Tosylethyl-PE2I is a compound synthesized from Ecgonidine Methyl Ester (E325300) which is a metabolite of Cocaine (COC). Ecgonidine Methyl Ester is a pyrolysis product formed when crack cocaine is smoked, making this substance a useful biomarker to specifically test for use of crack cocaine, as opposed to powder cocaine which does not form methylecgonidine as a metabolite.