Document Type
Dissertation
Degree
Doctor of Philosophy (PhD)
Major/Program
Chemistry
First Advisor's Name
Bruce McCord
First Advisor's Committee Title
Committee Chair
Second Advisor's Name
Jose Almirall
Second Advisor's Committee Title
Committee Member
Third Advisor's Name
Jaroslava Miksovska
Third Advisor's Committee Title
Committee Member
Fourth Advisor's Name
Fenfei Leng
Fourth Advisor's Committee Title
Committee Member
Fifth Advisor's Name
Chenzhong Li
Fifth Advisor's Committee Title
Committee Member
Keywords
SERS, Benzodiazepines, Forensic Science
Date of Defense
11-14-2014
Abstract
Benzodiazepines are among the most prescribed compounds for anti-anxiety and are present in many toxicological screens. These drugs are also prominent in the commission of drug facilitated sexual assaults due their effects on the central nervous system. Due to their potency, a low dose of these compounds is often administered to victims; therefore, the target detection limit for these compounds in biological samples is 10 ng/mL. Currently these compounds are predominantly analyzed using immunoassay techniques; however more specific screening methods are needed.
The goal of this dissertation was to develop a rapid, specific screening technique for benzodiazepines in urine samples utilizing surface-enhanced Raman spectroscopy (SERS), which has previously been shown be capable of to detect trace quantities of pharmaceutical compounds in aqueous solutions. Surface enhanced Raman spectroscopy has the advantage of overcoming the low sensitivity and fluorescence effects seen with conventional Raman spectroscopy. The spectra are obtained by applying an analyte onto a SERS-active metal substrate such as colloidal metal particles. SERS signals can be further increased with the addition of aggregate solutions. These agents cause the nanoparticles to amass and form hot-spots which increase the signal intensity.
In this work, the colloidal particles are spherical gold nanoparticles in aqueous solution with an average size of approximately 30 nm. The optimum aggregating agent for the detection of benzodiazepines was determined to be 16.7 mM MgCl2, providing the highest signal intensities at the lowest drug concentrations with limits of detection between 0.5 and 127 ng/mL. A supported liquid extraction technique was utilized as a rapid clean extraction for benzodiazepines from urine at a pH of 5.0, allowing for clean extraction with limits of detection between 6 and 640 ng/mL. It was shown that at this pH other drugs that are prevalent in urine samples can be removed providing the selective detection of the benzodiazepine of interest.
This technique has been shown to provide rapid (less than twenty minutes), sensitive, and specific detection of benzodiazepines at low concentrations in urine. It provides the forensic community with a sensitive and specific screening technique for the detection of benzodiazepines in drug facilitated assault cases.
Identifier
FI14110743
Recommended Citation
Doctor, Erika L., "Development of a Surface-Enhanced Raman Spectroscopy Method for the Detection of Benzodiazepines in Urine" (2014). FIU Electronic Theses and Dissertations. 1642.
https://digitalcommons.fiu.edu/etd/1642
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