# An LC/MS/MS method for quantifying 25-hydroxyvitamin D3 in finger-prick plasma sample prepared by DEMECAL® micro plasma separation device: toward mail-in assessment of vitamin D status

## TL;DR

This study presents a new method for measuring vitamin D levels using a finger-prick blood sample, enabling at-home testing and mail-in analysis for better health management.

## Contribution

A novel, non-invasive LC/MS/MS method combined with a self-use blood separation device for mail-in vitamin D status assessment.

## Key findings

- The developed method achieved a lower limit of quantification of 0.10 ng/mL for 25(OH)D3.
- 25(OH)D3 was stable in samples for 7 days at room temperature and 30 days at 4°C.
- The method's results matched those of traditional venipuncture-based procedures.

## Abstract

A mail-in assessment of vitamin D status will make it possible for the subjects to early detect any vitamin D insufficiency/deficiency at their homes, thus leading to a better management of their health. In this study, a liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI–MS/MS) method was developed and validated for quantifying 25-hydroxyvitamin D3 [25(OH)D3], which is the established marker of the vitamin D status, in the finger-prick blood plasma sample prepared by the DEMECAL® device. By using the DEMECAL® device, the subjects can collect their finger-prick blood at their homes and immediately separate the plasma from the blood by themselves. The DEMECAL®-based procedure had advantages over the venipuncture- and dried blood spot-based procedures because it is less invasive and a medical professional-free blood collection, and no need to be concerned with the heterogeneity of the analyte distribution in the sample. The developed LC/ESI–MS/MS method enabled the precise and accurate quantification of 25(OH)D3 and provided the lower limit of quantification of 0.10 ng/mL in the diluted plasma sample due to the derivatization with 4-(4-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione. 25(OH)D3 was stable in the plasma sample prepared by the DEMECAL® device at room temperature (23–27 °C) for 7 days (simulated condition in the mail) and at 4 °C for 30 days (simulated condition during storage at a laboratory). The measured 25(OH)D3 concentrations by the DEMECAL®-based procedure well agreed with those by the conventional venipuncture-based procedure. These results demonstrated that the derivatization-LC/ESI–MS/MS combined with the DEMECAL®-based sample preparation is a promising procedure for the mail-in assessment of the vitamin D status.