High-performance liquid chromatographic determination of sodium nitroprusside

A rapid high-performance liquid chromatographic method for the determination of nitroprusside in commercial lyophilized products or in intravenous admixture solutions is described. The method is stability-indicating. Reversed-phase liquid chromatography was performed using a microparticulate (10 micrometer) phenyl column with a mobile phase acetonitrile--phosphate/tetrabutylammonium hydroxide buffer (pH 7.1) (30:70) and detection at 210 nm. A coefficient of variation of less than 3.1% was achieved over the concentration range studied (10--50 microgram/ml). Total analysis time was 9 min. This method was used to show that there is a small loss of nitroprusside due to photodegradation during intravenous infusion, even when the admixture container is wrapped in foil as recommended and used expeditiously.