Isotopic fractionation of carbon and nitrogen during the illicit processing of cocaine and heroin in South America
CasaleJ
Special Testing and Research Laboratory, Drug Enforcement Administration, U.S. Department of Justice, Dulles, VA

EhleringerJ
Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, Salt Lake City, UT

MorelloD
Special Testing and Research Laboratory, Drug Enforcement Administration, U.S. Department of Justice, Dulles, VA

LottM
Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, Salt Lake City, UT

(Received 18 February 2005; Accepted 14 May 2005)

Abstract
The forensic application of stable isotope analysis to cocaine and heroin for geolocation of exhibits must take into account the possible enrichment and/or depletion of ¹³C and ¹⁵N during the illicit manufacturing process. Continuous-flow elemental analysis-isotope ratio mass spectrometry was utilized to measure changes in the stable isotope ratios of carbon and nitrogen for both cocaine (N=92) and heroin/morphine (N=81) exhibits derived from illicit manufacturing processes utilized by South American clandestine chemists. In controlled settings in South America, there was no siginficiant carbon isotope fractionation during the conversion of cocaine base to cocaine HCl using current illict methodologies. In contrast, nitrogen isotope fractionation for this conversion was 1‰. There was a kinetic carbon isotope ratio fractionation during the acetylation of Colombian morphine to heroin and as a result heroin exhibits will almost always have more negative d¹³C values than the original morphine. There was an isotopic fractionation against ¹⁵N during the acetylation of morphine base to heroin base, but this effect was not expressed since all of the heroin base was precipitated during the manufacturing process. However, the clandestine process of converting a single batch of heroin base usually involved two consecutive crops of heroin HCl and the latter crop was isotopically depleted as expected from a Rayleigh distillation process. When heroin was deacetylated to morphine, the morphine produced resulted in d¹³C values that were indistinguishable from the original morphine. The kinetic carbon isotope fractionation factor for the South American process of morphine acetylation was -1.8‰, allowing calculation of the d¹³C values of the acetic anhydride from deacetylated heroin d¹³C values.

Keywords:
cocaine, drug origin, elemental analysis, forensic science, geosourcing, heroin, isotopic analysis, kinetic fractionation, Rayleigh fractionation, stable isotope ratio mass spectrometry

Paper ID: JFS2005077
DOI: 10.1520/JFS2005077

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Author Casale JF, Ehleringer JR, Morello DR, Lott MJ Title Isotopic fractionation of carbon and nitrogen during the illicit processing of cocaine and heroin in South America Symposium , Committee on