Drug Test methods
An assay can be developed for any drug using GC/MS. The table below indicates what can be detected in typical screening tests.
|Y = Detectable
N = Not detectable
U = Unknown
DrugAlert is a .95 home test kit enabling parents to test their children. This is the most inaccurate test being used, and also the newest. The test kit is a small brown pad giving off an odor. The parent wipes the child's clothes, books and anything belonging to the child. Then the pad is sent to Barringer Technologies via mail.
If the sample is positive, Barringer Technologies is knowingly urging parents to break the law by sending controlled substances via mail. The lab puts the pad in a machine, which detects residue from seven different illicit drugs. The child fails the test if s/he uses drugs, or unknowingly comes in casual contact with a drug user. Simply borrowing a pencil from a classmate that uses drugs will pass enough residue to render a positive test. When statistics such as “90% of all paper currency shows traces of cocaine” are prevalent, this test kit is quite foolish. Your only defense is to continually clean everything you touch with disinfectants.
Gas chromatography uses a separation technique to divide the urine extracts into the component parts. An inert gas carries the urine through chromatographic columns, and the samples are separated by their boiling temperature and affinity for the column. Compounds are identified by separation time, called retention time. The retention time is unique and reproducible for each drug in a given chromatographic column.
The most precise procedure for the detection of banned substances is a combination of gas chromatography (GC) and mass spectrometry (MS). GS/MS is a two-step process where GC separates the sample into its constituent parts, while MS provides the exact molecular identification of the compounds. Compounds are separated by GC and are then introduced, one at a time, into a mass spectrometer. As the sample constituents enter the MS, they are bombarded by electrons, which cause the compound to break up into molecular fragments. The fragmentation pattern is reproducible and characteristic, and is considered the "molecular fingerprint" of a specific compound. GC/MS is considered to be the most definitive method for confirming the presence of a drug in the urine and is approximately 100 to 1,000 times more sensitive than TLC. Selective ion monitoring has been used to improve the GC/MS results. This procedure is also the most costly by far of all testing methods.
GC/MS is typically used to confirm "positive" EMIT test results. GC/MS will indicate precisely what chemical is present. This is necessary because the EMIT will only indicate whether something similar to what's being tested for was found. The GC/MS is difficult and more costly, which is why the EMIT is given first. Abstinence and substitution are the only ways to defeat the GC/MS test. GC/MS is very precise when done right. However, it's still subject to human error. For example, if the equipment isn't cleaned well, the previous test sample could get mixed with the next sample. According to Dr. Edward Cone, the GC/MS is 99 percent accurate; not very accurate on a large scale when you realize that 10 thousand out of every million will get false results.
When metabolites are in the blood, they go through the blood vessels in the head and get filtered through the hair. Metabolites remain in the hair as a permanent record. The hair test costs several hundred dollars and is rarely given because urinalysis is cheaper and more accurate. According to Jeff Nightbyrd, hair tests are "widely used in the casino industry." They cut 50 strands of hair from the scalp, and send it in to the testing lab where they liquefy it. "A hair sample is dissolved in a series of solvents which extract the drug metabolites and then are analyzed via GC/MS," says Nightbyrd.
It can take several days to extract metabolites. Average hair growth is 1/4 inch per month. Typically labs use hair 1.5” from the scalp, though some labs will take enough to test for up to 3 years. The liquid is run through the most
sensitive GC/MS machines available, and can detect as little as 1 ng/mL. The hair test discriminates in that detection is easier in dark hair. Non-Caucasians may be discriminated against further because melanin is in their hair, which
can be mistaken for THC. However, there is conflicting data as to whether melanin can be detected as THC.
Beating the hair test is extremely hard, and there are false positives. Bleaching or dying your hair is rumored to work, but it most assuredly does not.
If you have an impending hair follicle test, NeonJoint can only recommend the hair follicle drug test treatment program offered by PassYourTest.com. After several years, PassYourTest.com remains the only supplier of detoxification products we at NeonJoint will even mention by name.
Fortunately, the hair test cannot be used alone as evidence because there are no forensic standards. It can only be used when substantiated by other evidence.
This test is usually used to detect anabolic steroids. Defined by Thein and Landry:
“High-performance liquid chromatography is similar to GC, except a liquid carries the sample through the chromatographic columns and the columns are not placed in a heated compartment. High-performance liquid chromatography is both sensitive and specific, and it is simpler and faster than GC. Gas chromatography and HPLC are reliable methods for screening, and they allow for simultaneous determination of a wide variety of different compounds.”
