Thermogravimetric method for simultaneous determination of potassium and ammonium by thermal decomposition of nitritocobaltates(III) of alkali metals

The work presents a new method of simultaneous determination of ammonium and potassium, involving precipitation and thermal decomposition of K2Na[Co(NO2)(6)](H2O)-H-. and (NH4)(2)Na[Co(NO2)(6)](H2O)-H-.. Using a thermoanalyser coupled with a mass spectrometer, one investigated thermal decomposition of nitritocobaltates(III) in the argon atmosphere and identified the obtained gaseous products. Decomposition of ammonium-sodium nitritocobaltate(III) requires less time and is more rapid than that of the potassium-sodium compound. This fact has been utilised to develop a thermogravimetric method for the determination of potassium and ammonium. The proposed method is very simple and is based on the determination of the loss in the mass of the nitritocobaltate(III) precipitate. The analysis results are calculated from the calibration plot constructed for the two-component system. The method has been applied to the analysis of urine.