An overview of the popular methods used in drug testing
Drug analysis methods
Since hair grows at a relatively constant rate of one centimeter per month, analysis of hair strands could pinpoint the time of drug exposure to within as little as one particular week. See full text of disclaimer. Typically always requires months to years depending on difficulty of the subject Most discriminatory Mass spectrometry How does it work? The accuracy depends largely on the standards for sample collection, whether the collection was performed inside the detection window of the drug, and whether it was a random drug test or the subject had prior knowledge of the testing. Urine tests can yield false negatives if the individual has consumed large amounts of fluids prior to giving the sample. Duquenois-Levine reagent is a series of chemical solutions that turn to the color of purple when the vegetation of marijuana is added. The following are estimates of the length of time that certain drugs are detectable: Alcohol — 1 oz. To get accurate readings on a breath-testing device the individual must blow for approximately 6 seconds and need to contain roughly 1. There are also some disadvantages to spray or sweat testing. Diagnostic screening[ edit ] In the case of life-threatening symptoms, unconsciousness, or bizarre behavior in an emergency situation, screening for common drugs and toxins may help find the cause, called a toxicology test or tox screen to denote the broader area of possible substances beyond just self-administered drugs. Other measures include hiding containers of clean urine, trying to substitute other liquids for urine, or adding substances thought to mask the presence of drugs in urine. UV-vis has been used to identify MDMA, ketamine hydrochloride, cocaine hydrochloride, diazepam, phenobarbital, and barbital concentrations in the microgram range, as well as specifically identify six different compounds and for the first time, accurately discriminate some mixtures [ 41 ]. Hope Without Commitment Find the best treatment options. Sweat drug screen[ edit ] Sweat patches are attached to the skin to collect sweat over a long period of time up to 14 days.
Samples must be diluted or the technique can yield saturated spectra. Cheating on Drug Testing The most common ways in which subjects of drug screening fool the system are switching "clean" urine for "dirty" urine, submitting urine that is not their own, or saving their own clean urine for later use.
Hair testing is the least invasive form of drug testing, therefore privacy issues are decreased. It also can lead to additional costs in the form of health care claims, especially short-term disability claims.
One benefit of X-ray D is that it requires no sample preparation and does not destroy the substance being tested. There are various ionization methods.
Information about optimal technique can be easily accessed via the internet. Sensitivity is in the micro-nanogram range. Each specific named test will have information on what analytes it can be used with. False Positives. The spectroscopic expertise required to forensically analyze and quantify a substance may be difficult or impossible to find in harm reduction clinics.
When were drug tests invented
It has also been argued that such testing potentially implicates the Fifth Amendment privilege against self-incrimination , the right to due process including the prohibition against gathering evidence in a manner that shocks the conscience or constitutes outrageous government conduct , and the prohibition against unreasonable searches and seizures contained in the Fourth Amendment. Hair testing cannot be used to detect for alcohol use. However, quantitative analysis can pose a problem with unknown samples and mixtures. However, when used in conjunction, TLC and UV can be quite powerful in identification of a wide variety of substances including mixtures and offer a more rudimentary quantification than the more discriminatory techniques. The fact that this technology is so cost-effective, easy to perform, and requires a very minute amount of substance makes it really stand out from many of the other presumptive methods [ 16 ]. The second is the threshold or cut-off value, or a value above the limit of detection that is selected based on prior tests. The person being tested blows into a breath-alcohol device, and the results are given as a number, known as the Blood Alcohol Concentration BAC , which shows the level of alcohol in the blood at the time the test was taken. For this reason, urine tests are generally not helpful in detecting alcohol use as opposed to illicit and prescription drug use, which is more easily traced in urine.
Urine is typically analyzed by a rapid method that relies on immunochemistry or a means of testing that detects the presence of the drug or the drug metabolite. A small amount of the scattered light is shifted in energy from the laser frequency due to electromagnetic and molecular interactions in the sample [ 26 ].
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