High-performance liquid chromatography is used to screen for urinary caffeine levels and has been used to confirm the positive results obtained from other screening techniques. Some steroids can be analyzed with this technique, whereas HPLC and GC lack appropriate sensitivity to detect beta-adrenergic blockers.
This procedure is best described in Thein and Landry's words:
“Immunoassays use antigen-antibody interactions to detect illegal substances. Antibodies that bind selectively to certain drugs or drug metabolites are chosen, and the sensitivity and the specificity of this test are only as good as the antibody chosen. The binding is proportional to the amount of drug in the urine and can be detected through enzymes, radioisotopes or fluorescent compounds.
With this technique, very small amounts of a drug can be detected in a very small amount of urine, although this test may not differentiate between specific drugs within a class of drugs. Immunoassay has yielded false-positive results with some decongestants and non-steroidal anti-inflammatory drugs. Radioimmunoassay (RIA) and fluorescence polarization immunoassay (FPIA) are specific IA techniques currently being used. Radioimmunoassay can detect some 17 alpha-methyl, 17 alpha-ethyl, and 19-nortestosterone steroids despite its low specificity. Immunoassay is both more sensitive and more specific than TLC.”
The RIA test is applied the same way as the EMIT. "The only difference between RIA and EMIT is that RIA uses radioactive iodine as the detection mechanism rather than an enzyme NAD/NADH which is detected by a scintillation counter." The scintillation counter is used to measure the amount of radioactive particles present. Radioactivity is inversely proportional to metabolite level. RIA tests are a little more sensitive than the EMIT, and harder to beat. The most known user of the RIA test is the US government; in particular, the US military. The EMIT is more common because RIA produces radioactive waste, and radioactive waste is difficult to deal with. The US government uses RIA because a "company gives the government the instrumentation free in exchange for buying their reagents (reagent rental contract)." Some non-government labs use the RIA, so do not be surprised if your pre-employment screening is a RIA rather than an EMIT.
The EMIT is the cheapest, easiest to perform and most common; it is also the easiest to fail. It's the easiest to pass if you're well informed (i.e. reading this text). Most pre-employment screens will give you the EMIT first, though some businesses will surprise you with a GC/MS test upfront. If you don't know which urinalysis will be administered, focus on beating the EMIT. If you pass the EMIT, you're off the hook. If you fail the EMIT, they'll give you the confirmation GC/MS test, which is extremely sensitive. Lewis Maltby, director of the Workplace Rights Office, said the EMIT test is wrong 25 to 30 percent of the time.
Fluorescence polarization immunoassay (FPIA) takes advantage of the increased polarization of fluorescent light emissions when a fluorescently labeled antigen is bound by reagent antibody. The higher the concentration of unlabeled patient antigen present in the test mixture, the less bound fluorescent antigen is present. Standard calibration yields quantitative results.
A band-aid type patch is worn for a week or more to absorb perspiration. If illicit drugs are used during the time the sweat patch is worn, the patch will be positive when the lab tests it. The patch has a tamper-proof design. PharmChem Laboratories Inc. created the patch, and received market approval from the FDA. The FDA permitted the patch for detecting cocaine, amphetamines and opiates. They are working on getting FDA clearance to use the patch to test for marijuana and PCP. The FDA already gave permission to use it in the workplace. PharmChem sold the patch to law enforcement and drug rehabilitation agencies in 1996. Accuracy of the sweat patch remains unknown. No one has disclosed any information regarding how inaccurate this test is. Bad lab procedure is a very big problem in the testing industry, and it's hard to tell how prone to human error the sweat patch test is.
TLC "involves adding solvent to urine to extract drugs and then comparing color spots on a TLC plate to that of a standard" (Nightbyrd). Accuracy is very poor, and this test is rarely used. Thein and Landry's definition:
“Thin-layer chromatography testing is based on the differences in the migration rate of various substances through a porous supporting medium. The degree of migration and the color are characteristic of certain drugs. Thin-layer chromatography can demonstrate the presence of a drug, but this procedure cannot specify the quantity of drug present. This technique is both time consuming and nonspecific, and provides only a positive or negative response. Thin-layer chromatography is capable of detecting only a limited number of substances 12 to 24 hours after ingestion, resulting in a high number of false-negative results.”