The Titrimetric Assay of OH- and HCO3- Excreted by Ricinus Cultivated on NO3--containing Nutrient Media: The Influence of Ionic Strength, End Point pH and CO2 Supersaturation

Allen, S. and Allen, C. R. 1987. The titrimetric assay of OH^–and excreted by Ricinus cultivatedon -containing nutrient media: the influence of ionic strength, end point pH and CO² supersaturation.–J. exp. Bot. 38: 607–617. When spent -containing nutrient media were titrated to the starting pH of 6.5 the titre wasequivalent to 50%orless of the base (i.e. ) excreted. Calculation of the total amount of baseexcreted could only be made from data obtained by titrationto pH 4–5. An accurate calculation of the amount of baserequired the inclusion of activity coefficients, estimated fromionic strength, in the calculations. Spent nutrient media contained from four to ten times the concentrationof CO₂ predicted from equilibrium values. It is probable that is very slow. Key words: Ricinus, nitrate-N nutrient medium, base excretion, ionic activity coefficients, carbon dioxide supersaturation