Chemical composition The main psychoactive component of<unk> is THC, which is formed via decarboxylation of THCA from the application of heat. Raw leaf is not psychoactive because the<unk> oids are in the form of carboxylic acids.<unk> oids Detection in body fluids THC and its major (inactive) metabolite, THC-COOH, can be measured in blood, urine, hair, oral fluid or sweat using chromatographic techniques as part of a drug use testing program or a forensic investigation of a traffic or other criminal offense. The concentrations obtained from such analyses can often be helpful in distinguishing active use from passive exposure, elapsed time since use, and extent or duration of use. These tests cannot, however, distinguish authorized<unk> smoking for medical purposes from unauthorized recreational smoking. Commercial<unk> oid immunoassays, often employed as the initial screening method when testing physiological specimens for marijuana presence, have different degrees of cross-reactivity with THC and its metabolites. Urine contains predominantly THC-COOH, while hair, oral fluid and sweat contain primarily THC. Blood may contain both substances, with the relative amounts dependent on the recency and extent of usage. The Duquenois–Levine test is commonly used as a screening test in the field, but it cannot definitively confirm the presence of<unk>  as a large range of substances have been shown to give false positives. Researchers at John Jay College of Criminal Justice reported that dietary zinc supplements can mask the presence of THC and other drugs in urine. However, a 2013 study conducted by researchers at the University of Utah School of Medicine refute the possibility of self-administered zinc producing false-negative urine drug tests.
Cannabis 
Heroin
Cocaine
Cocaine 
Benzyl alcohol
Phencyclidine
Methamphetamine
Nicotine