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Title: Study of SERS for the detection of drugs of abuse
Author: Lamping, Sarah Louise
ISNI:       0000 0004 2668 6514
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2008
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A study of the use of Surface Enhanced Raman Spectroscopy (SERS) for the detection of illicit drugs in oral fluid using metal enhancement mechanisms was undertaken. Initial work investigated ecstasy tablet composition using Raman to identify what drugs and excipients might be present in oral fluid samples obtained from users. Overall, it is possible to identify the presence of phenethylamines and excipients in the seized tablets but not categorically distinguish between the phenethylamine derivative(s) especially when in a mixture. Comparison of the overall batch average peak positions and peak responses of the phenethylamine derivatives and excipients shows variability across the batches and reveals trends within the sub-batches. The Raman spectra appear to reflect the findings of the GUMS analysis tentatively, implying this technique could be used for initial intelligence gathering applications whilst confirmatory analysis results are awaited. Initial SERS research focused on achieving enhancement of aqueous drug solutions with silver and gold colloid. Overall a lack of reproducibility was observed. Therefore, alternative SERS enhancement mechanisms were sought. Ag/Ti0₂ substrates demonstrated low limits of detection and the possibility of detecting SERS enhancement of aqueous amphetamine solution at levels below 8x10⁻² M. The work also showed that cotton swabs for sample application onto the surface of the substrate are a viable practical option for both experimental and field analysis. Successful detection of methadone and buprenorphine, used to treat heroin addiction, was achieved with Ag/Ti0₂ substrates at concentrations associated with therapeutic use, representing lower concentration drugs. The detection of MDMA in oral fluid following ecstasy use, not only showed promise for the detection of illicit drugs, but did so at the analytical cut-off concentration detailed in the draft type approval specification for roadside drug screening devices. This work confirms that SERS has a role for drug detection in oral fluid samples.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral