| Instructions For
THC Marijuana Test Cassette
|One Step THC Cassette Test Kit For Urine
(Revised May 28th, 2002)
The one step THC (Tetrahydrocannabinol) test is a simple one step immunochromatographic
assay for the rapid, qualitative detection of THC and its metabolites 11-nor-
9-tetrahydrocannabinol-9-carboxylic acid in urine. The cutoff of the test
is 50 ng/ml of THC (11-nor-9-tetrahydrocannabinol-9-carboxylid acid). It
is the same as the SAMHSA recommended assay cutoff.
The THC test provides only
a preliminary analytical result. A more specific alternative chemical method
must be used in order to obtain a confirmed analytical result. Gas chromatography,
mass spectrometry (GC/MS) is the preferred method. Clinical consideration
and professional judgment should be applied to any drug of abuse test result,
particularly when preliminary positive results are used.
EXPLANATION OF THE TEST
is the primary active ingredient in cannabinoids (marijuana). When ingested
or smoked, it produces euphoric effects. Users have impairment of short-term
memory and THC use slows learning. Also, it may cause transient episodes
of confusion, anxiety, or even toxic delirium. Long term, relatively heavy
use may be associated with behavioral disorders. The peak effect of smoking
THC occurs in 20-30 minutes and the duration is 90-120 minutes after one
cigarette. Elevated levels of urinary metabolites are found within hours
of exposure and remain detectable for 3-10 days after smoking. The main
metabolite excreted in the urine is 11-nor- 9-tetrahydrocannabinol-9-carboxylic
The THC test is based on the
principle of the highly specific immunochemical reactions between antigens
and antibodies, which are used for the analysis of specific substances
in urine. Major antibodies and buffers used in the THC Test Kit listed
as following; Goat anti-rabbit IgG (Control Line), mouse monoclonal antibody
against THC (Gold Conjugate), BSA-THC (Test Line) and phosphate buffer
and Tris buffer. The cutoff of the test is 50 ng/ml of THC (11-nor-9-tetrahydrocannabinol-9-carboxylic
The THC test cassette has a
letter T and C as “Test Line” and “Control Line” on the surface of the
case. Both the “Test Line” and the “Control Line” in the result window
are not visible before applying any samples. The “Control Line” is used
for procedural control. The control line should always appear if the test
procedure is performed properly and the test reagents of are working correctly.
The THC test kit contains
the following items to perform the assay:
1. THC test cassette.
2. Disposable sample dropper.
3. Instructions for use.
MATERIALS REQUIRED BUT NOT
1. Specimen collection container.
2. Clock or timer.
1. For professional in vitro
diagnostic use only.
2. Avoid cross contamination
of urine samples by using a new urine specimen container and dropper for
each urine sample.
3. Urine specimens are potentially
infectious. Proper handling and disposal methods should be established
according to good laboratory practices.
4. Do not eat or smoke while
handling specimen in the laboratory.
5. The THC device should remain
in its original sealed pouch until ready for use.
6. Do not use the test if
the pouch is damaged or the seal is broken.
7. Do not use the test kit
after the expiration date.
STORAGE AND STABILITY
The THC test kit should be
stored at 4-30 oC in the original sealed pouch. The expiration date given
was determined under normal laboratory conditions.
SPECIMEN COLLECTION AND
1. Fresh urine specimens do
not require any special handling or pretreatment.
2. Specimens should be collected
in a clean glass or plastic container.
3. If testing will not be
performed immediately, specimens should be refrigerated.
4. Specimens should be brought
to room temperature before testing.
5. Specimens containing precipitate
may yield inconsistent test results. Such specimens must be clarified prior
PROCEDURE OF THE TEST
1. Remove the test disk from
the foil packet, and place it on a flat, dry surface.
2. Holding the sample dropper
above the test disk. Squeeze 2 drops of specimen into the sample well (See
3. Interpret the test results
at 3 to 5 minutes.
INTERPRETATION OF RESULTS
1. As the test kit begins
to work, a purple band will appear at the left section of the result window
to show that the Control Line is working properly.
2. The right section of the
result window indicates the test results. If another purple band appears
at the right section of the result window, this band is the Test Band.
NEGATIVE: TWO COLOR BANDS
The appearance of two purple
bands within the result window indicates a negative test result. No THC
above the cut-off level has been detected. Note: Due to the chemical nature
of the THC, the color of the Test band is much fainter comparing to the
color of the Test band of other drugs of abuse tests. Therefore, it is
best to read a test under sufficient amount of lighting.
POSITIVE: ONE COLOR BAND
The appearance of only one
purple band within the result window indicates the result is positive,
i.e. the specimen contains THC at a concentration above the cutoff level.
