"A drug’s metabolite is the compound produced when the body processes a particular drug. Identifying these compounds is the focus of workplace drug testing analysis. Marijuana possesses the greatest total number of detectable metabolites at 31 but fewer major components. For amphetamines, no metabolites are identified because these substances normally pass through the body essentially unchanged in chemical structure."
Source
"Drug Retention Times," Prepared for US Dept. of Energy Office of Security Policy, by the Center for Human Reliability Studies (Oak Ridge, TN: Oak Ridge Institute for Science and Education, May 2007), p. 1.
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