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Quantitative Determination of Cocaine in Illicit Powders by Free Zone Capillary Electrophoresis

NCJ Number
Journal of Forensic Sciences Volume: 43 Issue: 4 Dated: July 1998 Pages: 738-743
A S Krawczeniuk; V A Bravenec
Date Published
6 pages
A free-zone capillary electrophoresis (CE) method was developed to quantify cocaine in illicit powder, based on the use of a sodium phosphate-sodium borate buffered system to separate the most common cocaine adulterants and impurities.
Cocaine samples were introduced using hydrodynamic pressure injection for 3 seconds. The running buffer consisted of sodium monobasic phosphate and sodium borate. The buffer was filtered and degassed with sonication prior to use. The capillary was flushed with running buffer for 2 minutes between sample runs. For quantitation, a standard solution of cocaine was prepared by dissolving a known amount of hydrochloride sale in an appropriate volume of histamine diphosphate internal standard solution. A finely ground sample was dissolved in an appropriate volume of stock internal standard solution to give a concentration equal to the standard cocaine hydrochloride area concentration. Results showed that CE offered a highly efficient and selective alternative to traditional chromatographic techniques. CE was capable of providing quantitative data on illicit cocaine seizures that were comparable to those obtained by previously validated gas-liquid chromatography. Separation was reproducible from capillary to capillary over a 1-year period. CE offered the added benefits of low solvent consumption, minimal sample size requirements, and short analysis times, all of which may be valuable to high- production forensic laboratories. 20 references, 6 tables, and 2 figures


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