Correlation of Cocaine Hydrochloride Samples Seized in Brazil Based on Determination of Residual Solvents: An Innovative Chemometric Method for Determination of Linkage Thresholds

Abstract

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.

Determination of cocaine and its main adulterants in seized drugs from Rio Grande do Sul, Brazil, by a Doehlert optimized LC-DAD method

“…The adulteration pattern changed according to region. Moreover, Zacca et al 11 evaluated a statistical method to link seizures through the cocaine's residual solvent prole to identify the trafficking networks. Caffeine, diltiazem and hydroxyzine were also found, but less oen.…”

Profiling of synthesis‐related impurities of the synthetic cannabinoid Cumyl‐5F‐PINACA in seized samples of e‐liquids via multivariate analysis of UHPLC−MSn data

“…Several methodologies of the analysis of organic impurities or by‐products were developed for classic drugs like cocaine, heroin, and amphetamine . They mostly consisted of a straightforward liquid–liquid extraction (LLE) or solid‐phase extraction (SPE) procedure to remove the main active substance and to enrich related by‐products, followed by analysis via gas chromatography (GC) or liquid chromatography (LC) coupled to different types of detectors . The chromatographic signatures were then quantitatively evaluated via database‐assisted chemometric models.…”

Chemical profiling of the synthetic cannabinoid MDMB‐CHMICA: Identification, assessment, and stability study of synthesis‐related impurities in seized and synthesized samples

“…In the first step of common impurity‐profiling workflows, the seized material is dissolved and impurities are separated from the main component by acid–base liquid–liquid extraction (LLE), followed by analysis of the enriched impurity extract via liquid or gas chromatography coupled to mass spectrometry (LC–MS or GC–MS) . The integrated peak signals of a list of pre‐defined key‐impurities are then matched via chemometric models to databases of previously seized samples .…”

“…8 In the first step of common impurity-profiling workflows, the seized material is dissolved and impurities are separated from the main component by acid-base liquid-liquid extraction (LLE), followed by analysis of the enriched impurity extract via liquid or gas chromatography coupled to mass spectrometry (LC-MS or GC-MS). [9][10][11][12] The integrated peak signals of a list of pre-defined key-impurities are then matched via chemometric models to databases of previously seized samples. 2,3,13,14 The decision whether two samples are somehow linked (eg, come from the same synthesis, the same laboratory, or the same synthesis route) or are not related to each other, requires a thoroughly assessed scientific basis, especially with respect to the legal defensibility of the profiling results.…”