Liquid chromatographic determination of cyclosporine in whole blood with the advanced automated sample processing...

We describe a rapid, precise, cost-effective, and accurate isocratic liquid chromatographic (LC) procedure for determining cyclosporine in whole blood. The cyclosporine is extracted from 0.5 ml of whole blood together with 200 micrograms of cyclosporin D, added per liter as internal standard, by using an Advanced Automated Sample Processing (AASP) unit. The on-line solid-phase extraction is performed on an octasilane sorbent cartridge which is interfaced with a Perkin-Elmer 83 X 4.6 mm I.D. cartridge column, packed with 3-micron octadecyl packing. The column is eluted with a mobile phase containing acetonitrile-water (13:7) at a flow-rate of 1.0 ml/min at a column temperature of 70 degrees C. The column effluent is monitored at 210 nm. The absolute recovery of cyclosporine exceeded 87% and the linearity extended up to 2000 micrograms/l. Within-run and day-to-day coefficients of variation were less than 8%. The correlation between AASP-LC and manual Bond-Elut extraction-LC method was excellent (r = 0.97).