Spectrophotometrical study on the preservation of sodium nitroprusside in aqueous solution [ETUDE SPECTROPHOTOMETRIQUE DE LA CONSERVATION DU NITROPRUSSIATE DE SODIUM EN SOLUTION AQUEUSE]
Résumé
Stability of sodium nitroprusside (SNP) in aqueous solution, submitted to different conditions of conservation, has been studied for a 3 months period. The titration methods involve the determination of nitrites and pentacyanoferrate complex in free and combined forms. This determination allows to follow the dissociation and the degradation of sodium nitroprusside. The conclusion of this work is that the stability of sodium nitro-prusside in aqueous solution, for a long period and in presence of molecular oxygen is remarkable for low temperature and darkness, and is also very good in usual laboratory conditions when the sample is preserved in tinted glassware. Addition of an adjuvant like citric acid trisodium salt is not necessary. It does not improve the sodium nitroprusside stability in aqueous solution. In other conservation conditions, degradation phenomena, essentially linked with the pentacyanoferrate reactivity, are noticed.