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theses

Microcrystal tests have been used in chemical identification for over 150 years. The tests involve the addition of a crystallizing reagent to a test sample followed by the microscopic observation of characteristic crystals. While this technique predates modern instrumental techniques of chemical analysis, it still has several distinct advantages. Microcrystal tests are rapid, inexpensive, and fairly simple to perform. However, this technique suffers from several criticisms due to the lack of atomic-level structural data from the resulting crystals. The crystallizing reagent, 5% chloroauric acid prepared from gold(III) chloride in water or dilute hydrochloric acid, is one of the most common reagents used in forensic laboratories in the analysis of suspected drug substances. The crystals precipitating from the reaction of this reagent and illicit substances from three categories of drugs were examined by single crystal X-ray diffraction. Cocaine is one of the most widely abused drugs, worldwide. Cocaine produces well characterized microcrystals upon mixing with the gold (III) chloride reagent. Ecgonine, the final stable metabolite of cocaine, is structurally similar to the parent drug and also forms crystals when reacted with gold (III) chloride. The gold (III) chloride salts of cocaine and ecgonine (hydrated and anhydrous) and the hydrochloride salt of ecgonine were determined and compared by single crystal X-ray diffraction. Single crystals precipitated from the addition of gold chloride test reagent to several structurally similar phenethylamines: amphetamine, methamphetamine, and ephedrine. While all of the other drugs of this category formed salts with the gold chloride anion, amphetamine was the only compound to bind covalently to the gold atom, displacing two chlorides. In recent years, various cathinone-derived drug products have entered the illicit drug market. Ethylone, α-PVP, pentylone, dibutylone, ephylone, and 3,4-methyl¬ene¬dioxy¬pyrovalerone (MDPV) were analyzed by single crystal X-ray diffraction in various salt forms, including the product of the gold chloride crystal test with MDPV. While the use of gold (III) chloride as a crystal precipitating agent is well-established, it is expensive and does not always form crystals with certain drug compounds. The novel application of Erdmann’s salt as a crystal precipitating reagent was successfully tested with a representative candidate from each of the previously described classes and the resulting crystals were structurally characterized.

ETD_8157

Ph.D.

Includes bibliographical references

by Matthew R. Wood

doi:10.7282/T34Q7XXH

ETD doctoral

The author owns the copyright to this work.