@article{ref1,
title="Challenges for cocaine detection in smuggling samples",
journal="Forensic science international",
year="2020",
author="Eliaerts, J. and Meert, N. and Van Durme, F. and Dardenne, P. and Charles, S. and De Wael, K. and Samyn, N.",
volume="319",
number="",
pages="e110534-e110534",
abstract="Screening of seized cocaine powders is routinely performed by means of colour tests. An alternative fast screening technique is Mid-InfraRed (MIR) spectroscopy. In the  context of smuggling cases, however, drugs are often processed to circumvent  detection. In this study, the current screening techniques (cocaine colour test and  MIR spectroscopy using libraries and chemometrics) were applied to five smuggling  cases. For each case, all samples were first screened with a cocaine colour test and  MIR analysis, followed by confirmation analyses with GC-MS and GC-FID to identify  and quantify cocaine and cutting agents. Finally, Scanning Electron  Microscopy-Energy Dispersive X-ray spectroscopy (SEM-EDX) analyses were performed  for additional characterization. All smuggling samples tested negative, both on-site  as in the laboratory, for cocaine with the cocaine colour test. Four smuggling cases  consisted of coloured samples. Consequently the colour test result was influenced  because discolouration of the test showed almost the same colour as the colour of  the powders (brown, green, red or black). In contrast, the (coloured) powders could  be measured with MIR, but the MIR spectra showed no hit for cocaine using a  reference library search. Moreover, cocaine was not detected in four out of the five  cases after application of a chemometric classification model. GC-MS analysis, the  golden standard for identification, resulted in a positive identification of cocaine  in all cases. These samples contained cocaine ranging between 0.8w% and 35w%. Taking  into account the results of the screening, the chromatographic and the SEM-EDX  analyses, it could be presumed that cocaine was masked. False negative screening  results were caused by chemically modified cocaine and/or cocaine mixed with  coloured powders. In additional experiments, a sample extraction step prior to the  screening techniques was performed. Two sample preparation methods (acetone and  ethyl acetate) were tested and resulted in a positive screening of cocaine with the  colour test and/or MIR spectroscopy. It can be concluded that the outcome of  screening techniques such as colour tests and MIR spectroscopy is only presumptive  and should always be confirmed.<p /> <p>Language: en</p>",
language="en",
issn="0379-0738",
doi="10.1016/j.forsciint.2020.110534",
url="http://dx.doi.org/10.1016/j.forsciint.2020.110534"
}