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Title: Development of a combined DNA and drug extraction methodology for forensic toxicology application
Author: Kashkary, Loay M. T.
ISNI:       0000 0004 5365 7380
Awarding Body: University of Hull
Current Institution: University of Hull
Date of Award: 2014
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Biological samples recovered at crime scenes may contain unsuspected and valuable evidence, such as illicit drugs, in addition to nucleic acids. Deoxyribonucleic acid (DNA) analysis provides valuable information to identify a suspect or victim, as well as to exclude an innocent individual as the perpetrator of a crime. Identification of drugs can also be very informative for forensic investigation to determine whether a perpetrator committed a crime under the influence of illicit substances. In the field of forensic analysis, sample preparation for identifying both DNA and drugs of abuse represents a challenge due to limited sample quantity and only trace levels of target analytes present in the matrices. As a result, an analytical approach has been developed to enable the combined extraction of DNA and four amphetamines (amphetamine [AM], methamphetamine [MA], 3,4-methylenedioxyamphetamine [MDA], and 3,4-methylenedioxymethamphetamine hydrochloride [MDMA]) from a small amount of sample (50 μl) using a single extraction procedure. This study has focused on solid-phase extraction (SPE) using inorganic silica-based matrices as sorbents to facilitate such sample processing. The advantages of using inorganic silica-based monoliths are due to the simple fixation of the material in a column or within a microfluidic device, their mechanical stability with organic solvents, the availability of simple surface modifications to enable the desired chemical interaction with the target molecules, and a unique bimodal structure that allows a large surface area with minimum back pressure. A dual-phase SPE method was developed consisting of silica beads modified with octadecyl groups packed inside a luer lock adapter for amphetamine extraction coupled in series with a silica-based monolith for DNA extraction within a microfluidic system for a fully combined genetic and drug extraction system. The proposed method was effective for the extraction of the target drugs from a spiked buffer and artificial urine giving an average recovery greater than 70% and 50%, respectively, with high reproducibility (˂ 15% RSD). The limits of detection were 0.6 μg ml⁻¹ for AM and MA, 0.7 μg ml⁻¹ for MDA, and 0.8 μg ml⁻¹ for MDMA with linear calibration curves between 0.625 and 20 μg ml⁻¹. The method was also able to extract DNA from the spiked TE buffer and urine sample with average extraction efficiencies of 36% and 30%, respectively, which were successfully amplified via the polymerase chain reaction (PCR). The proposed method is not only suitable for the combined extraction of DNA and amphetamines from a limited sample size, but also reduces sample handling and potential contamination. This method could, in future, be applied to anti-doping analysis for the detection of doping agents and conducting DNA profiling as evidence to ascertain whether samples belong to the right athletes.
Supervisor: Haswell, S. J.; Greenway, Gillian; Pamme, Nicole Sponsor: Government of Saudi Arabia
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Chemistry