LC/MS Analysis of Isoflavones on Chromolith^® FastGradient RP-18 endcapped

column

Chromolith FastGradient RP-18, 5 cm x 2.0 mm I.D., 2 μm particles (1.52007.0001)

mobile phase

[A] 0.1% formic acid in water; [B] 0.1% formic acid in acetonitrile

gradient

5 to 15% B in 1.5 min, to 95% B in 4 min, held at 95% B for 1 min, to 5% B in 1 min, held at 5% for 1.5 min

flow rate

0.5 mL/min

pressure

821-317 psi (57 - 22 bar)

column temp.

25 °C

detector

ESI-MS(+) (m/z range 100-600), overlay of four EICs (m/z 271.0, 255.0, 447.1, 417.1)

injection

1 μL

sample

genistein 10 ppb, daidzein 10 ppb, glycitin 10 ppb, puerarin 20 ppb in methanol and water (50:50 v/v)