The use of 'CO2 buffers' in manometric measurements of cell metabolism

Abstract

A mathematical theory is given of Pardee''s (Jour. Biol. Chem. 179: 1085. 1949)"CO2 buffers" which are designed to maintain an approx. constant CO2 pressure in manometer vessels in which CO2 is produced or absorbed. The theory is based on simplifying assumptions and indicates how the dissociation constants and the concn. of the base, and the CO2 pressure, affect the efficiency of the buffer. The buffering capacity or "retention" of various bases was measured at 25 and 40[degree] for CO2 pressures between 1 and 5.7%. Diethanolamine solns. were found to be the best general CO2 buffers. Their effectiveness may be increased by various additions. Diethanolamine solns. absorb measurable quantities of O2. The autoxidation is inhibited by dithizone or thiourea. Controls are required in each exptl. series in order to allow for the O2 uptake of the CO2 buffer. Absorption of CO2 exceeding 95% is obtainable at low CO2 concns. (1 or 2%) when traditional Warburg manometer vessels are used. With the vessels of Dickens and Simer, allowing the use of several ml. of CO2 buffer, absorption over 95% is possible for gas pressures up to 4%. Particulars concerning the prepn. and use of CO2 buffers and examples showing their efficiency are given.