was validated In a field study which examined assay performance and compared data obtained on the same samples by GC analysis. These data have been published (12), and to our knowledge, Is the first study of Its kind which addresses procedural error and data handling for real world samples In Immunoassay for pesticides. Thus, It seems appropriate to reiterate some of the salient points here. 

In recent years, immunoassays for pesticides, phytopharmaceuticals, and industrial pollutants (polychlorinated biphenyls, dioxins, etc.) have become accepted as methods that complement traditional analytical procedures also in the field of food analysis (including drinking water). In the case of pesticides, both quantitative and semiquantitative kits are available. Crossreactivity may occur - although with different efficiency - between an antibody raised against a protein conjugate of a given compound, and structurally... 

The ICMs used for pesticide analysis include immimoassays (lAs) and the use of antibodies for sample preparation (e.g., for SPE and the cleanup of samples) [153], detection in flow-injection analysis, and biosensors. The earliest ICMs to be developed for pesticides analysis were lAs. There are various t) es of lAs, but the most frequently used in this context is the enzyme-linked immunosorbent assay (ELISA) [185]. ELISA is a heterogeneous assay because the antibodies or antigens are immobilized on a solid phase. Table 18.3 lists selected ELISA methods for the determination of pesticides in water samples [186-190]. Bjamason et al. have proposed an enzyme flow immunoassay (EFIA) using a protein G column for the determination of triazine herbicides in surface and wastewaters with a linear range between 0.1 and 10 pg/L [191]. 

The development of sensitive and inexpensive immunoassays for low molecular weight pesticides has been an important trend in environmental and analytical sciences during the past two decades. 0.27-29 jq design an immunoassay for a pesticide, one can rely on the immunoassay literature for agrochemicals, " but many of the innovations in clinical immunoanalysis are also directly applicable to environmental analysis. - Conversely, the exquisite sensitivity required and difficult matrices present for many environmental immunoassay applications have forced the development of technologies that are also useful in clinical immunoassay applications. In the following discussion we will describe widely accepted procedures for the development of pesticide immunoassays. 

For pesticide residue immunoassays, matrices may include surface or groundwater, soil, sediment and plant or animal tissue or fluids. Aqueous samples may not require preparation prior to analysis, other than concentration. For other matrices, extractions or other cleanup steps are needed and these steps require the integration of the extracting solvent with the immunoassay. When solvent extraction is required, solvent effects on the assay are determined during assay optimization. Another option is to extract in the desired solvent, then conduct a solvent exchange into a more miscible solvent. Immunoassays perform best with water-miscible solvents when solvent concentrations are below 20%. Our experience has been that nearly every matrix requires a complete validation. Various soil types and even urine samples from different animals within a species may cause enough variation that validation in only a few samples is not sufficient. 

Pesticides, including insecticides, herbicides, and fungicides, are widely used in agriculture, and the potential for these residues to accumulate in food has led to concern for human safety. Pesticide residues may enter food animals from environmental sources or from treated or contaminated feeds. Immunoassay development for pesticides has had major impacts for pesticide registrations, analysis of residues in foods, monitoring environmental contamination, determination of occupational exposure, and integration of pest management. 

The use of immunoassays for the determination of pesticides and veterinary medicines in food animals has increased since the early 1990s. The advantages of simple analysis, quick results, and high throughput make immunoassays a powerful technique for problematic matrices commonly encountered in animal agriculture. Careful development and validation are required to obtain accurate results, however. This review has demonstrated that most immunochemical techniques have been designed for use with milk samples, but a number of applications have also been developed for liver and muscle samples. The development of immunoassay techniques for residue analysis in eggs has clearly not been pursued to the extent of other edible tissues. 

The application of immunoassays to the determination of various urea pesticides have been reported (181,182), and this technique has a great potential for residue analysis by using rapid, simple, and cost-effective tests (183,184). 

Muldoon, M.T., R-N. Huang, C.J. Hapeman, G.F. Fries, M.C. Ma, and J.O. Nelson (1994). Hapten synthesis and immunoassay development for the analysis of chlorodiamino-s-triazine in treated pesticide waste and rinsate. J. Agric. Food Chem., 42 747-755. 

Several qualitative and quantitative immunochemical methods and their application to the analysis of environmental samples have been described for OP insecticides, a family that includes widely used pesticides such as azinphos-ethyl/methyl, dichlorvos, fenitrothion or fenthion, malathion, mevinphos, and parathion. Mercader and Montoya202 produced monoclonal antibodies against azinphos-methyl and developed an ELISA that was used for the analysis of water samples from different sources, reaching detectability levels near 0.05 pg I. Watanabe et al.203 reported the production of polyclonal antibodies and ELISA procedures to analyze fenitrothion in river, tap, and mineral water (LOD = 0.3 pg L ). Banks et al.204 produced polyclonal antibodies against dichlorvos, an organophosphate insecticide used for stored grain, which also cross-reacts with fenitrothion. Nishi et al.205 reported the first immunoassay for malathion. Residues of this insecticide have... 

The expense of an analytical procedure depends upon much more than the cost of the final analysis. Much of the expense of an assay is related to sample preparation, and for many applications immunoassays have tremendously reduced the time needed for sample preparation. Another consideration is the amount of time needed for the development of an assay. The additional expertise which must be developed in an analytical laboratory before immunoassays can be used with confidence may seem formidable, and waiting for an animal to develop antibodies may lead to unacceptable delays in assay development. On the other hand, once a usable antibody titer is obtained, the development of a workable assay is usually straightforward. It is also likely, if immunoassays become accepted for some aspects of pesticide analysis, immunoassay kits or at least critical reagents will become commercially available. Such kits already exist for many pharmaceutical products and hormones, and numerous companies will supply antibodies to a user supplied hapten on a contract basis (83). 

The enzyme-linked Immunosorbent assay (ELISA) is a rapid Immunochemical procedure which can be used for trace analysis. We have applied the procedure to paraquat and other compounds difficult to analyze by the more classical methods. The Immunoassay for paraquat shows the practicality of the method for fortified and actual residue samples, and Is being compared with a gas chromatography procedure. Our work with the ELISA Illustrates that the Immunochemical technology can be used to solve problems encountered In pesticide residue analysis. 

Antibodies have been raised against representative compounds from the major classes of pesticides. Although the ELISA will be useful for individual analysis of a wide variety of compounds, if one needed to analyze several different compounds simultaneously in one matrix immunoassay may not be the method of choice, due to the large amount of controls and standards needed. However, it could be successfully used for the rapid screening of a large number of samples for the presence of specific types of pesticides and for confirmatory tests (Ji). The work reported here with paraquat,... 

The application area of LC-MS is rapidly growing. LC-MS is now regularly used for the analysis of many different types of compound drugs and metabolites, herbicides-pesticides and metabolites, surfactants, dyes, saccharides, lipids-phospholipids, steroids, and many others. In our opinion, the area that profits more from the development of LC-MS is bioanalysis natural products, proteins, peptides, nucleosides, and metabolic studies. Despite the current trends toward immunoassays-biospecific assays and capillary electrophoresis, LC-MS is an extremely powerful analytical technique that is considered complementary to the above mentioned, rather than competitive. 

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