Quantitation of phosphatidylethanol in dried blood after volumetric absorptive microsampling

Background: Stimulated by the increased recognition of phosphatidylethanol (PEth) as sensitive direct marker of alcohol intake, the Ghent University's Laboratory of Toxicology and the National Institute of Criminalistics and Criminology combined their efforts to develop a quantitative method. To facilitate implementation the focus was on the use of a sampling technique which allows quick and easy blood collection, without the need of dedicated personnel at any place/any time. In the meantime the cooperation of the two labs should also allow to initiate a Belgian network of laboratories capable of quantifying PEth. Methods: Dried blood microsamples were collected via volumetric absorptive microsampling (VAMS). PEth 16:0/ 18:1 was quantified after liquid-liquid extraction using two independent isotope dilution - liquid chromatography - tandem mass spectrometry methods. A systematic review of the entire process at both sites was performed before the final method comparison using samples from 59 routine toxicology cases collected within a one-year time interval. Results: Initial differences between both laboratories were solved by focusing on important methodological aspects: (i) trueness verification of the calibration protocol focusing on the primary material, preparation of the stock solutions and adequate equilibration of calibrators and QCs, and (ii) verification of comparability of results obtained with different m/z transitions. Several of these aspects could only be verified by critically assessing spiked and native samples. After a final validation good average comparability of the two methods was observed. The average bias was -0.4%, with 85% of the differences within 20%. Moreover, the methods proved to be reproducible and robust within a one-year time interval. Conclusion: This study is the first to develop a quantitative volumetric absorptive microsampling based method for PEth measurements, in addition it is the first to perform a systematic comparison of PEth measurements between two laboratories. From the discussion on the encountered pitfalls it is clear that also on a global scale, more efforts are needed to improve interlaboratory agreement

Preanalytical, Analytical, and Computational Factors Affect Homeostasis Model Assessment Estimates

OBJECTIVE—We investigated how β-cell function and insulin sensitivity or resistance are affected by the type of blood sample collected or choice of insulin assay and homeostatis model assessment (HOMA) calculator (http://www.dtu.ox.ac.uk)

Cov2MS: an automated and quantitative matrix-independent assay for mass spectrometric measurement of SARS-CoV-2 nucleocapsid protein

Analytical BioScience

A statistical basis for harmonization of thyroid stimulating hormone immunoassays using a robust factor analysis model

Background: Between-method equivalence ideally is achieved by calibration against an SI-traceable reference measurement procedure. For measurement of thyroid stimulating hormone (TSH), it is unlikely to accomplish this goal in mid-term. Therefore, we investigated a statistical alternative based on a factor analysis (FA) model. Methods: The FA model was applied to TSH results for 94 samples generated by 14 immunoassays (concentration range: 0.0005–78 mIU/L). The dataset did not fulfill the assumption of a homogeneous sample from an elliptically symmetric distribution, and, therefore, required standardization prior to application of the FA model. As outliers and missing values also occurred, the key quantities of the FA model had to be estimated with a method that can handle these complications. We selected a robust alternating regressions (RAR) method, which replaces in the minimization criterion of the fitting process the squared differences between results xij and model fit ˆij x by a weighted absolute difference. The weights are adaptively determined in successive regressions, which down weighs the outliers. The weights for missing values are set to zero. Results: The quality of the estimated targets was reflected by their central position in the distributions, and description of the relationship between results and targets by a simple two-parameter regression equation with high correlation coefficients and low SDs of the percentage-residuals. Mathematical recalibration eliminated the method differences and improved the between-method CV from 11% to 6%. Conclusions: RAR applied to a multimethod comparison dataset hampered by outliers and missing values, is fit to the purpose of harmonization.status: publishe

Harmonization of immunoassays to the all-procedure trimmed mean - proof of concept by use of data from the insulin standardization project

status: publishe

Current evolutions, applications, and challenges of phosphatidylethanol analysis for clinical and forensic purposes

