Date of Degree

5-2019

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

John Lombardi

Committee Members

Louis Massa

Glen Kowach

Subject Categories

Analytical Chemistry | Applied Statistics | Contemporary Art | Materials Chemistry | Modern Art and Architecture

Keywords

Raman, SERS, Forensics, Opioids, Cultural Heritage, Pigments

Abstract

Raman spectroscopy is an effective tool for detecting trace amounts of material by fingerprint-like vibrational spectra. At times, the weak intensity of Raman scattering can make it difficult to distinguish trace materials. This shortcoming is addressed by surface‐enhanced Raman spectroscopy (SERS), which produces strong signal enhancements when target compounds are near metal nanoparticles. For the first part of this thesis, the identification of fentanyl and carfentanil, main culprits in the opioid epidemic, was done using normal Raman and the SERS spectroscopy. As an aid in the assignment of the spectral lines, a computational model was built using Density Functional Theory (DFT). The enhancement factor (EF) obtained in this experiment is ≥ 1.6 x 105. The use of a paper-based substrate impregnated with silver nanoparticles for the detection of trace quantities of fentanyl alone, and as an adulterant in heroin and cocaine, was investigated. In addition, intensity ratios of diagnostic peaks associated with each substance were fitted to a Langmuir isotherm calibration model and used for quantitative analysis of fentanyl in heroin mixtures. Linearity was observed at < 6% fentanyl, a significant finding that is consistent with concentrations found in drugs seized during law enforcement efforts. For trace quantities of fentanyl in cocaine, where it identified at a lower limit of 500 ng/mL in mixtures. Linear relationships were established between intensity and concentration for diagnostic peaks associated with fentanyl and cocaine. For the second part of this thesis, the applicability of normal Raman and SERS are presented in the context of a museum setting. The applicability of confocal and portable Raman is presented through the identification of : red pigments found in El Anatsui’s Bleeding Takari II; identification of the gouaches used by Henri Matisse in the Jazz album; and identification of the paints used by Jackson Pollock in Number 1A, 1948.

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