High-performance liquid chromatography of bile acids with a reversed-phase radial compression column

A reversed-phase radial compression column (Waters Assoc. Radial-Pak C18, 10 micrometers, 8 mm I.D.) has been evaluated for the separation of bile acid standards by high-performance liquid chromatography. With a mobile phase of methanol-water (75:25, v/v) containing 2.5% (v/v) acetic acid and adjusted to pH 5.25 with 10 M sodium hydroxide, a mixture of fifteen bile acids could be resolved, and the ten major conjugated bile acids of human bile were well separated in under 20 min at a flow-rate of 2.0 ml min-1. More rapid separations could be achieved at higher flow-rates. Refractive index detection permitted quantitation of 5 nmoles or less.