Pabalala Mthembi | University of the Free State (original) (raw)
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Papers by Pabalala Mthembi
Forensic Science International, 2018
Nyaope, a street drug commonly found in South Africa, is a mixture of low grade heroin, cannabis ... more Nyaope, a street drug commonly found in South Africa, is a mixture of low grade heroin, cannabis products, antiretroviral drugs and other materials added as cutting agents. It is a highly physiologically addictive substance which is smoked by users. Little work has been published on the chemical analysis and profiling of nyaope. Sample preparation prior to chromatographic or spectrometric analysis normally involves dissolution of the sample in an organic solvent. This study determined the most suitable organic solvent in which the common components of nyaope, namely D 9-tetrahydrocannabinol, diamorphine, caffeine, dextromethorphan, phenacetin and the antiretrovirals efavirenz and nevirapine, which have different chemical characteristics, are stable during extraction and prior to analysis of nyaope samples i.e. autosampler stability. Street samples of cannabis (D 9-tetrahydrocannabinol), heroin (diamorphine) and antiretrovirals were mixed to mimic a nyaope sample and dissolved in the organic solvents dichloromethane, ethanol, ethyl acetate, hexane, isopropanol and tertiary butyl alcohol. Analysis was performed after intervals of 0, 1, 6, 8, 24, 48 and 72 h, prior to analysis by gas chromatography-mass spectrometry. Tertiary butyl alcohol resulted in the most stable extracts of the main nyaope components after 72 h of storage. The analysis was also repeated on actual street samples of nyaope. These results show that tertiary butyl alcohol is a suitable solvent for sample preparation for the identification, comparison and profiling of nyaope samples.
South African Journal of Science
Nyaope, a Tswana word for a mixture or ‘mish-mash’, describes a drug cocktail consisting of heroi... more Nyaope, a Tswana word for a mixture or ‘mish-mash’, describes a drug cocktail consisting of heroin, cannabis, and on occasion other controlled substances and warfarin. It is highly addictive with extremely unpleasant side effects caused by withdrawal from the drug. It is a problem drug especially in townships in South Africa. However, its prevalence in neighbouring southern African states and further afield is not yet known. There is currently no validated method for the analysis and comparison of nyaope. We describe a validated method for the gas chromatography – mass spectrometry analysis of nyaope so that within-batch and between-batch comparisons of nyaope can successfully be made for the first time. The validated method managed an accuracy within the range 80–120%, the precision was less than 20% for all analytes and managed linearity with R2≥0.99. The detection limits for diamorphine, efavirenz, nevirapine and Δ9-tetrahydrocannabinol were 14.2, 18.6, 18.7 and 9.94 pg on column...
Forensic Science International, 2018
Nyaope, a street drug commonly found in South Africa, is a mixture of low grade heroin, cannabis ... more Nyaope, a street drug commonly found in South Africa, is a mixture of low grade heroin, cannabis products, antiretroviral drugs and other materials added as cutting agents. It is a highly physiologically addictive substance which is smoked by users. Little work has been published on the chemical analysis and profiling of nyaope. Sample preparation prior to chromatographic or spectrometric analysis normally involves dissolution of the sample in an organic solvent. This study determined the most suitable organic solvent in which the common components of nyaope, namely D 9-tetrahydrocannabinol, diamorphine, caffeine, dextromethorphan, phenacetin and the antiretrovirals efavirenz and nevirapine, which have different chemical characteristics, are stable during extraction and prior to analysis of nyaope samples i.e. autosampler stability. Street samples of cannabis (D 9-tetrahydrocannabinol), heroin (diamorphine) and antiretrovirals were mixed to mimic a nyaope sample and dissolved in the organic solvents dichloromethane, ethanol, ethyl acetate, hexane, isopropanol and tertiary butyl alcohol. Analysis was performed after intervals of 0, 1, 6, 8, 24, 48 and 72 h, prior to analysis by gas chromatography-mass spectrometry. Tertiary butyl alcohol resulted in the most stable extracts of the main nyaope components after 72 h of storage. The analysis was also repeated on actual street samples of nyaope. These results show that tertiary butyl alcohol is a suitable solvent for sample preparation for the identification, comparison and profiling of nyaope samples.
South African Journal of Science
Nyaope, a Tswana word for a mixture or ‘mish-mash’, describes a drug cocktail consisting of heroi... more Nyaope, a Tswana word for a mixture or ‘mish-mash’, describes a drug cocktail consisting of heroin, cannabis, and on occasion other controlled substances and warfarin. It is highly addictive with extremely unpleasant side effects caused by withdrawal from the drug. It is a problem drug especially in townships in South Africa. However, its prevalence in neighbouring southern African states and further afield is not yet known. There is currently no validated method for the analysis and comparison of nyaope. We describe a validated method for the gas chromatography – mass spectrometry analysis of nyaope so that within-batch and between-batch comparisons of nyaope can successfully be made for the first time. The validated method managed an accuracy within the range 80–120%, the precision was less than 20% for all analytes and managed linearity with R2≥0.99. The detection limits for diamorphine, efavirenz, nevirapine and Δ9-tetrahydrocannabinol were 14.2, 18.6, 18.7 and 9.94 pg on column...