The method of collecting a urine sample for drug screening
April 6, 2010 in Employee Drug Testing Information
The method of collecting a urine sample for drug screening can be important. Some illicit drug users may attempt to substitute another person’s urine, or chemically alter their own specimen. If the urine drug screen is being used for an important decision, such as employment or legal action, procedures to minimize chances of an adulterated or substituted sample may be necessary. These include measuring the temperature or pH of the sample immediately after it is procured, and using tamper-proof containers. Supervised specimen collection may be conducted to ensure that the urine indeed comes from the person being screened.
The most commonly used method for urine drug screening is immunoassay, a rapid and accurate test that uses antibodies embedded on test strips to reveal drug use. Antibodies react only in the presence of very specific substances—in this case, drugs present in urine. When a sufficient concentration of a drug (or drugs) are present, the test strip will indicate which substances have been detected. A control band on each strip confirms that the test was done correctly.
Positive screening results should always be confirmed by a more sensitive method. The most widely accepted corroborative test for all drugs is gas chromatography/mass spectrometry (GC/MS), which can determine the specific substances in the body by recognizing not only the molecular structure of the original compound, but also its metabolite, a chemical created when the drug is metabolized.