| Enzyme multiplied immunoassay technique | |
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| Intervention | |
| MeSH | D017248 |
Enzyme multiplied immunoassay technique, or EMIT, is a common method for screening urine and blood for drugs, both legal or illicit. First introduced by Syva Company in 1973, it is the first homogeneous immunoassay to be widely used commercially.
A mix and read protocol has been developed that is exceptionally simple and rapid. The most widely used applications for EMIT are for therapeutic drug monitoring (serum) and as a primary screen for abused drugs and their metabolites (urine). The US patents covering the major aspects of the method, 3,817,837 and 3,875,011, have expired. While still sold by Siemens Healthcare under its original trade name, EMIT, assay kits with different names that employ the same technology are supplied by other companies. The test is not particularly accurate, especially with regard to test results for cannabis. When the Food and Drug Administration approved EMIT, it did so with the strict provision that positive test results should be confirmed by an alternative testing method.[1]
Contents |
1) Combine a sample containing an unknown concentration of antigen (Ag) & a solution containing a known concentration of antibody against the Ag (Ab).
2) Allow binding of Ag & Ab (incubation #1).
3) Add a known concentration of prepared Ag-enzyme conjugate.
4) Allow binding of Ag-enzyme conjugate with any remaining unbound Ab in solution (incubation #2).
The conjugate is constitutionally active; binding to any unbound Ab will render it inactive.
5) Add enzyme substrate.
6) Measure enzyme activity.
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