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1. Why is it important to be able to accurately measure this type of drug? (2 marks)
Ans. Ecstasy is a psychoactive drug, it has different emotional effects. Case reports of heightened reactions and deaths associated with the drugs imply that some individuals are at an increasing risk of toxicity, which makes it significant to find out the concentrations of the drugs in biological system in the medical and judicial case.
2. Why is hair a useful component to analyse? (2 marks)
Ans. Hair analysis for drugs has been gaining popularity in various toxicological fields because the ingests drugs circulate in a person’s bloodstream and are deposited in the hair follicle and entrapped in the core of the hair shaft as it grows out from the follicle.
This makes the hair samples less invasive and easier to collect, store and dispatch compared to blood and urine samples.
3. What are the disadvantages to using hair as a sample? (2 marks)
Ans. The disadvantages of using hair as a sample are that the biological component is complex and analyte are usually present at low concentration in the body, therefore, the a pre-concentration and clean up of the sample must be carried out before analyte can be determined by high-performance liquid chromatography (HPLC) or gas chromatography (GC).
4. What does the extraction method in this paper involve? (3 marks)
Ans. The extraction techniques are used as the preparation method in the determination of drug residues by HPLC, GC, The measurement of ecstasy and capillary electrophoresis (CE). In this work a new sampling method termed ‘directly suspended droplet micro extraction (DSDME) was used, based on a three-phrase extraction system which is compatible with HPLC.
In triple phase DSDME the acceptor solution is an aqueous phase providing a three-phase system, where the analyte is extracted from an aqueous sample, through the thin layer of organic solvent and into an aqueous acceptor droplet.The measurement of ecstasy After the extraction, pre-concentrated analyte was directly introduced into HPLC for further analysis.
5. How was the stock MDMA diluted to make a standard of 5ug/ml? (3 marks)
Ans. Stock solution of MDMA was prepared by dissolving the 8.18 mg of tablet powder in 10 ml methanol. Standard sample containing MDMA at 5.0 µg mL-1 was provide by dilution of stock solution in de-ionized water. They were stored at 4± 0.5 °C.
6. What were the components of the mobile phase? ( 1 mark)
Ans. The components were water, acetonitrile and methanol.
7. How could you prepare a 5mL solution of the mobile phase? (2 marks)
Ans. The mobile phase, optimized on (80:15:5,v/v), was degassed by own system degasser and delivered two pumps S1000. The flow rate of the mobile phase was 0.8 mL min -1 and UV detection wavelength was set as 254 nm.
8. What were the HPLC conditions? What part of the spectrum can Ecstasy be detected? (2 marks)
Ans. The binary HPLC system used in this work was a knauer containing UV-detector S2600, a port sample injection valves equipped with a 20-µL loop. Separation was accomplished using a 100/5-RP-18 column with 4.6 mm diameter, 250 mm length.
9. What samples were used as negative and positive controls? (1 mark)
Ans. The sample used as positive controls was a bulk of blank hair without esctacy and negative control was hair with ecstasy.
10. What disadvantages are there to consider when analysing hair for this purpose and how was this overcome? (2 marks)
Ans. The disadvantage is the possibility that a drug has been incorporated in hair from external sources and not by consumption.The measurement of ecstasy So before analysis of hair samples a decontamination strategy has to be performed and washing solutions. The hair was washed with different solvents at room temperature and then it was dried.
11. Why were different solvents used to wash the hair in and what was the solvent used to extract MDMA (2 marks)
Ans. Different solvents were used as liquid-liquid- liquid micro extraction technique. MDMA was extracted from MDMA aqueous solution.
12. What were the names of organic the 3 solvents used in this investigation? (1 mark)
Ans. Toluene, n-hexane and 1-octanol
13. Draw their structures here. (3 marks)
Toluene
n-hexane
1-octanol
14. Which was the best solvent to use and why? (1 mark)
Ans. 1-octanol was used because of its high viscosity and other suitable characteristics.
15. What was the effect of stirring rate on the enrichment factor? (2 marks)
Ans. Stirring speed is a major factor that affects the extraction efficiency. Increasing the stirring rate can decrease the thickness of the diffusion film in the aqueous phase and improve the repeatability the extraction method. Thus, enrichment factor is better…
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