The Marquis test is a presumptive drug test used to detect the presence of certain drugs in a sample. It involves adding a few drops of a reagent called the Marquis reagent to a small sample of the substance being tested. The reagent then reacts with the substance to produce a color change that can be observed and interpreted.
The Marquis test is commonly used to detect the presence of opiates, amphetamines, and other substances such as MDMA (ecstasy) and methamphetamine. However, it is important to note that the Marquis test is not a definitive test and can produce false positives or false negatives.