Development of a combined DNA and drug extraction methodology for forensic toxicology application

Kashkary, Loay M. T.

Abstract

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.

Citation

Kashkary, L. M. T. Development of a combined DNA and drug extraction methodology for forensic toxicology application. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4217177

• Thesis Type: Thesis
• Deposit Date: Oct 8, 2015
• Publicly Available Date: Feb 23, 2023
• Keywords: Chemistry
• Public URL: https://hull-repository.worktribe.com/output/4217177
• Additional Information: Department of Chemistry, The University of Hull
• Award Date: Aug 1, 2014