Abstract:

Objective To establish a method for determining the concentrations of 25-hydroxyvitamin D2[25(OH)D2] and 25-hydroxyvitamin D3[25(OH)D3] in cord blood. Methods The serum samples from cord blood were pretreated by acetonitrile and ZnSO₄.High performance liquid chromatography tandem-mass spectrometry (LC-MS/MS) was used for the determinations of 25(OH)D2 and 25(OH)D3 concentrations. The analysis was carried on a Poroshell^? 120 EC-C18 column. Electrospray ionization(ESI), multiple reaction monitor (MRM), nebulizer 35.0 psi, gas temperature 180℃, sheath gas temperature 350℃ and sheath gas flow 11.0 L/min were performed. The column temperature was 50℃ with linear gradient elution using methanol(80%)and water(20%), and the flow rate was 0.5 mL/min. The quantitative analysis was performed by selective reaction monitoring mode of heater ESI. Results A good linearity was detected in the linear range of 3.125-100 ᠜g/L for 25(OH) D2 and 25(OH) D3 (R²=0.998 7 and 0.999 1). Blood samples had frozen and thawed for 3 times. Both intra-day and inter-day relative standard deviations (RSD) were <15%. The quality control materials of serum 25(OH)D2 and 25(OH)D3 were analyzed, and the results met the requirements of quality control. Conclusions LC-MS/MS is sensitive, rapid and suitable for the determinations of serum 25(OH)D2 and 25(OH)D3 concentrations in cord blood.

Key words: 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, Liquid chromatography tandem-mass spectrometry, Cord blood