Doctoral Degrees (Genetics)
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Browsing Doctoral Degrees (Genetics) by Subject "Drugs -- Chemistry"
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Item Open Access Chemical profiling of the street cocktail drug ‘nyaope’ in South Africa using gas chromatography-mass spectrometry (GC-MS)(University of the Free State, 2020) Mthembi, Pabalala Meshack; Mwenesongole, E. M.; Cole, M. D.; Grobler, J. P.𝑬𝒏𝒈𝒍𝒊𝒔𝒉 The street cocktail drug nyaope, commonly found in South Africa, is a mixture of low-grade heroin, cannabis products, antiretroviral drugs and other materials added as bulking agents. This research led to the development of an analytical method for the identification and profiling of the street cocktail drug nyaope, using gas chromatography – mass spectrometry. This study determined for the first time the most suitable organic solvent in which the common components of nyaope, namely Δ9-tetrahydrocannabinol, heroin, caffeine, dextromethorphan, phenacetin and the antiretrovirals efavirenz and nevirapine, which have different chemical characteristics, are stable prior to an analysis of nyaope samples. The main nyaope components, when extracted into tertiary butyl alcohol, exhibited the greatest autosampler stability of up to 72 hours of storage. From these results it can be determined that tertiary butyl alcohol is a suitable solvent for the identification, comparison and profiling of nyaope samples. With regard to analytical method validation, the method gave acceptable repeatability with the %RSD less than 10% for the 10.0 and 1000.0 mg/L concentration levels for the majority of the components. The linear concentration ranges managed linearity with r2 ≥ 0.997. The detection limits varied between 9.90–39.0 pg on column and the limit of quantitation between 30.0–120 pg on column. The method exhibited acceptable recoveries and ruggedness. The method developed is fit for the purpose of quantitative profiling of the major components of nyaope using gas chromatography-mass spectrometry. The majority of the components in the street cocktail drug nyaope were shown to be stable up to at least 24 hours when stored in a refrigerator. For profiling purposes, samples need to be extracted within 24 hours of seizure in a solvent in which they are stable, such as tertiary butyl alcohol and analysed within 72 hours. At all times the samples need to be protected from light to prevent the photo-decomposition of Δ9-tetrahydrocannabinol and from moisture to prevent the hydrolysis of diamorphine. The chemical components of simulated nyaope samples as well as actual seized street nyaope samples were successfully identified and quantitatively determined using gas chromatography – mass spectrometry. The simulated and actual seized street samples were successfully discriminated into original batches using the identified nyaope components and two unsupervised chemometric methods, namely principal component analysis and hierarchical clustering, as well as chromatographic profiles. Thus, for the first time, a validated analytical method has been developed for the identification, quantitation and profiling of nyaope using gas chromatography – mass spectrometry. The method will assist law enforcement agencies in the identification and comparison of nyaope samples and facilitate the prosecution of illicit drug trafficking offences. ___________________________________________________________________