The signature patterns of cocaine samples were examined by capillary gas chromatography using 14 impurities commonly found in illicit cocaine samples. The procedure is based on acidic, basic, and neutral impurities introduced from the coca plant and from the processing of cocaine in clandestine laboratories. Impurities containing either alcoholic, N-nor, or carboxylic acid functional groups were analyzed as their silyl derivatives. The reported procedure provides a simple one-step assay for obtaining chromatographic impurity signature profile analyses (CISPA) of illicit cocaine samples using flame ionization detection (FID).
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 13 C and 15 N 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 δ 13 C values than the original morphine. There was an isotopic fractionation against 15 N 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 δ 13 C 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 δ 13 C values of the acetic anhydride from deacetylated heroin δ 13 C values.
Illicit cocaine laboratories in South America have been adding phenyltetrahydroimidazothiazole enantiomers (levamisole and/or tetramisole) to refined illicit cocaine for over 8 years. A chiral capillary gas chromatographic methodology is presented for phenyltetrahydroimidazothiazole enantiomer determination in illicit cocaine samples and in the urine of cocaine abusers. Illicit cocaine samples (N = 752) and urine specimens from cocaine abusers (N = 50) that contained phenyltetrahydroimidazothiazole were analyzed for enantiomeric composition. Legitimate commercial preparations of phenyltetrahydroimidazothiazole are either 100% levamisole or a 50:50 mixture of levamisole and dexamisole (tetramisole). Specimens that contain phenyltetrahydroimidazothiazole mixtures that are other than 50:50 preparations will be enhanced in one isomer over the other, and they are referred to as either "levamisole-enhanced" or "dexamisole-enhanced". Cocaine samples were found to contain levamisole (N = 495, 66%), tetramisole (N = 143, 19%), and levamisole-enhanced enrichment (N = 114, 15%); urine specimens contained levamisole (N = 23, 46%), levamisole-enhanced enrichment (N = 10, 20%), and dexamisole-enhanced enrichment (N = 13, 26%). The toxicological and forensic aspects of these findings are discussed.
In this study, various anionic chiral selectors were investigated for the capillary electrophoresis (CE) separation of six chiral phenethylamines and three achiral neutral impurities which are commonly identified in illicit methamphetamine. Analyses were carried out at pH 8 (high osmotic flow) with untreated capillaries using 25 mM chiral surfactant or 10 mM charged cyclodextrin. The chiral selectors included the micelle (R)-N-dodecoxycarbonylvaline (EnantioSelect (R)-Val-1) (ES) and the cyclodextrins sulfobutyl(IV)-ether-beta-cyclodextrin (SBE(IV)-beta-CD) (BSB4), SBE(VII)-beta-CD (BSB7), SBE(XII)-beta-CD (BSB 12), SBE(IV)-gamma-CD (GSB-4), SBE(VII)-gamma-CD (GSB-7), sulfated(XI)-alpha-cyclodextrin (SU(XI)-alpha-CD (AS11), SU(VII)-beta-CD (BS7), SU(XII)-beta-CD (BS12) and SU(XIII)-beta-CD (GS13). Enantiomeric and achiral selectivity strongly depends on the size of the CD, the average degree of substitution, and the type of substitution. ES exhibits good performance for the neutral solutes, but exhibits enantiomeric selectivity only for the alpha-hydroxyphenethylamines. GS13 provides the best overall enantiomeric selectivity. All fifteen solutes related to methamphetamine are simultaneously separated using BSB7.
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