Heroin samples [76 South East Asian (SEA), 20 non-South East Asian (non-SEA) and 92 of uncertain origin] were analysed by inductively coupled plasma mass spectrometry for 73 elements. Hierarchical cluster analysis (HCA) grouped together the SEA and many of the non-SEA subgroups, and grouped together elements with similar chemical properties. K-means cluster, correlation and principal component analyses supported the HCA. Logistic models were created using continuous, discrete and a combination of continuous and discrete elemental data in order to predict the SEA or non-SEA origin of samples. The predictive values of the models were 68-100%, the most successful models simultaneously using both continuous and discrete concentration data.

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An interlaboratory comparison (ILC) was conducted to evaluate the proficiency of multiple laboratories to quantify dimethylsulfide (DMS) in aqueous solution. Ten participating laboratories were each supplied with blind duplicate test solutions containing dimethylsulfoniopropionate hydrochloride (DMSP HCl) dissolved in acidified artificial seawater. The test solutions were prepared by the coordinating laboratory from a DMSP HCl reference material that was synthesized and purity certified for this purpose. A concentration range was specified for the test solutions and the participating laboratories were requested to dilute them as required for their analytical procedure, together with the addition of excess alkali under gas-tight conditions to convert the DMSP to DMS. Twenty-two DMS concentrations and their estimated expanded measurement uncertainties (95% confidence level) were received from the laboratories. With two exceptions, the within-laboratory variability was 5% or less and the between-laboratory variability was ~ 25%. The magnitude of expanded measurement uncertainties reported from all participants ranged from 1% to 33% relative to the result. The information gained from this pilot ILC indicated the need for further test sample distribution studies of this type so that participating laboratories can identify systematic errors in their analysis procedures and realistically evaluate their measurement uncertainty. The outcome of ILC studies provides insights into the comparability of data in the global surface seawater DMS database.

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Rationale Two new certified reference materials (CRMs) have been prepared providing three steroids certified for stable carbon isotope delta values, δ(13C) ‰. These materials have been designed to assist anti‐doping laboratories in validating their calibration method or to be employed as calibrant for stable carbon isotope measurements of Boldenone, Boldenone Metabolite 1 and Formestane. These CRMs will allow for accurate and traceable analysis in compliance with World Anti‐Doping Agency (WADA) Technical Document TD2021IRMS. Methods Certification was performed using an elemental analyser‐isotope ratio mass spectrometry (EA‐IRMS) primary reference method on the bulk carbon isotope ratios of nominally pure steroid starting materials. EA‐IRMS analyses were carried out on a Flash EA Isolink CN coupled via a Conflo IV to a Delta V plus mass spectrometer. Confirmation analysis was performed by gas chromatography‐combustion‐isotope ratio mass spectrometry (GC‐C‐IRMS) using a Trace 1310 GC coupled to a Delta V plus mass spectrometer via GC Isolink II. Results Based on the EA‐IRMS analysis, the materials were certified with δ(13C) values of −30.38‰ (Boldenone), −29.71‰ (Boldenone Metabolite 1) and 30.71‰ (Formestane). Noting that the assumption of 100% purity in the starting materials has the potential to introduce bias, this was investigated using GC‐C‐IRMS analysis and theoretical modelling based on purity assessment data. Conclusions Careful application of this theoretical model was shown to provide reasonable estimates of uncertainty while avoiding the introduction of errors associated with analyte‐specific fractionation during GC‐C‐IRMS analysis.