Determination of fluconazole by direct injection of plasma and high performance liquid chromatography with column switching.

High performance liquid chromatography with column switching has been developed for the determination of fluconazole in plasma. The plasma samples were injected onto a precolumn packed with LiChromprep RP2(25-40 microns) after simple dilution with a solution of 0.2 mol.L-1 acetic acid. Distilled water was used to wash out protein and other polar components in plasma. After switching, the concentrated fluconazole was eluted in the back-flush mode onto a Shimpack CLC-ODS column with methanol--0.2 mol.L-1 ammonium acetate (pH 2.7) (50:50) as mobile phase. Purge solutions were used for clean-up and for regenerating the precolumn. The method showed a good precision and excellent recovery. The detection limit was 0.12 micrograms.ml-1 plasma. The RSD's (intra- and interday) were less than 6.3%. The method has been successfully used to determine bioavailability and pharmacokinetics of fluconazole in Chinese volunteers.