Candidate reference method for determination of vitamin D from dried blood spot samples.

A new interesting article has been published in Clin Chem Lab Med. 2019 Jul 25. pii: /j/cclm.ahead-of-print/cclm-2019-0397/cclm-2019-0397.xml. doi: 10.1515/cclm-2019-0397. and titled:

Candidate reference method for determination of vitamin D from dried blood spot samples.

Authors of this article are:

Zakaria R, Allen KJ, Koplin JJ, Roche P, Greaves RF.

A summary of the article is shown below:

Background The current millennium has seen an explosion in vitamin D testing with the overarching aim of requests to clinically stratify patients as replete or deficient in vitamin D. At a population level, dried blood spot (DBS) sampling offers a less invasive and more practical application for assessment of vitamin D status. We have therefore aimed to develop a sensitive and robust DBS vitamin D method that is traceable to serum for use in population-based studies. Methods Blood spots, calibrators and controls were prepared by punching a 3.2 mm DBS from filter paper and placed into a 96-well micro-plate. The DBS disk was eluted with a combination of water-methanol and internal standard (ISTD) solution followed by supported-liquid extraction and derivatisation. The extract was analysed by liquid-chromatography tandem-mass spectrometry in positive electrospray-ionisation mode with 732.5 > 673.4 and 738.4 > 679.4 m/z ion-transitions for derivatised vitamin D and the ISTD, respectively. Vitamin D results were made traceable to the National Institute of Standards and Technology reference material through the inclusion of Chromsystems vitamin D calibrators. Results 25-Hydroxy-vitamin D3 and its related ISTD were detected at a retention time of 7 min. The seven-point calibration-curve consistently demonstrated a coefficient of determination of 0.99 with an experimentally determined reportable range of 0.5-376 nmol/L. Method validation studies using DBS samples demonstrated 12.9% between-assay imprecision at 45 nmol/L, 84% average recovery and high correlation with plasma vitamin D (correlation coefficient = 0.86). Conclusions We have successfully developed an analytical method for vitamin D quantitation from DBSs which will be applied to our population-based vitamin D research study. This approach improves traceability of DBS results and potentially could be used broadly for other DBS measurands that require comparison to serum/plasma for their interpretation.

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This article is a good source of information and a good way to become familiar with topics such as: dried blood spot;liquid chromatography;tandem mass spectrometry;vitamin D.

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