
Reagent testing

Reagent testing is one of the processes used to identify substances contained within a pill, usually illicit substances.
With the increased prevalence of drugs being available in their pure forms, the terms "drug checking" or "pill testing" may also be used, although these terms usually refer to testing with a wider variety of techniques covered by drug checking.
Reagent testing kits.
A test is done by taking a small scraping from a pill and placing it in the reagent testing liquid or dropping the reagent onto the scraping. The liquid will change colour when reacting with different chemicals to indicate the presence of certain substances.
Testing with a reagent kit does not indicate the pill is safe. While the testing process does show some particular substances are present, it may not show a harmful substance that is also present and unaccounted for by the testing process. Some substances that cause strong colour changes can also mask the presence of other substances that cause weaker colour changes. Thin layer chromatography is used with reagent testing to separate substances before testing and prevent this "masking" effect.
Testing kits are distributed on a not-for-profit basis by Dancesafe and commercially.
 It is advised to check the references for photos of reaction results.
Reagent testers might show the colour of the desired substance while not showing a different colour for a more dangerous additive. For this reason it is essential to use multiple different tests to show all adulterants.
Tests available.
As reagent testing has become more popular, vendors have begun to offer a greater range of tests. This increases the likelihood that a substance might have a unique profile of results and makes the tests more useful.
Other reagents are discussed in scientific literature but limited applications mean they may not be sold for consumer testing. The zimmermann reagent for benzodiazepines is a good example - its use is limited to benzodiazepines, and when these are mis-sold it is usually by substitution of a different benzodiazepine, rendering the test unuseful for consumers.
The Ehrlich reagent is an example of a single-application reagent which is used by consumers. It can only detect drugs with an indole moiety, but this is useful because drugs from the NBOMe class do not have an indole and are often sold as LSD which does. The Ehrlich reagent has an additional benefit over other reagents in that it does not react with the paper on which LSD is often distributed.
The National Institute of Justice provides information about "Color Test Reagents/Kits for Preliminary Identification
of Drugs of Abuse" in NIJ Standard–0604.01.
Tests reliability.
According to a 2003 research published in "Pharmacotherapy", neither the Marquis, Mecke, nor Simon's reagents should be used by the public for harm reduction purposes. These agents do not help identify pure MDMA tablets. The research team suggests using gas chromatography-mass spectrometry as the most sensitive and specific testing method for identifying MDMA and its contaminants but this is out of reach for users in most countries and reagent tests remain popular, often distributed by harm-reduction organisations due to their low cost and high utility when multiple test reagents are used.
Legality.
Home pill testing equipment is illegal in the US state of Illinois where the (720 ILCS 600/) Drug Paraphernalia Control Act specifically outlaws "testing equipment intended to be used unlawfully in a private home for identifying or in analyzing the strength, effectiveness or purity of cannabis or controlled substances;"