Fully automated correction for the hematocrit bias of non-volumetric dried blood spot phosphatidylethanol analysis

LC-MS/MS analysis of erythrocyte phosphatidylethanol in haematocrit-corrected whole blood versus isolated erythrocytes: Results of an inter-laboratory comparison

Phosphatidylethanol (PEth) is a non-oxidative metabolite of alcohol (ethanol), which is a sensitive and specific indicator of historic ethanol consumption. Although PEth production from ethanol is catalysed by the ubiquitous enzyme phospholipase D, it resides mainly within the erythrocyte compartment of the blood. PEth analysis has been reported in different preparations of whole blood, representing one of the barriers of inter-laboratory comparisons. We previously reported that expressing PEth concentrations in terms of blood erythrocyte content is more sensitive than whole blood volume, and haematocrit-corrected liquid whole blood calculations of erythrocyte PEth and isolated erythrocyte PEth concentrations are comparable when assayed under identical analytical conditions. Acceptance of a clinical diagnostic assay by accreditation bodies requires proficiency testing with a third-party analytical facility. To explore different blood preparations within the same inter-laboratory program, 60 matched isolated erythrocyte or liquid whole blood specimens were tested at three laboratories. Laboratories measured PEth by liquid chromatography-tandem mass spectrometry (LC-MS/MS), two using isolated erythrocytes, while the third used liquid whole blood, which underwent haematocrit correction before comparison with isolated erythrocyte PEth concentrations. There was acceptable consensus (87%) among laboratories to detect PEth around a cut-off of 35 μg/L of erythrocytes. Each laboratory correlated well with the group average PEth concentration (R > 0.98) for each specimen above the cut-off. Differences were observed between laboratories in bias, which did not affect comparable sensitivity at the selected cut-off. This work demonstrates the feasibility of an inter-laboratory comparison for erythrocyte PEth analysis across different LC-MS/MS methodologies and different blood preparations.

Comprehensive lipidomic profiling by plasma separation cards

Large-scale lipidomic analyses have been limited by the cost and accessibility of traditional venipuncture sampling. Microsampling techniques offer a less-invasive and more accessible alternative. From a single drop of blood, plasma separation cards (PSC) deliver two volumetric dried plasma samples which are studied here for profiling endogenous blood lipids. Six lots of EDTA-treated human whole blood were used to compare PSC, dried blood spot analyses (DBS), and classic wet plasma extractions. Six replicate extractions were performed for each lot. Nontargeted lipidomics was performed by liquid chromatography-high resolution tandem mass spectrometry. Lipids were annotated by accurate mass/retention time matching and MS/MS spectral library matching using peak intensities for quantitation. Four hundred ninety-eight compounds covering 24 lipid subclasses were annotated. Inter-lot repeatability was evaluated by the percent relative standard deviation (%RSD) for each lot, giving median %RSD values across the lots at 14.6% for PSC, 9.3% for DBS, and 8.6% for wet plasma. Strong correlations of lipid peak intensities between wet plasma and PSCs were observed, but less for DBS. Lipid recovery and stability were comparable between the PSC and DBS samples, with roughly 60% of annotated lipids stable at room temperature after 28 days. Overall, PSCs provide a better alternative for quantitative blood lipidomic analyses compared to dried blood spots. However, problems with lipid stability for samples handled and shipped at room temperature are currently unavoidable outside of a clinical setting. Data transferability and comparability to standard plasma is lipid and lipid class dependent.

DropWise: current role and future perspectives of dried blood spots (DBS), blood microsampling, and their analysis in sports drug testing

For decades, blood testing has been an integral part of routine doping controls. The breadth of information contained in blood samples has become considerably more accessible for anti-doping purposes over the last 10 years through technological advancements regarding analytical instrumentation as well as enhanced sample collection systems. Particularly, microsampling of whole blood and serum, for instance as dried blood spots (DBS), has opened new avenues in sports drug testing and substantially increased the availability and cost-effectiveness of doping control specimens. Thus, microvolume blood specimens possess the potential to improve monitoring of blood hormone and drug levels, support evaluation of circulating drug concentrations in competition, and enhance the stability of labile markers and target analytes in blood passport analyses as well as peptide hormone and steroid ester detection. Further, the availability of the fraction of lysed erythrocytes for anti-doping purposes warrants additional investigation, considering the sequestering capability of red blood cells (RBCs) for certain substances, as a complementary approach in support of the clean sport.

In-depth evaluation of automated non-contact reflectance-based hematocrit prediction of dried blood spots

Using the automated CAMAG® DBS-MS 500 HCT system, a UV-Vis-based hematocrit prediction calibration model was succesfully set up and applied on both an independent instrument and an independent set of venous DBS samples.