OBJECTIVE To establish a novel method combining hollow fiber centrifugal ultrafiltration and HPLC for determination of unbound dicloxacillin in human plasma. METHODS Hollow fiber centrifugal ultrafiltration was employed for the pretreatment of plasma samples. The Kromasil C18 column was used for HPLC analysis. The chromatographic conditions were as follows, mobile phase was acetonitrile-25 mmol·L~(-1) phosphate solution(p H 4.5)=40∶60; flow arte was 1.0 m L·min-1; detection wavelength was 225 nm; column tem...