DIRECT DETERMINATION OF MITOXANTRONE IN PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING AN AUTOMATIC PRECOLUMN-SWITCHING SYSTEM AS SAMPLE CLEANUP PROCEDURE

A high-performance liquid chromatography method which uses direct inje ction and a column-switching valve for determination of mitoxantrone i n plasma is described. After addition of internal standard, plasma was deproteinized by adding 5-sulphosalicylic acid reagent. The supernata nt was injected onto an enrichment precolumn flushed with washing solv ent (methanol and water 5:95). Absorbed mitoxantrone was backflushed f rom the precolumn into an analytical column C18 Nucleosil 250 x 4 mm w ith a gradient elution (solvent A, ammonium formate buffer 1.6 M, pH 4 .3; solvent B, acetonitrile and water 40:60; linear gradient from 45 t o 55% of B for 30 min was programmed) at a flow rate of 1.3 mL/min. De tection was carried out at 665 nm. This method showed obvious advantag es over conventional extraction procedures in terms of speed and facil ity of sample handling.