Adulteration is the tampering of a urine specimen
with the intention of altering the test results. The use of
adulterants can cause false negative results in drug tests by either
interfering with the screening test and/ or destroying the drugs
present in the urine. Dilution may also be employed in an attempt to
produce false negative drug test results.
One of the best ways to test for adulteration or
dilution is to determine certain urinary characteristics such as
creatinine, pH, and specific gravity and to detect the presence of
glutaraldehyde, nitrite and oxidants /pyridinium chlorochromate (PCC)
in urine.
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Creatinine
is a waste product of creatine; an amino-acid contained in
muscle tissue and found in urine.
1 A
person may attempt to foil a test by drinking excessive amounts
of water or diuretics such as herbal teas to “flush” the system.
Creatinine and specific gravity are two ways to check for
dilution and flushing, which are the most common mechanisms used
in an attempt to circumvent drug testing. Low creatinine and
specific gravity levels may indicate dilute urine. The absence
of creatinine (<5mg/dl) is indicative of a specimen not
consistent with human urine.
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Specific gravity tests for sample
dilution. The normal range is from 1.003 to 1.030. Values
outside this range may be the result of specimen dilution or
adulteration.
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Nitrite
tests for commonly used commercial adulterants such as Klear or
Whizzies. They work by oxidizing the major
cannabinoid
metabolite THC-COOH.2
Normal urine should contain no trace of nitrite.
Positive results generally indicate the presence of an
adulterant.
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Glutaraldehyde tests
for the presence of an aldehyde. Adulterants such as UrinAid and
Clear Choice contain glutaraldehyde which may cause false
negative screening results by disrupting the enzyme used in some
immunoassay tests.³ Glutaraldehyde is not normally found in
urine; therefore, detection of glutaraldehyde in a urine
specimen is generally an indicator of adulteration.
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pH
tests for the presence of acidic or alkaline adulterants in
urine. Normal pH levels should be in the range of 4.0 to 9.0.
Values outside of this range may indicate the sample has been
altered.
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Oxidants/PCC (Pyridinium Chlorochromate)
tests for the presence of oxidizing agents such as bleach
and hydrogen peroxide. Pyridinium chlorochromate (sold under the
brand name UrineLuck) is a commonly used adulterant.³ Normal
human urine should not contain oxidants or PCC.
