Liquid chromatographic assay of ketoconazole

A reverse-phase, high-pressure liquid chromatographic method for the rapid and quantitative determination of ketoconazole has been developed. Drug levels from 0.5 to 10 microgram/ml can be determined in either yeast nitrogen base medium or human serum by using an octadecylsilane column. A retention time of 4.9 +/- 0.1 min resulted when the drug was eluted from a column with 75% methanol-25% 0.02 M (pH 7.5) phosphate buffer at a flow rate of 2 ml/min. Optimum sensitivity was obtained at a wavelength of 231 nm.