Hair Follicle Test
Hair follicle as a specimen? Amazing, isn't? Wonder how it happens?
As soon as you take in barbiturates, the its active chemicals will start to circulate through your body. These chemicals, or some other chemicals called metabolites which are produced when your body processes the drug, can accumulate in your hair follicles. As a strand of hair grows, its follicle will deposit these chemicals in it. Hair tests look for these chemicals in a small sample of your hair.
How is it done? A small sample of your hair (usually 1-3 clumps of about 50 strands each) is cut. Most cuts are taken from the back of the head so as not to ruin your haircut.
The standard detection window for the hair test is 90 days. Because hair grows about 1.5 inches in 90 days, hairs with a length of about 1.5 inches are targeted for cutting. Longer hairs will give a longer window of detection. For instance, a 6-inch long strand of hair can potentially reveal drug use from a year ago. However, 90 days is the most common testing window, so, generally, long strands of hair are cut to 1.5 inches before being tested.
Bald? Have a shaved head? Your problem is solved! Hair from other parts of your body can be used for testing. For drug users, this is usually worse - body hair grows more slowly than head hair, so it can reveal drug use from up to a year in the past.
H o w e v e r , because of the fact that it can take up to a week for drug-affected hair to grow above the scalp, hair tests can miss very recent drug use. Because of this, some employers may require a urine drug test as well. It can detect most drug use within the last few days.
As soon as you take in barbiturates, the its active chemicals will start to circulate through your body. These chemicals, or some other chemicals called metabolites which are produced when your body processes the drug, can accumulate in your hair follicles. As a strand of hair grows, its follicle will deposit these chemicals in it. Hair tests look for these chemicals in a small sample of your hair.
How is it done? A small sample of your hair (usually 1-3 clumps of about 50 strands each) is cut. Most cuts are taken from the back of the head so as not to ruin your haircut.
The standard detection window for the hair test is 90 days. Because hair grows about 1.5 inches in 90 days, hairs with a length of about 1.5 inches are targeted for cutting. Longer hairs will give a longer window of detection. For instance, a 6-inch long strand of hair can potentially reveal drug use from a year ago. However, 90 days is the most common testing window, so, generally, long strands of hair are cut to 1.5 inches before being tested.
Bald? Have a shaved head? Your problem is solved! Hair from other parts of your body can be used for testing. For drug users, this is usually worse - body hair grows more slowly than head hair, so it can reveal drug use from up to a year in the past.
H o w e v e r , because of the fact that it can take up to a week for drug-affected hair to grow above the scalp, hair tests can miss very recent drug use. Because of this, some employers may require a urine drug test as well. It can detect most drug use within the last few days.
Urine Test
A urine drug screening immunoassay is a frequent practice used to detect barbiturates along with other drugs in the system. It contains specific antibodies against common drugs of abuse and their metabolites.
Immunoassays are the most commonly employed methods for urine drug screens because they are rapid and econocmical. Five different immunoassays are available: cloned enzyme donor immunoassay, enzyme-multiplied immunoasssay (EMIT), fluorescence polarization immunoassay (FPIA), and immunoturbidimetricassay radioimmunoassay (RIA).
One major problem with immunoassays is a false-positive results. Some known drugs that interefere with testing and cause flase results in barbiturate tests are Ibuprofen and Naproxen. Although immunoassays are very sensitive to the presence of drugs and drug metabolites, specificity and accuracy varies depending on the assay used and the substance for detection. This limitation may result in false-positives from substances cross-reacting with the immunoassay.
False-negatives, on the other hand, may result from:
It is necessary that a proper urine collection is observed to avoid false-negative results. Urine should be collected in a tamper-evident container under supervision if necessary. Criteria for legitimate urine samples include:
Urine samples with characteristics outside of these ranges, or with a cloudy or dark appearance, may be adulterated in some manner, either diluted or substituted.
Immunoassays are the most commonly employed methods for urine drug screens because they are rapid and econocmical. Five different immunoassays are available: cloned enzyme donor immunoassay, enzyme-multiplied immunoasssay (EMIT), fluorescence polarization immunoassay (FPIA), and immunoturbidimetricassay radioimmunoassay (RIA).
One major problem with immunoassays is a false-positive results. Some known drugs that interefere with testing and cause flase results in barbiturate tests are Ibuprofen and Naproxen. Although immunoassays are very sensitive to the presence of drugs and drug metabolites, specificity and accuracy varies depending on the assay used and the substance for detection. This limitation may result in false-positives from substances cross-reacting with the immunoassay.
False-negatives, on the other hand, may result from:
- Dilute urine (excess fluid intake, diuretic use, pediatric sample)
- Infrequent drug use
- Prolonged time since last use
- Recent ingestion
- Insufficient quantity ingested
- Metabolic factors
- Inappropriate test used
- Elevated urine lactate
- Tampering
- Tetrahydrozoline (eye drops)
- Bleach
- Vinegar
- Soap
- Ammonia
- Lemon juice
- Drain cleaner
- Table salt
- Various chemicals (glutaraldehyde, sodium or potassium nitrate, pyridinium chlorochromate, and peroxide/peroxidase)
It is necessary that a proper urine collection is observed to avoid false-negative results. Urine should be collected in a tamper-evident container under supervision if necessary. Criteria for legitimate urine samples include:
- A volume of 30 mL or more
- Temperature between 32▫C and 38▫C
- pH of 4.5 to 8.5
- Nitrates <500 mcg/mL
- Specific gravity >1.002 and <1.020
- Creatinine >20 mg/dL
Urine samples with characteristics outside of these ranges, or with a cloudy or dark appearance, may be adulterated in some manner, either diluted or substituted.