Potassium permanganate solutions stability

Rees, T., The Stability of Potassium Permanganate Solutions, J. Chem. Educ., 64, 1058, 1987. 

The urine sample is diluted with 10 mL nitric acid (1.5%), 100 p.L potassium permanganate solution, 5% in water (for stabilization), and 50 p,L octanol (as an antifoaming agent) is added and the mercury vapor is released immediately from the sample by the induction of sodium borohydride solution (3% in 1% sodium hydroxide). Aqueous calibration standards can be used [100]. 

Potassium dichromate exhibits much greater stability in aqueous solution in comparison to potassium permanganate. Potassium dichromate possesses an inherent oranage colour that is not intense enough to serve its own end-point signal, specifically in the presence of the green Cr3+ ion, which is supposed to be present at the end-point. Hence, redox indicators are usually employed to locate the exact end-point e.g., barium diphenylamine sulphonate. 

A stock solution of 3.0% potassium permanganate in 10% nitric acid (prepared fresh daily) was used to stabilize the mercury collected in the rinses from the sampling train. The stabilized solutions were then returned to TraDets Columbus, Ohio laboratory for analysis. 

Tricresylphosphate from receptacle 9 enters flusher 11, which is a cylindrical apparatus with an agitator. First of all, tricresylphosphate is washed with 3% sodium hydroxide to neutralise residual hydrochloric acid and separate cresol (the allowable cresol content in tricresylphosphate is 0.6 g/1). It is also recommended to treat the product with diluted solution of potassium permanganate to improve the colour and oxidation stability of tricresylphosphate. 

In the original analytical method developed by Freudenberg and coworkers, wood was first subjected to alkaline hydrolysis at high temperature followed by a methylation with dimethyl sulfate The free phenolic hydroxyl groups were converted by this treatment to methoxyl groups and the phenolic units were thus stabilized toward oxidative breakdown The oxidation step was carried out by addition of portions of solid potassium permanganate at a pH at or near 7 until the purple color of the solution remained (Freudenberg et al 1936)... 

Stability and metal ion salt solubilities of the sila-crowns have not been quantitatively evaluated. The sila-17-crown-6 materials offer simple qualitative evidence of complex formation. Potassium permanganate is mixed with chlorobenzene. The salt rapidly settles and no coloration of the chlorobenzene is observed. The addition of 1-2% of the silacrown produces the characteristic deep purple color of solvated potassium permanganate. After 1 hour vinylsilacrown solutions turn brown and a fine percipitate is observed, presumbly due to silacrown promoted oxidation of its own vinyl group. 

Chemical stability of compounds K-1, K-2, K-3 and K-4 solutions to different chemical reagents during 90 day has been studied. For this purpose prepared films (thickness 200-300 microns) were lowered to the solution. After certain interval of time the films were took from a solution and checked external changes of sheets. The data of Table 7 show some swelling of samples after their stay in solutions 0.1% of potassium permanganate and 10% of nitric acid in which samples changed external parameters. 

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