Enzyme Multiplied Immunoassay Technology (EMIT)

Last Updated: July 15, 2018

Definition - What does Enzyme Multiplied Immunoassay Technology (EMIT) mean?

Enzyme multiplied immunoassay technology (EMIT) is a technology employed for the bioanalysis of substances. Immunoassay tests using EMIT are often used for workplace drug screening. An EMIT test utilizes visible spectroscopy to measure the presence of certain chemicals or molecules in a substance by evaluating the interaction of those chemicals with specific antibodies or antigens. Enzymes are used as a reagent to demonstrate the concentration of each targeted substance visibly. While the technology involves multiple biochemical actions and reactions, the actual analysis takes place in just a few minutes.

EMIT testing is also inexpensive. Thus, EMIT testing is a popular choice for conducting workplace drug screening. A positive result from an EMIT test will indicate that the test subject has been exposed to the tested drugs, but will not indicate the exact measure of drugs in his or her system. In most instances, when an EMIT test reveals possible drug use the sample will then be followed by a more detailed confirmation test.

WorkplaceTesting explains Enzyme Multiplied Immunoassay Technology (EMIT)

The term "assay" refers to a test or analysis. Immunoassay technology is used to detect the presence of a molecule in substance, called the "analyte," by measuring its interaction with an antibody or antigen. In most instances, the analyte is a protein, the antigen, present in the test sample that reacts with an anti-analyte antibody--the antibody that specifically targets the molecule being measured. Because the interaction between antigen and antibody is an immune response, this analysis is referred to as an "immunoassay."

For drug testing, a urine or other fluid sample is mixed with the antibody containing solution and allowed to incubate. For EMIT drug tests, this incubation takes place in just minutes and at a microscopic level. Next, a fixed amount of a solution containing the enzyme-linked drug is added. Again, there is a brief incubation period. At this point, each antibody in the test solution will either be joined to a drug molecule, the analyte, or an enzyme-bound drug molecule. This testing model is referred to as "competitive” because the enzyme-linked drug molecules are competing for antibodies with the drugs present in the sample. Finally, a substrate is added. The substrate is a solution that will interact with any enzyme-linked drug molecules that are not bound to an antibody.

The rate at which this reaction between enzymes and substrate takes place is used to measure the amount of drugs present in the test sample through visible spectroscopy. A higher rate of reaction indicates a higher concentration of drugs in a sample, as this leaves more enzymes free to react with the substrate.

While this form of testing is fast and cost-effective, it is not considered as accurate as the more sophisticated enzyme-linked immunosorbent assay (ELISA) or gas chromography mass spectrometry (GC-MS) tests.

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