Urine Drug Testing
Urine Drug Testing
Let’s make reference to immunoassays. These tests are usually used to check samples. Very sensitive test such as Gas Chromatography and Mass Spectrometry is used in case if drugs or their metabolites are detected. So we may come to the conclusion that immunoassays work on the principle of antigen-antibody interaction. Antibodies are chosen which will bind selectively to drugs or their metabolites. It’s possible to detect the binding using enzymes, radioisotopes or fluorescent compounds.
EMIT (Enzyme Multiplied Immunoassay Technique) is the cheapest and simplest test. That’s why it’s the most widely used of the immunoassays. It is produced by Syva Laboratories. An enzyme is used to detect drugs or their metabolites. However it is the easiest to fail. It doesn’t always give accurate information giving a 4-34% false positive rate.
Let’s make reference to RIA (Radio Immunoassay) a highly sensitive form of testing. It is manufactured by Roche Diagnostics and it’s mainly used by the military. It is similar to EMIT but less popular than it on account of using a radioactive substances such as iodine instead of an enzyme.
And now some words about FPI (Fluorescence Polarization Immunoassay) which is produced by Abbott Laboratories. It is very sensitive form of testing. The selective binding of antibodies to drugs and their metabolites is marked with the help of fluorescent compounds.
Thin Layer Chromatography
This form of testing is not widely used because it requires the subjective judgement of a technician and requires considerable skill and training. Moreover it gives no quantitive information and only indicates the presence of drugs or their metabolites. But let’s also give our attention to this test. The addition of a solvent is involved to the sample and as a result the drugs and their metabolites travel up a porous strip leaving colour spots behind. Then each different substance travels a specific distance and finally the strip is compared with known standards.
Gas Chromatography and Mass Spectometry
To identify and quantify drugs or their metabolites in the urine specialists use Gas Chromatography and Mass Spectometry because of their accurate results. But unfortunately, the equipment necessary to perform it is rather expensive and as a result this is reflected in the price for testing each sample. These tests are may used as a confirmation test after a positive result on an Immunoassay. There are two steps in this process. From the very beginning Gas Chromatography separates the sample into its constituent parts and after that Mass Spectometry identifies the exact molecular structure of the compounds. Urine drug testing is really the definitive method of establishing the presence of drugs in the urine.
Urine Detection Period