Enzyme-linked time-resolved immunoassay

Fig. 11. Detection principle of enzyme-linked time-resolved immunoassay.

Data are expressed as percentages of users for each assay. Abbreviations ELISA, enzyme-linked immunosorbent assay EIA, electroimmunoassay RIA, radioimmunoassay TIA, turbidimetric immunoassay. Delfia, time resolved immunofluorescence assay. 

Reimer, G.J., S.J. Gee, and B.D. Hammock (1998). Comparison of a time-resolved fluorescence immunoassay and an enzyme-linked immunosorbent assay for the analysis of atrazine in water. J. Agric. Food Chem., 46 3353-3358. 

Laboratory testing for ricin is limited, especially for inhalational exposures. The two common methods that can detect ricin in blood or other body fluids are the radioimmunoassay and the enzyme-linked immunosorbent assay (ELISA). Because ricin binds quickly and the body metabolizes it efficiently before excretion, the length of time necessary for these tests limits their usefulness for inhalation exposures (35). Besides testing body fluids, the CDC and member LRN state public health laboratories have a time-resolved fluorescence immunoassay that can test preparations of suspected ricin-containing substances and environmental specimens for the presence of ricin (40). 

In heterogeneous immunoassays in batch format the problem of background fluorescence is reduced by separating the analyte from other fluorescent species present in the sample matrix. The use of enzymes with fluorogenic substrates in fluorescence enzyme-linked immunosorbent assays (F-ELISA) and Eu(in)-chelates in time-resolved fluoroimmunoassay (TRFIA) permits to achieve very low LODs for pesticides (e.g., between 0.023-0.3 and 0.05-0.4pgl for F-ELISA and TRFIA, respectively). 

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