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Methyl Esters of Ecgonine: Injection-Port Produced Artifacts From Cocaine Base (Crack) Exhibits

NCJ Number
Journal of Forensic Sciences Volume: 37 Issue: 5 Dated: (September 1992) Pages: 1295-1310
Date Published
16 pages
This paper discusses the formation of ecgonine methyl ester and pseudoecgonine methyl ester as artifacts in gas chromatography/mass spectrometry (GC/MS) analysis of cocaine base exhibits containing traces of sodium bicarbonate.
Many cocaine base (crack) exhibits contain traces of sodium bicarbonate. Pseudoecgonine methyl ester and ecgonine methyl ester are formed as artifacts from the effect of sodium bicarbonate and methanol in the injection port of a gas chromatograph. The formation of ecgonine methyl esters was confirmed by comparison to known standards via GC/MS. Mechanisms for artifact formation were hydrolysis of cocaine, followed by esterification and transesterification/base catalyzed epimerization. The formation of anhydroecgonine methyl ester as an artifact via thermal elimination of benzoic acid from cocaine was also supported by the experimental data. It was determined that artifacts produced by GC or sample preparation must always be considered when identifying natural products. Extractions or solvents may inadvertently promote certain artifacts because of their physical and chemical properties. 11 references and 12 figures

Date Published: January 1, 1992