Drug Test Facts

EMIT Urinalysis Drug Test

The most commonly used method of screening for drug use is the five panel, Enzyme Multiple Immunoassay Test (EMIT). Five drugs are tested for with the qualitative detection of cocaine, amphetamines, methamphetamines (ecstasy), opiates (heroin, morphin),pcp (angels dust,hog) and tetrahydrocannabinol (marijuana, hashish) drug testing in urine. The cutoff levels of the test for cocaine (COC) is 300 ng/ml, methamphetamine (METH) is 1000 ng/ml, opium (OPI) is 300 ng/ml, phencyclidine (PCP) is 25 ng/ml and marijuana (THC) is 50 ng/ml.

Drug Test Results

Positive: A rose-pink band is visible in each control zone. No color band appearing in the appropriate test zone indicates a positive result for the corresponding drug of that specific test zone.

Negative: A rose-pink band is visible in each control zone and the appropriate test zone, indicating that the concentration of the corresponding drug of that specific test zone is below the detection limit of the test.

Invalid: If a color band is not visible in each of the control zones, the test is invalid. Another test should be run to re-evaluate the specimen.

The process involves two drug metabolites, one provided in the urine of the donor, the other supplied by the lab. These metabolites compete to bind with one antibody. Three reagents are introduced into the urine to facilitate testing and provide one of two results, positive or negative. The result is based on which metabolite the antibody binds with.

GC MS: Gas Chromatography Mass Spectrometer

This test is normally only used after the initial EMIT screen indicates a positive result. The positive sample is sent to the lab and the GC/MS is performed.

The GC is used to separate the molecules that are then analyzed by the Mass Spectrometer. A solution is added to the urine that converts drug metabolites into a form that is reactive to Gas Chromatography. The sample is heated to convert it to gas and the gas is collected in columns that isolate drug metabolites found in the sample. The gas samples are collected at distinct intervals, (the conversion rate from solid to gas being known) and moved to the Mass Spectrometer.

The collected sample is bombarded with electrons creating a cation, ionization then accelerated by an electrical field and forced through a receptor that only allows certain particles to pass. This in turn is forced through a magnetic field that has a controlled strength. The sample and the field are oppositely charged creating deflection of particles that are then forced through another receptor and into a collector. Because the operator controls the electrical and magnetic fields the mass of the cation is readily determined. Every compound has a specific weight and charge and can be identified by these properties. It is a relatively simple matter then to determine the presence of drug metabolites and confirm drug usage by the donor.