DETERMINATION OF TACROLIMUS (FK-506) IN WHOLE-BLOOD USING LIQUID-CHROMATOGRAPHY AND FLUORESCENCE DETECTION

A sensitive and selective liquid chromatographic method, using precolu mn derivatization with dansylhydrazine followed by fluorescence detect ion, has been developed for the determination of tacrolimus (FK 506) i n whole blood. After haemolysis, whole blood samples are extracted wit h diethyl ether and derivatized. After on-line removal of excess dansy lhydrazine on a C-18 precolumn, the derivative is loaded on to a C-18 clean-up column, and a heart cut is subsequently transferred to a grap hitized carbon column, where the final separation takes place. The met hod requires 1 ml of sample and has a limit of quantitation of 3 ng/ml . At the 15 ng/ml level the precision is ca 10 %, and the response is linear from the limit of quantitation to ca 200 ng/ml of FK 506 in who le blood. The capacity of the method is 50 samples/day and about 1000 1-ml samples can be analyzed without changing either clean-up or separ ation column. Finally, the applicability of the method for therapeutic drug monitoring is shown.