397 Microcrystal Analysis of Cocaine Hydrochloride and Added Adulterants

Friday, November 6, 2009: 9:45 AM
Kohlberg (Camino Real Hotel)
Hannah Nelson, Graduate Student , Department of Justice Sciences, University of Alabama at Birmingham, Birmingham, AL
Elizabeth Gardner , Department of Justice Sciences, University of Alabama at Birmingham, Birmingham, AL
Microcrystal analysis of drugs is a presumptive test that has gradually been replaced with more sophisticated technology.  However, these tests still have a place in forensic labs.  The objective of this project was to investigate the changes in the crystal morphology of cocaine in the presence of the common adulterants.  The most common microcrystal tests for cocaine uses gold chloride reagent to form a distinctive cross shape crystal with branches perpendicular to the axis.  Samples of cocaine with caffeine and lidocaine at 10, 20, and 50% concentration were prepared and examined under a polarized microscope.

The results indicate that the cocaine crystal morphology does change in the presence of an adulterant.  Distinct trends were observed with each adulterant at each concentration.  Similar trends were seen for aqueous and powder samples.  Cocaine/caffeine mixtures can be identified by the appearance of curved short axes.  The degree of curvature increases with caffeine concentration, until at 50% caffeine, sphere shaped branched crystals appear.  The crystal formation was also delayed in the presence of caffeine.

Unlike caffeine, the changes in crystal morphology of cocaine in the presence of lidocaine were seen immediately. Lidocaine adulterant can be identified by longer, thinner crystals with an X-shaped short axis.  As the lidocaine concentration increases, the crystals become x-shaped and at 50% lidocaine, the crystal form an X with the presence of few non-branched spherical crystals.

Current work on this project includes examining the crystal habit of cocaine mixtures of procaine, benzocaine, table sugar, baking soda, and levamisole.