An Improved Electrical Conductivity Method for Accurately Following Changes in the Respiratory Quotient of a Single Biological Sample

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Abstract
A new microrespirometer vessel is described, in which CO2 is measured by absorption in NaOH and the change in electrical activity of the NaOH is used as a measure of the CO2 produced. Simultaneously, the O2 consumed is followed on a manometer. The method makes it possible not only to follow the R. Q. of a single biological sample but to measure the change of the R. Q. with time. Calibration data are furnished relating the change in electrical conductivity of 0.05 N NaOH to the [mu]l. of CO2 absorbed per ml. of NaOH. The change of the calibration constant with temp, is given over the range of 5 to 40[degree]C. A simple A. C. bridge suitable for such measurements is described. An expt. using the apparatus with yeast-respiring alcohol and the change in R. Q. resulting from the addition of glucose is described.