This method is used for the determination of the contents of potassium and sodium in sugar beet brei after extraction and defecation using lead acetate or aluminium sulphate respectively. For ecological and health reasons, the defecation using lead acetate should be avoided whenever possible. The method is applicable to all clear dissolved samples of sufficiently low viscosity. The ranges of measurement as described here are (3 to 80) mmol/kg beet for potassium and (1 to 50) mmol/kg beet for sodium. Statistical data on the repeatability and reproducibility of the method were elaborated by conducting an international collaborative study. ....