Drug Testing - How Does Drug Testing Work

Most drug testing is broken down into two categories, urine testing or urinalysis and hair testing. The labs are not looking for drugs in urine samples; they are looking for drug metabolites. Once the body takes in a substance, the end product looks much different, once it passes through. Alcohol goes in as beer, gets oxidized by the liver, and comes out as water. Drugs go in the body in the psychedelic form and come out as a metabolite. The psychoactive ingredient in marijuana is 11-nor-D-9-tetrahyrocanibinol (THC). This is oxidized by the body and comes out as 31 different metabolites. The most prevalent form is 11-nor-D-9-tetrahyrocanibinolic acid (THCA).

Marijuana is passed from the lungs to the blood stream, and while the drug is freely floating in the body in sufficient quantity a high is felt. Marijuana is liposoluble, meaning it absorbs into fat cells. The drug is stored in the fat cells indefinitely untill the body burns the fat cells for energy. When the cell is burned, the drug is metabolized and released back into the blood stream. This is why marijuana can be detected for 30 days after a substantial usage.

Urinalysis is typically separated into two separate sections, the drug screen and the drug test or confirmation. There is a huge difference between a drug screen (EMIT) and a drug test. Most drug testing procedures utilize a drug screen and test (GC/MS). However, some employers or institutions in an attempt to cut costs will only use drug screens. The screen is always performed first and is usually followed by a test or confirmation. Drug Testing is broken down in the following percentages:

Hair Testing -- 5% Screen with GC/MS -- 80%
Screen Only -- 5% FPIA (Screen) -- 5%
  • GC/MS = Gas Chromatography/Mass Spectrometry
  • Screen = EMIT - Enzyme Multiplied Immunoassay Test (Trade name for the most popular screen used in drug testing field manufactured by Dade Behring )
  • FPIA = Florescence Polarization Immunoassay - Abbott Labs version of a screen

D.O.T - a DOT test is the abbreviation for a Department of Transportation. This means the testing guidelines have been regulated by the DOT, and if the guidelines are not followed the results are considered invalid. Not all tests are DOT regulated, but most are. To make the testing process easier companies follow the DOT guidelines to minimize mistakes.

The first test for the DOT is a five panel EMIT. The cut off for marijuana on the screen is 50 ng/ml, which is a composite of all 31 metabolite concentrations. If the sample is below this level the test is over as a passing status. If the sample is over 50 ng/ml the sample is sent on to a GC/MS for confirmation. The cutoff for the confirmation is lower at 15 ng/ml because the machine only identifies one of the 31 metabolites which is the 11-nor-D-9-tetrahyrocanibinolic acid. To pass, the one metabolite must be below the 15-ng/ml cutoff. Urine LuckTM works best on DOT tests which utilize a GC/. The chart below summarizes five drugs of abuse found on the screen.

Drug # of Metabolites EMIT cut off GC/MS cut off
Marijuana 31 50 ng/ml 15 ng/ml
Cocaine 4 300 ng/ml 150 ng/ml
Opiates 3 2000 ng/ml 2000 ng/ml
Phencyclidine 1 25 ng/ml 25ng/ml
Amphetamines 5 1000 ng/ml 500 ng/ml

DOT tests are the hardest test to pass if the donor does not use a detoxifying product. However, if a detoxifying product is used, the DOT is the easiest test pass. Each type of detoxifying product works via a unique mechanism on drug tests. Refer to the product sections of this report for the mechanism information and explanation. Guidelines for the DOT test procedures, reporting, and adulteration, can be found on the Department of Health and Human Services or the Department of Transportation web page at www.dot.gov/ost/dapc/guidelines/Urine.htm .


Blood Test - Often people will be given a blood test and a urinalysis. These are for two totally different types of tests being performed. Blood is normally drawn for detection of diseases such as AIDS. Drug toxins can only be detected for 48 hours in the blood after consumption. For this reason the urine is tested for toxins instead of the blood.

Hair Tests - Toxins are circulated throughout the body via the blood stream. The blood feeds the hair while it is in the growth stage at the scalp. As the hair is formed the toxins are trapped inside the hair folic. The toxins then grow away from the scalp as time passes. If the use of toxins is stopped, the hair by the scalp is clean, but the middle of the hair or ends of hair will retain the toxins until cut off. The level of toxins is greatest near the scalp. Sunlight and chemicals added to the hair in dyes or shampoos will oxidize the drug metabolites over years, and can reduce the level of metabolites by 75%.

For this reason, the hair sample is clipped from the back neck (nape) near the scalp by the examiner. Once sent to a laboratory the hair is dissolved with organic solvents. Once in a liquid solution, the toxins are freed from within the hair follicle. Extraction is performed on the liquid and drug toxins are removed. Once the drug metabolites are isolated a GC/MS is performed with urinalysis testing and quantitative level is provided.