Browsing by Author "Simasiku, Bronah N."

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    Development of a low volume dispersive liquid-liquid microextraction method for the simultaneous determination of illicit psychoactive drugs used by motorists in the Khomas region of Namibia
    (University of Namibia, 2016) Simasiku, Bronah N.
    In recent years, there has been an increase in fatal road accidents in Namibia claiming many lives each year. Traffic accidents are often related to the use of alcohol, illegal drugs or psychoactive medicines. A rapid low volume dispersive liquid-liquid microextraction (DLLME) method in combination with gas chromatography-mass spectrometry (GC-MS) detection was developed for the simultaneous determination of illicit psychoactive drugs in blood (those used most commonly in Namibia: cocaine, Δ⁹- tetrahydrocannabinol, amphetamine and methamphetamine). Various DLLME parameters were optimised to improve the extraction efficiency of the analytes. The method was successfully applied for the simultaneous determination of the drugs from spiked blood in a single extraction with satisfactory sensitivity, accuracy, repeatability, linearity and recoveries. The limits of detection (LOD) for different drugs varied from 0.00001 to 0.055 μg/mL while the limits of quantification (LOQ) varied from 0.0001 to 0.1 μg/mL. The precision was in a range of 2-10 %. The method was linear in the ranges of 0.00001-10 μg/mL with the correlation coefficient (r2) ranging between 0.998-0.999. The recoveries of the analytes were between 84 and 103 %. The validated method was subsequently successfully applied in the screening of drugs in the blood collected from motorists (samples which were originally collected for blood-alcohol determination). The developed method utilised very low volumes of dispersion and extraction solvents (about 6 and 4 μL respectively) and only 25 μL of blood. Since the DLLME procedure was performed in 300 μL micro-insert GC vials, it was easier to collect the sedimented volume (containing the drugs) formed at the end of the extraction process with a GC injection needle without running the risk of mixing the separated layers. This solution was directly submitted to GC-MS analysis without any need for further treatment, e.g. evaporation and reconstitution, which significantly reduced the extraction time of the method. The method was also successfully automated with an Agilent Sample Prep Workbench 7696A. Due to these advantages, this method lends itself to be used in high throughput routine analysis of drugs and potentially other substances (e.g. of toxicological relevance) in trace amounts of blood.