The urine specimen should be
confirmed with a more specific alternative method such as gas chromatography/mass
spectrometry, before a positive determination is made.
A distinct purple band should
always appear in the left section of the result window. The test is invalid
if no purple band forms in the left section of the result window (Control
Note. A very faint band in
the right section of the result window, visible in 5 minutes, indicates
that the amount of THC in the sample is near or below the cut-off level
of the test. The urine specimen should be retested, or confirmed with a
more specific alternative method such as gas chromatography/mass spectrometry,
before a positive determination is made.
USER QUALITY CONTROL
Control standards are not
supplied with this kit; however, it is recommended that a control be tested
as good laboratory testing practice. For information on how to obtain controls,
contact Technical Service. Before using a new kit with patient specimens,
positive (cutoff and 25% more than cutoff level) and negative (25% below
cutoff level) controls should be tested to confirm the test procedure,
and to verify the tests produce the expected Q.C. results.
1. The test is designed for
use with unadulterated human urine only.
2. There is a possibility
that factors such as technical or procedural errors, as well as other substances
in the urine samples may interfere with the test and cause erroneous results.
3. Adulterants, such as bleach
and/or alum, in urine specimens may produce erroneous results regardless
of the method of analysis. If adulteration is suspected, the test should
be repeated with a new sample.
4. A positive test result
does not provide any indication of the level of intoxication or urinary
5. The test results read after
5 minutes may not be consistent with the original reading obtained within
the 5-minute reading period. The test must be read within 5 minutes of
6. Prolonged passive smoking
of THC may also produce a positive result.
The THC test is a qualitative
assay. The amount of drugs and metabolites present in the urine cannot
be estimated by the assay. The assay results distinguish positive from
negative samples. A positive result indicates the sample contains THC above
the cutoff concentration.
AND COMPARISON STUDIES
The THC test has been shown
to detect an average of 50 ng/ml or more of THC metabolites in urine. The
accuracy of the THC was evaluated in comparison to a commercially available
immunoassay. A total of 50 negative real patient urine samples (THC concentration
range of 0-34 ng/ml) and 50 positive real patient urine samples (THC concentration
range of 50-730 ng/ml) were tested by both procedures. Complete agreement
was observed in 100% of the samples. All positive and part of the negative
samples were confirmed by GC/MS.
PRECISION AND REPRODUCIBILITY
The precision of the THC assay
was determined by carrying out the test with serially spiked THC urine
samples. The four concentrations, of 0 ng/ml, -25% from the cutoff (37.5
ng/ml), cutoff (50 ng/ml) and +25 % from the cutoff (62.5 ng/ml) were tested
to challenge the precision of the test device. A total of 50 tests were
run at 0 concentration, 50 at 37.5 ng/ml, 200 at 50 ng/ml and 50 at 62.5
ng/ml. In all 350 tests were tested. About 99% of the samples containing
drug concentrations at or more than 25% over the cut-off level consistently
showed positive results.
The reproducibility studies
were carried out at three different sites. The urine samples containing
0, 50 ng/ml and 150 ng/ml of THC were tested with a total of 360 THC test
kits. The samples were tested two times in the same day, and in two different
assays, each day for 20 days. This permits separate comparisons of between-day,
between-assay and within-day results, which show good consistency.
There are a total of 200 urine
samples including 50 samples contain zero, 50 samples –25% below the cutoff
(37.5 ng/ml), 50 samples at the cutoff (50 ng/ml) and 50 samples at 25%
above the cutoff (62.5 ng/ml). Both the and the commercially available
immunoassay test kit tested all 200 urine samples. Complete agreement was
observed at 99.5% and the test cutoff established at 50 ng/ml of THC.
SPECIFICITY AND INTERRENCE
The following table lists
compounds that are detected by the THC test.
The results are expressed
in terms of the concentration required to produce a positive result.
Compound Conc. (ng/ml)
Potentially interfering chemicals
such as pain medication (Acetaminophen, 20 mg/dl), protein (2000 mg/dl),
glucose (2000 mg/dl), hemoglobin (500 mg/dl) and pH of 6.0, 7.0 and 8.0
were supplemented to normal urine specimens devoid of THC. The test gave
consistently negative results. The base line urine with 50 ng/ml THC scored
1. R.C. Baselt, Disposition
of Toxic Drugs and Chemicals in Man, 2 and ED, Biomedical Publ, Davis,
CA., p. 488, 1982.2. Urine Testing for Drugs of Abuse, National Institute
for Drug Abuse (NIDA), Research Monograph 73, 1986.