Microdetermination of Nodososide and Related Compounds Using Ceric Sulphate as Oxidizing Agent
Nodososide and emodin from the flowers of Cassia nodosa and physcion-1-glucoside and physcion from the seeds of Cassia occidentalis can be determined in micro amounts by oxidation with eerie sulphate in presence of sulphuric acid. The reactions required 48, 26, 54 and 30 moles of oxidant respectively, resulting in the formation of formic and acetic acids in each case while carbon dioxide was also produced in the cases of nodososide and physcion-1-glucoside. The conditions of stoichiometric oxidation of the anthraquinones have been studied. Methylation of the hydroxyl groups has been found to retard the rate of oxidation of the anthraquinones whereas free hydroxyl groups are easily attacked by ceric ions. The ranges of errors observed are 0.2 -1.7%, 0.3 - 2.9%, 0.2 -3.5% and 0.2 - 3.5% respectively.