DETERMINATION OF MELARSOPROL IN BIOLOGICAL-FLUIDS BY HIGH-PERFORMANCELIQUID-CHROMATOGRAPHY AND CHARACTERIZATION OF 2 STEREOISOMERS BY NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

The analysis of melarsoprol in whole blood, plasma, urine and cerebros pinal fluid is described. Extraction was made with a mixture of chloro form and acetonitrile followed by back-extraction into phosphoric acid . A reversed-phase liquid chromatography system with ultraviolet detec tion was used, The relative standard deviation was 1% at concentration s around 10 mu mol/l and 3-6% at the lower limit of determination (9 n mol/l in plasma, 93 nmol/l in whole blood, 45 nmol/l in urine and 10 n mol/l in cerebrospinal fluid). Melarsoprol is not a stable compound an d samples to be stored for longer periods of time should be kept at -7 0 degrees C. Plasma samples can be stored at -20 degrees C for up to 2 months. Chromatography showed that melarsoprol contains two component s. Using nuclear magnetic resonance spectroscopy the two components we re shown to be diastereomers which slowly equilibrate by inversion of the configuration at the As atom.