Chapter 4
Factors Influencing the Specificity and Sensitivity of Triazine Immunoassays 1
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Timothy S. Lawruk , Charles S. Hottenstein , James R. Fleeker , Fernando M . Rubio , and David P. Herzog Downloaded by STANFORD UNIV GREEN LIBR on October 10, 2012 | http://pubs.acs.org Publication Date: June 21, 1996 | doi: 10.1021/bk-1996-0630.ch004
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Ohmicron Environmental Diagnostics, 375 Pheasant Run, Newtown, PA 18940 Biochemistry Department, North Dakota State University, P.O. Box 55116, Fargo, ND 58105
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The use of immunochemical methods to assess the quality of surface and ground water has become a valuable complement to conventional methods such as GC and HPLC. Immunoassays for water analysis have proven to be rapid, sensitive and convenient, allowing a large number of samples to be screened without prior sample preparation. Magnetic particle-based immunoassays for triazines have been developed to offer a wide range of specificities and sensitivities to both parent compounds and metabolites. By varying the design of the triazine immunogen and enzyme conjugate hapten, immunoassay specificity can be manipulated to detect a wide range of triazines or be specific to only the parent compound. The least detectable concentration of each triazine can also be decreased by modification of these components. The development strategies for triazine immunoassays including atrazine, simazine and cyanazine will be discussed. The worldwide use of the 1,3,5-triazine or s-triazine herbicides as pre- and postemergence herbicides for the control of broad-leaved weeds on corn, sorghum and fruit orchards has necessitated that these compounds and their metabolites be monitored in the environment. For example, atrazine residues are often detected in environmental water samples as a result of spills, spraying, and agricultural run-off (7-3). The widespread application, stability and solubility of the triazines in water allow them to leach from soil and be relatively persistent environmental contaminants (4). The use of enzyme immunoassay to screen water samples for the presence of triazine herbicides, in particular atrazine, simazine and cyanazine, has been widely applied (7-3, 5-77). Immunoassays provide the analytical chemist with a cost-effective, sensitive, rapid and reliable method for both laboratory and field analyses (#). These immunoassay methods have been developed using a variety of 0097-6156/96/0630-0043$15.00/0 © 1996 American Chemical Society In Herbicide Metabolites in Surface Water and Groundwater; Meyer, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1996.
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HERBICIDE METABOLITES IN SURFACE WATER AND GROUNDWATER
solid-phases including antibody adsorbed to microtiter plate wells, polystyrene test tubes and antibody covalently coupled to magnetic particles. The magnetic particle-based triazine immunoassays described herein are used to evaluate the effects of immunogen and enzyme conjugate hapten design on the assay sensitivity and specificity.
Downloaded by STANFORD UNIV GREEN LIBR on October 10, 2012 | http://pubs.acs.org Publication Date: June 21, 1996 | doi: 10.1021/bk-1996-0630.ch004
Materials and Methods Antibody Production. The preparation of the immunogen is a critical step in the development of an immunoassay. Since triazines are small molecules (10,000
22.4 0.3 0.5 10,000
185 113 97 32.4 14.7 13.1 4.6 100 >100
41.6 23.8 21.3 5.8 100
27.2 100 >100 >100 >100
