LC/MS Analysis of 25-Hydroxyvitam D₃ and 25-Hydroxyvitamin D₂ on Ascentis^® Express C18

column

Ascentis Express C18, 5 cm x 2.1 mm I.D., 2.7 μm particles (53822-U)

mobile phase

[A] 10mM ammonium formate in water; [B] 10mM ammonium formate in acetonitrile; (32:68, A:B)

flow rate

0.4 mL/min

pressure

1711 psi (118 bar)

column temp.

35 °C

detector

ESI(+)

injection

2 μL

sample

10 μg/mL in 25:75, water:methanol