The drug test types reviewed in the following article focus on tests that deliver a quantitative result. Those are the tests that give an employer the most valuable information. The following article does not touch on tests that make use of thin layer chromatography.
During that test, the tested substance moves over a solid. The distance of that movement is then compared to the distance moved by a standard. Thin chromatography allows the employer to learn whether or not some drug is in an employee’s system, but it does not reveal exactly how much of that drug is in his or her system. Drug testing requires the possession of a testable substance. That substance should come from a part of the body that is known to hold the drug of interest. A hair drug test can uncover evidence of drug use in the past, as well as recent drug use. Any drug metabolite in the blood will eventually travel to the head, where it has chance to remain in the hair shaft.
Yet a drug test does not always seek to uncover proof of drug use in the past. For that reason, the hair drug test is not the most favored of the various drug test types. Asked to choose one type of drug test, an employer usually selects the urine drug test. That is the least expensive type of drug test.
The savings that come from the decision to use a urine drug test reduce the ability of the employer to feel confident about the test results. The blood test is the most sensitive drug test. Unfortunately, it is also the most expensive type of drug test.
The hair drug test, the blood drug test and the urine drug test all demand a bit of pre-planning on the part of the employer. Those three tests need to take place at a scheduled time. The saliva drug test can be a spur-of-the-moment test. The can saliva offer proof that an employee has recently used alcohol, marijuana, meth or cocaine.
A drug test can be categorized according to the substance that is tested. A list of drug test types can also offer details on the methodology used in the testing process. An initial drug test is usually an immunoassay. The test kit has been designed to facilitate the binding of antibodies and a drug (or metabolites of that drug).
The cheapest type of immunoassay makes use of enzymes. It is called the enzyme multiplied technique. While simple and cheap, that type of test can not be counted on to deliver reliable results.
The military has the resources for performance of radioimmunoassay techniques. The reading from an immunoassay is taken by a machine that can detect radiation. A radioisotope competes with the drug, as a substance that can bind to a particular antibody. Fluorescence polarization forms the basis for the most frequently used of the immunoassay techniques. When a drug test includes use of fluorescence polarization, then selected antibodies display their affinity for a drug, or its metabolites.
If any of the above-mentioned drug test types yield a positive result, an employer normally calls for a confirmatory finding. The confirmatory test is done using gas chromatography and mass spectrometry. The gas chromatograph separates the components in the tested substance. The spectroscopy looks for tell-tale signs that a drug of interest (or its metabolite) is present in any of those separate components.