Urine<unk>  screen Urine analysis is primarily used because of its low cost. Urine<unk> ing is one of the most common testing methods used. The enzyme-multiplied immune test is the most frequently used urinalysis. Complaints have been made about the relatively high rates of false positives using this test. Urine<unk> s screen the urine for the presence of a parent<unk>  or its metabolites. The level of<unk>  or its metabolites is not predictive of when the<unk>  was taken or how much the patient used. Urine<unk> ing is an immunoassay based on the principle of competitive binding.<unk> s which may be present in the urine specimen compete against their respective<unk>  conjugate for binding sites on their specific antibody. During testing, a urine specimen migrates upward by capillary action. A<unk> , if present in the urine specimen below its cut-off concentration, will not saturate the binding sites of its specific antibody. The antibody will then react with the<unk> -protein conjugate and a visible colored line will show up in the test line region of the specific<unk>  strip. A common misconception is that a<unk>  that is testing for a class of<unk> s, for example, opioids, will detect all<unk> s of that class. However, most opioid tests will not reliably detect oxycodone, oxymorphone, meperidine, or fentanyl. Likewise, most benzodiazepine<unk> s will not reliably detect lorazepam. However, urine<unk>  screens that test for a specific<unk> , rather than an entire class, are often available. When an employer requests a<unk>  from an employee, or a physician requests a<unk>  from a patient, the employee or patient is typically instructed to go to a collection site or their home. The urine sample goes through a specified 'chain of custody' to ensure that it is not tampered with or invalidated through lab or employee error. The patient or employee's urine is collected at a remote location in a specially designed secure cup, sealed with tamper-resistant tape, and sent to a testing laboratory to be screened for<unk> s (typically the Substance Abuse and Mental Health Services Administration 5 panel). The first step at the testing site is to split the urine into two aliquots. One aliquot is first screened for<unk> s using an analyzer that performs immunoassay as the initial screen. To ensure the specimen integrity and to detect possible adulterants, additional parameters are tested for. Some test the properties of normal urine, such as, urine creatinine, pH, and specific gravity. Others are intended to catch substances added to the urine to alter the test result, such as, oxidants (including bleach), nitrites, and gluteraldehyde. If the urine screen is positive then another aliquot of the sample is used to confirm the findings by gas chromatography—mass spectrometry (GC-MS) or liquid chromatography - mass spectrometry methodology. If requested by the physician or employer, certain<unk> s are screened for individually; these are generally<unk> s part of a chemical class that are, for one of many reasons, considered more habit-forming or of concern. For instance, oxycodone and diamorphine may be tested, both sedative analgesics. If such a test is not requested specifically, the more general test (in the preceding case, the test for opioids) will detect most of the<unk> s of a class, but the employer or physician will not have the benefit of the identity of the<unk> . Employment-related test results are relayed to a medical review office (MRO) where a medical physician reviews the results. If the result of the screen is negative, the MRO informs the employer that the employee has no detectable<unk>  in the urine, typically within 24 hours. However, if the test result of the immunoassay and GC-MS are non-negative and show a concentration level of parent<unk>  or metabolite above the established limit, the MRO contacts the employee to determine if there is any legitimate reason—such as a medical treatment or prescription. On-site instant<unk> ing is a more cost-efficient method of effectively detecting substance use amongst employees, as well as in rehabilitation programs to monitor patient progress. These instant tests can be used for both urine and saliva testing. Although the accuracy of such tests varies with the manufacturer, some kits have rates of accuracy correlating closely with laboratory test results. Breath test Breath test being used on a volunteer. Breath test is a widespread method for quickly determining alcohol intoxication. A breath test measures the alcohol concentration in the body by a deep-lung breath. There are different instruments used for measuring the alcohol content of an individual though their breath. Breathalyzer is a widely known instrument which was developed in 1954 and contained chemicals unlike other breath-testing instruments. More modernly used instruments are the infrared light-absorption devices and fuel cell detectors, these two testers are microprocessor controlled meaning the operator only has to press the start button. To get accurate readings on a breath-testing device the individual must blow for approximately 6 seconds and need to contain roughly 1.1 to 1.5 liters of breath. For a breath-test to result accurately and truly an operator must take steps such as avoiding measuring “mouth alcohol” which is a result from regurgitation, belching, or recent intake of an alcoholic beverage. To avoid measuring “mouth alcohol” the operator must not allow the individual that's taking the test to consume any materials for at least fifteen minutes before the breath test. When pulled over for a driving violation if an individual in the United States refuses to take a breath test that individual's driver's license can be suspended for a 6 to 12 months time period. Hair testing Hair analysis to detect addictive substances has been used by court systems in the United States, United Kingdom, Canada, and other countries worldwide. In the United States, hair testing has been accepted in court cases as forensic evidence following the Frye Rule, the Federal Rules of Evidence, and the Daubert Rule. As such, hair testing results are legally and scientifically recognized as admissible evidence. Although some lower courts may have accepted hair test evidence, there is no controlling judicial ruling in either the federal or any state system declaring any type of hair test as reliable. Hair testing is now recognized in both the UK and US judicial systems. There are guidelines for hair testing that have been published by the Society of Hair Testing (a private company in France) that specify the markers to be tested for and the cutoff concentrations that need to be tested. Addictive substances that can be detected include Cannabis, Cocaine, Amphetamines and<unk> s new to the UK such as Mephedrone. Alcohol In contrast to other<unk> s consumed, alcohol is deposited directly in the hair. For this reason the investigation procedure looks for direct products of ethanol metabolism. The main part of alcohol is oxidized in the human body. This means it is released as water and carbon dioxide. One part of the alcohol reacts with fatty acids to produce esters. The sum of the concentrations of four of these fatty acid ethyl esters (FAEEs: ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate) are used as indicators of the alcohol consumption. The amounts found in hair are measured in nanograms (one nanogram equals only one billionth of a gram), however with the benefit of modern technology, it is possible to detect such small amounts. In the detection of ethyl glucuronide, or EtG, testing can detect amounts in picograms (one picogram equals 0.001 nanograms). However, there is one major difference between most<unk> s and alcohol metabolites in the way in which they enter into the hair: on the one hand like other<unk> s FAEEs enter into the hair via the keratinocytes, the cells responsible for hair growth. These cells form the hair in the root and then grow through the skin surface taking any substances with them. On the other hand, the sebaceous glands produce FAEEs in the scalp and these migrate together with the sebum along the hair shaft (Auwärter et al., 2001, Pragst et al., 2004). So these glands lubricate not only the part of the hair that is just growing at 0.3 mm per day on the skin surface, but also the more mature hair growth, providing it with a protective layer of fat. FAEEs (nanogram = one billionth of a gram) appear in hair in almost one order of magnitude lower than (the relevant order of magnitude of) EtG (picogram = one trillionth of a gram). It has been technically possible to measure FAEEs since 1993, and the first study reporting the detection of EtG in hair was done by Sachs in 1993. In practice, most hair which is sent for analysis has been cosmetically treated in some way (bleached, permed etc.). It has been proven that FAEEs are not significantly affected by such treatments (Hartwig et al., 2003a). FAEE concentrations in hair from other body sites can be interpreted in a similar fashion as scalp hair (Hartwig et al., 2003b). Presumptive substance testing Presumptive substance tests attempt to
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