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Spectroscopy
Volume 24, Issue 6, Pages 601-608
http://dx.doi.org/10.3233/SPE-2010-0482

Fourier transform infrared and near-infrared spectroscopic methods for the detection of toxic Diethylene Glycol (DEG) contaminant in glycerin based cough syrup

M. Khalique Ahmed,1,4 Michael P. McLeod,2 Jean Nézivar,1 and Allison W. Giuliani3

1Department of Science, College of Liberal Education, Lynn University, North Military Trail, Boca Raton, FL, USA
2University of Miami, Miller School of Medicine at Florida Atlantic University, Boca Raton, FL, USA
3Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL, USA
4Department of Science, College of Liberal Education, Lynn University, 3601 North Military Trail, Boca Raton, FL 33431, USA

Copyright © 2010 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Recently there have been reports of the contamination of cough syrups with Diethylene Glycol (DEG). The consumption of such cough syrups has devastating effects on the health. In this paper we report evidence that Fourier transform infrared (FT-IR) and near-infrared (NIR) spectroscopic techniques are viable, simple, cost effective, rapid and fool proof methods for the identification and quantification of DEG in glycerin based cough syrups. The FT-IR and NIR spectra of the glycerin based cough syrup and up to 50:50 mixtures of DEG in cough syrup are recorded. The major peaks in the FT-IR spectrum of the cough syrup are assigned to the OH stretching (∼3300 cm−1), CH stretching (∼2900 cm−1), CH bending (1500–1200 cm−1) and C–O stretching (1200–900 cm−1) vibrational modes. In the FT-IR spectra of the mixtures, DEG contribute distinct peaks due to the vibrations of the C–O (920 cm−1) and OC2H4 (892 cm−1) moieties of its backbone and form the basis of the DEG detection and quantification. The prominent peaks of the NIR spectra of cough syrup and DEG are assigned to the first overtones of OH and CH, and to the combination of OH and CH fundamental vibrations. Both FT-IR and NIR Partial Least Square (PLS) calibrations produced correlation coefficients of 0.98.