Faculty of Natural and Agricultural Sciences
School of Physical Sciences
Department of Chemistry
Selected Highlights from Research Findings
Amphetamine and related derivatives are widely abused central nervous system stimulants. Detection of certain derivatives, such as methcathinone (“Cat”) in the urine of suspected abusers by commonly available preliminary immunoassay testing is insufficient. The use of legal over-the-counter medication is well known to be a cause of false positive preliminary drug testing results. Multi-analyte confirmations for amphetamine derivatives are therefore required. However, traditional analytical methods necessitate lengthy procedures with prolonged sample turnaround times. A short turnaround time is of prime importance in the case of persons held in custody and other clinical and forensic toxicology applications, like workplace drug testing.
A validated rapid GC-MS assay for urinary confirmation of nine of the most commonly used amphetamine derivatives, including methamphetamine (“Tik”) and methcathinone, has been reported by Dr Johannes Laurens and Mr Adriaan Marais of the Department of Chemistry. The method entailed in-situ derivatisation of urine samples by extractive acylation, followed by a rapid chromatographic separation and mass spectrometric detection. All nine amphetamine derivatives were separated in less than three minutes and quantified simultaneously by selected-ion monitoring using stable isotope substituted internal standards. The total instrument cycle time is six minutes per sample, allowing 200 confirmatory analyses per day on one instrument. The limits of detection, precision and accuracy are within acceptable limits for forensic court evidence. This method has been employed successfully for the amphetamine derivative confirmations in urine since 2008 in the Forensic Toxicology Laboratory in the Department of Chemistry.
Contact person: Dr JB Laurens.
Amphetamine and related derivatives are widely abused central nervous system stimulants. Detection of certain derivatives, such as methcathinone (“Cat”) in the urine of suspected abusers by commonly available preliminary immunoassay testing is insufficient. The use of legal over-the-counter medication is well known to be a cause of false positive preliminary drug testing results. Multi-analyte confirmations for amphetamine derivatives are therefore required. However, traditional analytical methods necessitate lengthy procedures with prolonged sample turnaround times. A short turnaround time is of prime importance in the case of persons held in custody and other clinical and forensic toxicology applications, like workplace drug testing.
A validated rapid GC-MS assay for urinary confirmation of nine of the most commonly used amphetamine derivatives, including methamphetamine (“Tik”) and methcathinone, has been reported by Dr Johannes Laurens and Mr Adriaan Marais of the Department of Chemistry. The method entailed in-situ derivatisation of urine samples by extractive acylation, followed by a rapid chromatographic separation and mass spectrometric detection. All nine amphetamine derivatives were separated in less than three minutes and quantified simultaneously by selected-ion monitoring using stable isotope substituted internal standards. The total instrument cycle time is six minutes per sample, allowing 200 confirmatory analyses per day on one instrument. The limits of detection, precision and accuracy are within acceptable limits for forensic court evidence. This method has been employed successfully for the amphetamine derivative confirmations in urine since 2008 in the Forensic Toxicology Laboratory in the Department of Chemistry.
Contact person: AAS Marais.
At the start of 2009, the first group of students who were taught exclusively according to outcomes-based education and the new curricula for science and mathematics in public schools entered tertiary education. During the past seven years, a research project has been conducted by Prof Marietjie Potgieter to monitor the proficiencies of first-year Chemistry students upon entry to tertiary education. This project enabled the Department of Chemistry to make a rigorous assessment of the shifts that occurred in the preparedness of students following the extensive revision of secondary education. The mismatch between the Grade 12 performance rating scales used in the former dispensation and those used in the current National Senior Certificate was quantified. The study showed that while content topics explicitly taught and assessed in Grade 12 were mastered to a similar extent as before, students were significantly less well prepared in terms of the development of skills such as mathematical competency and logical reasoning. A number of basic concepts such as acids and bases and the mole concept were also poorly mastered. These results were widely communicated to chemistry lecturers at South African universities, as well as to the Department of Higher Education and Training so that deficiencies could be addressed in a constructive manner.
Contact person: Dr M Potgieter.
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