Urinalysis Drug Tests

Urinalysis Drug Tests

Testing is most frequently performed on small samples of urine,
although hair, saliva, and blood can also be used. Urine samples are
collected by personnel under carefully controlled circumstances to
avoid mismatches resulting in false positives, and to prevent
adulteration of the specimen by the swapping of samples or the
addition of foreign substances. In particular, urine samples heavily
diluted with water can skewer results, and so highly diluted specimens
are routinely rejected. In certain legal cases involving individuals
known to be repeat drug offenders, personnel are usually required to
witness the sample being provided in order to ensure that no
adulteration has taken place.

Samples can be tested at the same site in which they were provided.
More frequently, it is shipped to a large facility that specializes in
mass-testing specimens. Care must be taken in shipping to ensure the
integrity of the specimen, and those that indicate contamination are
not processed. A special tamper-proof seal is routinely placed on
bottles to indicate whether or not this has occurred.

A urinalysis test is then run to indicate the presence of various
chemicals within the sample. This initial procedure is known as the
screening test. A positive result for any of the substances marked for
testing will result in the sample being run for a confirmation test.
In this case, more advanced and expensive processes are used to ensure
the validity of the positive result. A common process used in this
second stage is GC/MS (gas chromatography/mass spectometry) in which
the sample is analyzed at a molecular level for the specific substance
that tested positive in the screening; GC/MS is known to be highly
reliable.
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