New Automated High-performance Liquid-chromatographic Analysis of Cyclosporine-a and Cyclosporine-g in Human-serum

An automated isocratic high-performance liquid chromatographic (HPLC) method is described for the determination of cyclosporin A and G in human serum. This method involves the use of an automated solid-liquid extraction procedure following rapid protein precipitation with acetonitrile. The use of a disposable C8 extraction cartridge allows a good recovery of cyclosporine (87%) from serum and a detection limit of 20 ng/ml with good reproducibility using 0.5 ml of sample. This method can also be adapted to whole blood measurements. The choice of a 3-micron cyano analytical column and of the mobile phase hexane-isopropanol (85:15) permitted a low column temperature (50 degrees C), a low flow-rate (0.6 ml/min) and a short run time (14 min). This method allows the accurate and fast routine monitoring of cyclosporine by HPLC, which is particularly important in hepatic transplantations.