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Most people who take a drug test take a presumptive test, cheaper and faster than other methods of testing. However, it is less accurate and can render false results. The FDA recommends for confirmatory testing to be conducted and the placing of a warning label on the presumptive drug test: "This assay provides only a preliminary result.
The Kastle–Meyer test is a form of catalytic blood test, one of the two main classes of forensic tests commonly employed by crime labs in the chemical identification of blood. The other class of tests used for this purpose are microcrystal tests, such as the Teichmann crystal test and the Takayama crystal test. [1] Joseph Hoeing Kastle
As with all presumptive tests, this technique can produce false positive results due to metals and strong chemicals, such as bleach, that will also react. Another common presumptive test is the Kastle-Meyer or Phenolphthalein test. This is a catalytic test that detects the heme group in blood that transports oxygen and carbon dioxide. [5]
The above photo shows the positive results of the number 2 Marquis reagent presumptive drug test when used with a sample of opium. It is the primary presumptive test used in Ecstasy reagent testing kits. It can also be used to test for such substances as opiates (e.g. codeine, heroin), and phenethylamines (e.g. 2C-B, mescaline).
In the forensic detection of blood, the catalyst is the iron present in hemoglobin. [7] Enzymes in a variety of biological systems may also catalyse the decomposition of hydrogen peroxide. The exact mechanism of luminol chemiluminescence is a complex multi-step reaction, especially in aqueous conditions.
Simon's reagent is used as a simple spot-test to presumptively identify alkaloids as well as other compounds. It reacts with secondary amines like MDMA and methamphetamine to give a blue solution. Uses
The Duquenois reagent is used in the Rapid Modified Duquenois–Levine test (also known as the simple Rapid Duquenois Test), which is an established screening test for the presence of cannabis. The test was initially developed in the 1930s by the French medical biochemist Pierre Duquénois (1904–1986) and was adopted in the 1950s by the ...
Forensic chemistry is the application of chemistry and its subfield, forensic toxicology, in a legal setting. A forensic chemist can assist in the identification of unknown materials found at a crime scene. [1] Specialists in this field have a wide array of methods and instruments to help identify unknown substances.