Phosphatidylethanols (PEth) are a group of abnormal phospholipids which are formed within the human body in the presence of ethanol. As PEth accumulates in red blood cells, which prolongs its detectability, it became popular as a direct alcohol biomarker. When alcohol is consumed regularly, PEth concentrations in the human blood reach an equilibrium (plateau) between formation and degradation which is representative of drinking habits. A wide range of applications has been demonstrated for PEth, whereby in most studies it could provide advancements regarding accuracy and precision when compared to already established alcohol biomarkers (carbohydrate-deficient transferrin, gamma-glutamyltransferase, and ethyl glucuronide). Although PEth has been the focus of many research projects all around the world, the final breakthrough from the research laboratory into the clinical mass market is still ongoing. In this overview article, we discuss the evolution of PEth analysis, its applications, and the associated challenges. The main reasons that hinder the use of PEth in the mass market were identified as (a) the lack of implementing a uniform reference measurement system, which should ensure that every single PEth result is comparable and/or (b) ensuring good laboratory practice dedicated to PEth analysis, which should guarantee that every result obtained by an individual laboratory is correct. These challenges regarding PEth analytics must be carefully addressed in the near future before the implementation of common cut-off values and international guidelines can take place

Cannabinoid receptor activation potential of the next generation, generic ban evading OXIZID synthetic cannabinoid receptor agonists

In recent years, several nations have implemented various measures to control the surge of new synthetic cannabinoid receptor agonists (SCRAs) entering the recreational drug market. In July 2021, China put into effect a new generic legislation, banning SCRAs containing one of seven general core scaffolds. However, this has driven manufacturers towards the synthesis of SCRAs with alternative core structures, exemplified by the recent emergence of "OXIZID SCRAs." Here, using in vitro beta-arrestin2 recruitment assays, we report on the CB1 and CB2 potency and efficacy of five members of this new class of SCRAs: BZO-HEXOXIZID, BZO-POXIZID, 5-fluoro BZO-POXIZID, BZO-4en-POXIZID, and BZO-CHMOXIZID. All compounds behaved as full agonists at CB1 and partial agonists at CB2. Potencies ranged from 84.6 to 721 nM at CB1 and 2.21 to 25.9 nM at CB2. Shortening the n-hexyl tail to a pentyl tail enhanced activity at both receptors. Fluorination of this pentyl analog did not yield a higher receptor activation potential, whereas an unsaturated tail resulted in decreased potency and efficacy at CB1. The cyclohexyl methyl analog BZO-CHMOXIZID was the most potent compound at both receptors, with EC50 values of 84.6 and 2.21 nM at CB1 and CB2, respectively. Evaluation of the activity of a seized powder containing BZO-4en-POXIZID suggested a high purity, in line with high-performance liquid chromatography coupled to diode-array detection (HPLC-DAD), gas chromatography coupled to mass spectrometry (GC-MS), liquid chromatography coupled to time-of-flight mass spectrometry (LC-QTOF-MS), and Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analysis. Furthermore, all tested compounds showed a preference for CB2, except for BZO-POXIZID. Overall, these findings inform public health officials, law enforcement agencies, and clinicians on these newly emerging SCRAs

A new cannabinoid receptor 1 selective agonist evading the 2021 'China ban': ADB‐FUBIATA

Following the class-wide ban of synthetic cannabinoid receptor agonists (SCRAs) in China, SCRAs carrying new core and linker structures, aimed at circumventing the recent Chinese generic legislation, have appeared on the recreational drug market. A very recent example is (S)-2-(2-(1-(4-fluorobenzyl)-1H-indol-3-yl)acetamido)-3,3-dimethylbutanamide (ADB-FUBIATA), which is structurally closely related to the potent SCRA ADB-FUBICA, but carries an additional methylene in the linker region of the molecule. ADB-FUBIATA has recently been identified in seized materials in China, Russia, the United States, and also Belgium; however, its pharmacological characteristics were unknown. The aim of this study was to evaluate the intrinsic cannabinoid receptor (hCB(1) and hCB(2)) activation potential of this previously unknown substance via two distinct yet similar in vitro beta-arrestin2 recruitment assays, based on the NanoLuc Binary Technology (R). At CB1, a potency of 635 nM (EC50) was found, with an efficacy (E-max) of 141% relative to the reference compound CP55,940. On the other hand, ADB-FUBIATA had almost no activity at CB2, indicative of a clear CB1 selectivity. Interestingly, this activation pattern differs markedly from that observed for ADB-FUBICA, which was previously found to be potent and efficacious at both cannabinoid receptors. Additionally, the bioassays were applied to a seized powder containing ADB-FUBIATA, as analytically confirmed by high-performance liquid chromatography coupled to diode-array detection (HLPC-DAD), gas chromatography coupled to mass spectrometry (GC-MS), liquid chromatography couple to time-of-flight mass spectrometry (LC-QTOF-MS), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The EC50 and E-max values obtained for this powder were very similar to those of the ADB-FUBIATA analytical standard, suggesting a high purity of the powder, although analytical techniques did reveal that the sample was not entirely pure