A Direct LC/MS/MS Method for Quantitative Determination of 25-Hydroxyvitamin D2 and D3 in Human Plasma

Introduction

Vitamin-D is an essential nutrient for human health. Vitamin-D deficiency has been reported among populations, which is potentially a factor to develop chronic diseases. The level of vitamin-D is maintained by its metabolite 25OH-vitamin-D2/D3 in the bloodstream. Vitamin-D dereciency is normally defined as its serum level below 50~75nmol/mL. Therefore, accurate measurement of vitamin D status is required in clinical screening test. In recent year, LC/MS/MS has been used for quantitative analysis of vitamin-D metabolites. However, tedious sample preparation is often required such as extraction, derivatization and clean-up with SPE or immunoaffinity columns. This is to remove matrix interferences and increase sensitivity due to poor ionization of the compounds [1, 3]. Furthermore, the amount of serum/plasma required was rather high at 0.5~2 mL per analysis, which is not favourable in the clinical applications. Here, we present a direct high sensitivity LC/MS/MS method for quantitative determination of 25OH-vitamin-D2/D3 in plasma, achieving LLOQ of 3ng/mL with 10uL injection. The method exhibits good accuracy, reproducibility, linearity and specificity over the concentration range from 1-100 ng/mL.

May 26, 2015 GMT