Tropane Ethyl Esters in Illicit Cocaine: Isolation, Detection, and Determination of New Manufacturing By‐Products from the Clandestine Purification of Crude Cocaine Base with Ethanol

  Seven ethyl homologues of known tropane esters have recently been detected as impurities in the gas chromatographic signature profiles of authentic Peruvian illicit cocaine base and hydrochloride exhibits. Peruvian cocaine base processors are now known to use ethanol for the purification of crude cocaine base. This process is referred to as the “ base lavada ” or “washed base” process and is a recent substitute method for the potassium permanganate oxidation purification methodology. Seven ethyl ester homologues were formed in illicit cocaine from the transesterification of known tropane methyl esters or possibly ethyl esterification of their respective tropane C‐2 carboxylic acids in the presence of ethanol. Exhibits containing these compounds were subjected to gas chromatographic‐mass spectrometric analyses to determine their identity and were subsequently synthesized to verify their structures. Quantitative determinations were obtained from ion‐pair chromatography isolation followed by gas chromatography with flame ionization detection. Specifically, hexanoylecgonine ethyl ester, cocaethylene, cis ‐cinnamoylecgonine ethyl ester, trans ‐cinnamoylecgonine ethyl ester, 3′,4′,5′‐trimethoxybenzoylecgonine ethyl ester, cis ‐3′,4′,5′‐trimethoxycinnamoylecgonine ethyl ester, and trans ‐3′,4′,5′‐trimethoxycinnamoylecgonine ethyl ester were detected and characterized. When present, these compounds were detected at levels ranging from 8.6 × 10 −4 to 9.3 × 10 −1 % relative to cocaine.