Laurence Dujourdy

A methodology for illicit heroin seizures comparison in a drug intelligence perspective using large databases

To characterise links between different illicit drugs chemical profiles, various distance or correlation measurements are available.Different comparison methods have been tested and a method based on a correlation coefficient using a square cosine function was chosen to compare heroin chemical profiles. Its functioning and graphical representation are described. An assessment of the number of false positives is calculated and lead to a negligible number.Moreover, it emerges from the studies that possible variations in impurity peak areas subject to possible degradations do not influence the C correlation value nor question the already established links. This solid, reliable and simple method appears therefore suitable for heroin samples comparison, links profiling and routine use.

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

Harmonisation and optimization of analytical and statistical methodologies were carried out between two forensic laboratories (Lausanne, Switzerland and Lyon, France) in order to provide drug intelligence for cross-border cocaine seizures. Part I dealt with the optimization of the analytical method and its robustness. This second part investigates statistical methodologies that will provide reliable comparison of cocaine seizures analysed on two different gas chromatographs interfaced with a flame ionisation detectors (GC-FIDs) in two distinct laboratories. Sixty-six statistical combinations (ten data pre-treatments followed by six different distance measurements and correlation coefficients) were applied. One pre-treatment (N+S: area of each peak is divided by its standard deviation calculated from the whole data set) followed by the Cosine or Pearson correlation coefficients were found to be the best statistical compromise for optimal discrimination of linked and non-linked samples. The centralisation of the analyses in one single laboratory is not a required condition anymore to compare samples seized in different countries. This allows collaboration, but also, jurisdictional control over data.

A study of cannabis potency in France over a 25 years period (1992–2016)

Cannabis contains a unique class of compounds known as the cannabinoids. Pharmacologically, the principal psychoactive constituent is Δ9-tetrahydrocannabinol (THC). The amount of THC in conjunction with selected additional cannabinoid compounds (cannabidiol/CBD, cannabinol/CBN), determines the strength or potency of the cannabis product. Recently, reports have speculated over the change in the quality of cannabis products, from nearly a decade, specifically concerning the increase in cannabinoid content. This article exploits the analytical data of cannabis samples analyzed in the five French forensic police laboratories over 25 years. The increase potency of both herbal and resin cannabis in France is proved through the monitoring of THC content. For cannabis resin, it has slowly risen from 1992 to 2009, before a considerable increase in the last four years (mean THC content in mid-2016 is 23% compared to 10% in 2009). For herbal cannabis, it has known three main stages of growth (mean THC content is 13% in 2015 and mid-2016 compared to 7% in 2009 and 2% in 1995). The calculation of THC/CBD ratios in both herbal and resin samples confirms the recent change in chemotypes in favor of high potency categories. Finally, the CBN/THC ratios in marijuana samples were measured in order to evaluate the freshness of French seized hemp.

Multidimensional analysis of cannabis volatile constituents: identification of 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane as a volatile marker of hashish, the resin of Cannabis sativa L.

The volatile constituents of drug samples derived from Cannabis sativa L. were investigated by means of headspace solid phase microextraction (HS-SPME) and gas chromatography techniques (GC-MS, GC×GC-MS). Samples of cannabis herb and hashish showed clear differences in their volatile chemical profiles, mostly resulting from photo-oxidation processes occurring during the transformation of fresh cannabis herb into hashish. Most unexpectedly, we could demonstrate hashish samples as containing remarkable amounts of a rare and unusual monoterpene - 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane - among the volatile compounds detected in their headspaces. We gave evidence for the formation of this compound from the light induced rearrangement of β-myrcene during the manufacture of hashish. In view of its high abundance among volatile constituents of cannabis resin and its scarce occurrence in other natural volatile extracts, we propose to rename this specific monoterpene hashishene.

IRMS to study a common cocaine cutting agent: phenacetin.

Phenacetin is a pharmaceutical closely related to acetaminophen that has been banned in France for a long time due to its nephritic and carcinogenic adverse effects. It frequently appears in cocaine seizures as a cutting agent. Following both sanitary and intelligence motivations, this molecule was chosen for this study, and stable isotopes seemed to be the most appropriate tool. A total of 228 seized samples were collected over a 6-year period, and 8 standards of known origin were purchased. They were submitted to gas chromatography (GC) or elemental analysis - isotope ratio mass spectrometry (EA-IRMS) measurements, depending on their complexity. Stable isotope ratios of carbon, hydrogen, and nitrogen for a part of the sample set, were acquired. The isotopic values of phenacetin standards acquired from various providers located worldwide are quite spread, which indicates that stable isotopes could be used to discriminate manufacturers. However, the measured values of most of the seized samples are concentrated in a narrow range, tending to demonstrate that phenacetin is smuggled from a single source or similar ones. Consequently, stable isotopes could only be used to exclude that several samples come from a common source. Copyright

À la recherche du juste dosage : statistique appliquée à l’analyse de la cocaïne

A method of separation by gas chromatography with a flame ionization detector was developed for quantifying cocaine in powders seized by the police. The method was validated by studying parameters of calibration, trueness, precision based on trueness error (or systematic bias) and random error. Total error, which is the combination of these errors, is used to confirm the method adequacy with the objectives fixed by the analyst. Accuracy profile is an efficient decision tool to do it. Results obtained with weighted regression model allow concluding that the method fits quantitation of heroin and cocaine in powders on 2 to 100% concentration (w/w) domain with 10% limits of acceptation and a risk of 5%.

What a validation strategy means for the quantitation of cocaine and heroin

A method of separation by gas chromatography with a flame ionisation detector was developed for quantifying cocaine and heroin in powders seized by law enforcement. The method was validated by studying parameters of calibration, trueness, precision based on trueness error (or systematic bias) and random error. Total error, which is the combination of these errors, verified its adequacy with the objectives fixed by the analyst. Accuracy profile proved to be an efficient decision tool for that purpose. Results obtained with weighted regression model were analysed and allowed to conclude that the method enables quantitation of heroin and cocaine in powders on 2-100% concentration (w/w) range with acceptance limits fixed at 10% and a risk at 5%. The possible sources of uncertainty were evaluated and measurement of their contribution was integrated. The combined standard uncertainty and expanded uncertainty were determined.