July 20th, 2010
We all know there are different types of tests, but what are they and how do they work?
Most common is an “Immunoassay” testing – it requires the least amount of money a company needs to spend on employee drug testing.
How does it work:
Immunoassay is a screening test which gives a positive or negative result. The sensitivity of this test is pretty high. The toxins present in a sample bind with anti-bodies that are created specifically for this kind of testing. The anti-bodies are created by injecting toxins (drugs) into animals like rabbits or sheep. Their immune system produces anti-bodies against any specific toxin; later they are extracted and purified in laboratories so they can be used further in drug screening. When a sample (urine or hair) is combined with these chemical agents, drug metabolites that are present in the sample bind with the anti-bodies thus making a test result positive. If there are no drugs present in a sample, there is no reaction and test comes up negative.
There are different types of Immunoassay screens: Enzyme- and Radio-immunoassays.
The first one is based on extracting enzymes from animals’ blood: when an animal is injected with specific drug (or drug metabolite) there are certain antigens that are produced in the blood that bind with that specific drug. After extracting those antigens, there are created into enzymes that are later used to detect drugs in a sample. The degree of reaction between enzymes and drugs metabolites is proportional to the amount of drugs presented in the sample.
Radioimmunoassay is a similar test that uses radioactive isotopes to detect and measure results of a drug screen.
Normally, samples that tested positive need to be confirmed by more precise tests.
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