SOFT - TIAFT 1998 Scientific Session 3 Thursday October 8, 1998
Click Picture Buddha D. Paul, Lisa K. McWhorter, and Michael L. Smith

Division of Forensic Toxicology, Office of the Armed Forces Medical Examiner, Armed Forces Institute of Pathology, Rockville, MD 20850, USA and Navy Drug Screening Laboratory, Naval Air Station, Jacksonville, FL 32212, CA

When cocaine is smoked, methyl ecgonidine is formed and also consumed as a pyrolytic product. Methyl ecgonidine is then metabolized to a stable compound, ecgonidine, and excreted in urine. Ecgonidine is a zwitterion and highly water-soluble. A method was developed to quantitatively identify ecgonidine in urine. After initial separation of benzoylecgonine and methyl ecgonidine from urine at pH 5.5 ± 0.5 using a solid phase extraction (SPE) technique, the pH of the solution was readjusted to 2.0-3.0. The acidic solution reduced the dissociation of the carboxylic acid and improved the lipophilic and cationic character of ecgonidine. The compound was extracted from the solution with the SPE technique with a 89-99% yield. Ecgonidine was then detected as the tert-butyldimethylsilyl derivative by GC-MS. Quantitation was linear over the concentration range of 7-2000 ng/mL. Concentrations as low as 7 ng/mL can be detected by this procedure.

Ecgonidine was detected in 96% of benzoylecgonine positive urine specimens (n = 23) from a random drug testing program indicating smoking as the major route of cocaine administration. In all specimens, the amount of methyl ecgonidine, the parent pyrolytic compound, was extremely small compared to the amounts of ecgonidine suggesting that ecgonidine is a better marker for identifying ingestion of cocaine by smoking. Detection of ecgonidine in urine is an indication of active or knowing use of cocaine and can be used to refute innocent ingestion defenses.

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