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Rapid classification and quantification of cocaine in seized powders with ATR-FTIR and chemometrics.

Authors
  • Eliaerts, Joy1, 2
  • Dardenne, Pierre3
  • Meert, Natalie1
  • Van Durme, Filip1
  • Samyn, Nele1
  • Janssens, Koen2
  • De Wael, Karolien2
  • 1 Department of Toxicology and Drugs, National Institute of Criminalistics and Criminology, Brussels, Belgium. , (Belgium)
  • 2 AXES Research Group, Chemistry Department, University of Antwerp, Antwerp, Belgium. , (Belgium)
  • 3 Walloon Agricultural Research Centre, Gembloux, Belgium. , (Belgium)
Type
Published Article
Journal
Drug Testing and Analysis
Publisher
Wiley (John Wiley & Sons)
Publication Date
Oct 01, 2017
Volume
9
Issue
10
Pages
1480–1489
Identifiers
DOI: 10.1002/dta.2149
PMID: 27977911
Source
Medline
Keywords
License
Unknown

Abstract

Traditionally, fast screening for the presence of cocaine in unknown powders is performed by means of colour tests. The major drawbacks of these tests are subjective colour evaluation depending on the operator ('50 shades of blue') and a lack of selectivity. An alternative fast screening technique is Fourier Transform InfraRed (FTIR) spectrometry. This technique provides spectra that are difficult to interpret without specialized expertise and shows a lack of sensitivity for the detection of cocaine in mixtures. To overcome these limitations, a portable FTIR spectrometer using Attenuated Total Reflectance (ATR) sampling was combined with a multivariate technique, called Support Vector Machines (SVM). Representative street drug powders (n = 482), seized during the period January 2013 to July 2015, and reference powders (n = 33) were used to build and validate a classification model (n = 515) and a quantification model (n = 378). Both models were compared with the conventional chromatographic techniques. The SVM classification model showed a high sensitivity, specificity, and efficiency (99%). The SVM quantification model determined cocaine content with a root mean squared error of prediction (RMSEP) of 6% calculated over a wide working range from 4 to 99 w%. In conclusion, the developed models resulted in a clear output (cocaine detected or cocaine not detected) and a reliable estimation of the cocaine content in a wide variety of mixtures. The ATR-FTIR technique combined with SVM is a straightforward, user-friendly, and fast approach for routine classification and quantification of cocaine in seized powders. Copyright © 2016 John Wiley & Sons, Ltd.

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