Urine is the specimen of choice since it contains the most metabolites of a drug taken. Urine samples are taken from an individual and delivered to the testing lab in a specimen cup.
EMIT (Enzyme Multiplied Immunoassay Technique) – the most commonly used test for pre-employment drug screenings despite having a 4-34% “false positive” rate. RIA (Radioimmunoassay) – primarily used in the military, this test is highly sensitive. TRIAGE – this widely used test has shown to produce over 50% “false positives” results on drug-free urine.
TLC (Thin Layer Chromatography) – not widely used since results are not very reliable. GC/MS (Gas Chromatography/Mass Spectrometer) – the most sophisticated test (over 99.8% accurate) and the most expensive type of testing, used to confirm initial EMIT test results if they are positive.
Hair testing is a relatively new technique for detecting drug use. With a one-inch hair sample containing about 50 strands, It’s usually used to detect drug use within the past 90 days. If you have very short hair, labs can take a sample from any part of the body. Hair testing is widely used in the casino industry. People with dark hair are 10-50 times more likely to test positive.
The use of the sweat patch to detect drug use was recently approved by the FDA. The patch is used mainly to monitor people on parole or probation. The patch is tamper proof and each one has a serial number.
Recently there has been extensive research on the use of saliva in drug testing. It simply involves using a swab that looks very similar to a common toothbrush but in place of bristles a pad that servers, to collect the saliva the pad is placed between the lower cheek and gum for about two minutes. Once saturated with saliva the pad is then transferred to a collection vial. Many of the most commonly abused drugs can be detected in saliva including marijuana, THC, heroin, cocaine, and amphetamines. Saliva testing is mainly used for on-site intoxication and is becoming more common in the workplace.
Although expensive and intrusive, blood testing is the most accurate confirmation of drug use. Since blood testing measures the accurate presence of the drug or its metabolite at the time of testing, the results from this type of test are the best indication of intoxication. Blood testing for the use of drugs is primarily used in accident investigations and for health insurance or life insurance exams. Marijuana drug use can be detected rapidly up to six hours after consumption by testing blood; after that, the metabolite concentration falls rapidly, and marijuana may be detectable for up to 22 hours but is usually not detectable in blood past 22 hours.