Correlation of cocaine hydrochloride samples seized in Brazil based on determination of residual solvents: an innovative chemometric method for determination of linkage thresholds.

Cocaine sample correlation provides important information in the identification of traffic networks. However, available methods for estimating if samples are linked or not require the use of previous police investigation and forensic expert knowledge regarding the number of classes and provide thresholds that are both static and data set specific. In this paper, a novel unsupervised linkage threshold method (ULT) based on chemometric analysis is described and applied to the analysis of headspace gas chromatography mass spectrometry (HS-GC/MS) data of more than 250 real cocaine hydrochloride samples seized by Brazilian Federal Police. The method is capable of establishing linkage thresholds that do not require any prior information about the number of classes or distribution of the samples and can be dynamically updated as the data set changes. It is envisaged that the ULT method may also be applied to other forensic expertise areas where limited population knowledge is available and data sets are continually modified with the inflow of new information.

[1]  M. Chiarotti,et al.  ANALYSIS OF VOLATILE COMPOUNDS IN HEROIN SAMPLES , 1988 .

[2]  F Taroni,et al.  A methodology for illicit heroin seizures comparison in a drug intelligence perspective using large databases. , 2003, Forensic science international.

[3]  S Lociciro,et al.  Cocaine profiling for strategic intelligence, a cross-border project between France and Switzerland: part II. Validation of the statistical methodology for the profiling of cocaine. , 2008, Forensic Science International.

[4]  G. Carrera,et al.  Static headspace gas chromatographic method for quantitative determination of residual solvents in pharmaceutical drug substances according to european pharmacopoeia requirements. , 2004, Journal of chromatography. A.

[5]  Pierre Esseiva,et al.  Illicit drug profiling, reflection on statistical comparisons. , 2011, Forensic science international.

[6]  Laurence Dujourdy,et al.  A quick and automated method for profiling heroin samples for tactical intelligence purposes. , 2007, Forensic science international.

[7]  Philip Doble,et al.  Chemical profiling and classification of illicit heroin by principal component analysis, calculation of inter sample correlation and artificial neural networks. , 2005, Talanta.

[8]  A. Moreda-Piñeiro,et al.  Gas chromatographic-mass spectrometric analysis of residual solvent trapped into illicit cocaine exhibits using head-space solid-phase microextraction. , 2002, Journal of chromatography. B, Analytical technologies in the biomedical and life sciences.

[9]  M D Cole.  Occluded Solvent Analysis as a Basis for Heroin and Cocaine Sample Differentiation. , 1998, Forensic science review.

[10]  David R Morello,et al.  Qualitative and Quantitative Determination of Residual Solvents in Illicit Cocaine HCl and Heroin HCl , 1995 .

[11]  Laurence Dujourdy,et al.  Headspace profiling of cocaine samples for intelligence purposes. , 2008, Forensic science international.

[12]  L Dujourdy,et al.  Drug intelligence based on organic impurities in illicit MA samples. , 2008, Forensic science international.

[13]  James R. Ehleringer,et al.  Tracing the geographical origin of cocaine , 2000, Nature.

[14]  F Taroni,et al.  Evaluation of links in heroin seizures. , 2003, Forensic science international.