The Marquis reagent is used as a simple spot-test to presumptively identify alkaloids as well as other compounds. It is composed of a mixture of formaldehyde and concentrated sulfuric acid, which is dripped onto the substance being tested. Different compounds produce different colour reactions. Also some times methanol is added to slow down the reaction process to observe the change in colour better. Methanol does this by slowing down the polymerisation process. An alkaloid is a nitrogenous organic molecule that has a pharmacological effect on humans and other animals. ... The chemical compound formaldehyde (also known as methanal) is a gas with a pungent smell. ... Sulfuric (or sulphuric) acid, H2SO4, is a strong mineral acid. ...
It is the primary presumptive test used in Ecstasy testing kits. It can also be used to test for such substances as cocaine, opiates (e.g. methadone, heroin), and phenethylamines (e.g. methamphetamine, amphetamine). MDMA (3,4-methylenedioxymethamphetamine), most commonly known by the street names ecstasy or XTC (for more names see the full list), is a synthetic entactogen of the phenethylamine family, whose primary effect is believed to be the stimulation of secretion as well as inhibition of re-uptake of large amounts...
The test is performed by scraping off a small amount of the substance and adding a drop of the reagent (which is initially clear). The results are analyzed by viewing the color of the resulting mixture, and by the time taken for the change in color to become apparent:
A reagent is any substance used in a chemical reaction chemical reaction is a process involving one, two or more substances (called reactants), characterized by a chemical change and yielding one or more product(s) which are different from the reactants.
The word "reagent" has also been used in some fantasy fantasy is a form of speculative fiction in which physical laws differ from our own through a reason for which no scientific explanation is offered, or which take place a world wholly different from our own.
Silver nitrate is a reagent used for detection for halides (chloride, iodide, bromide, flouride) ions, particularly for chlorides.
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