TY - JOUR

T1 - Ab Initio Calculations and Raman and SERS Spectral Analyses of Amphetamine Species

A1 - Berg,Rolf W.

A1 - Nørbygaard,Thomas

A1 - White,Peter C.

A1 - Abdali,Salim

AU - Berg,Rolf W.

AU - Nørbygaard,Thomas

AU - White,Peter C.

AU - Abdali,Salim

PB - Taylor & Francis Inc.

PY - 2011

Y1 - 2011

N2 - For the first time, the differences between the spectra of amphetamine and amphetamine-H+ and between different conformers are thoroughly studied by ab initio model calculations, and Raman and surface-enhanced Raman spectroscopy (SERS) spectra are measured for different species of amphetamine. The spectra of amphetamine and amphetamine-H+ sampleswere obtained and assigned according to a comparison of the experimental spectra and the ab initio MO calculations, performed using the Gaussian 03W program (Gaussian, Inc., Pittsburgh, PA). The analyses were based on complete geometry minimization of the conformational energy of the S-plus-amphetamine molecule and the S-plus-amphetamine-H+ ion. The harmonic frequency calculations provide information about the characteristic features of the Raman spectra and the nature of the bonding in the molecule. It is concluded that vibrational bands from salt anions with internal bonds (sulfates, hydrogen phosphates, etc.) need to be taken into account when employing these spectra for identification purposes. These results also show how Raman spectroscopy can assist the forensic community in drug profiling studies. Furthermore, because their spectra are different, discrimination between the free and protonated forms of amphetamine salts can be observed. Here, we provide evidence for this difference and show experimentally how it has been overseen.

AB - For the first time, the differences between the spectra of amphetamine and amphetamine-H+ and between different conformers are thoroughly studied by ab initio model calculations, and Raman and surface-enhanced Raman spectroscopy (SERS) spectra are measured for different species of amphetamine. The spectra of amphetamine and amphetamine-H+ sampleswere obtained and assigned according to a comparison of the experimental spectra and the ab initio MO calculations, performed using the Gaussian 03W program (Gaussian, Inc., Pittsburgh, PA). The analyses were based on complete geometry minimization of the conformational energy of the S-plus-amphetamine molecule and the S-plus-amphetamine-H+ ion. The harmonic frequency calculations provide information about the characteristic features of the Raman spectra and the nature of the bonding in the molecule. It is concluded that vibrational bands from salt anions with internal bonds (sulfates, hydrogen phosphates, etc.) need to be taken into account when employing these spectra for identification purposes. These results also show how Raman spectroscopy can assist the forensic community in drug profiling studies. Furthermore, because their spectra are different, discrimination between the free and protonated forms of amphetamine salts can be observed. Here, we provide evidence for this difference and show experimentally how it has been overseen.

KW - Ab initio calculation

KW - Raman

KW - Molecular orbital

KW - IR

KW - Amphetamine

KW - Identification

KW - Spectroscopy

KW - Drugs

KW - forensic

KW - SERS

KW - Conformation

U2 - 10.1080/05704928.2010.520180

DO - 10.1080/05704928.2010.520180

JO - Applied Spectroscopy Reviews

JF - Applied Spectroscopy Reviews

SN - 0570-4928

IS - 2

VL - 46

SP - 107

EP - 131

ER -