A Rapid Electrochemical Technic for Measuring Carbon Dioxide Content of Blood

An electrochemical technic for measuring carbon dioxide (C02) content in whole blood has been devisedand evaluated. The method requires a membrane-covered pH electrode for the CO2 measurements. This electrode system permits rapid determi-nation of CO2 content in blood samplesof less than 1 ml. The measurement is per-formed by hemolyzingand acidifying a bloodsample in sucha manner that the released CO2 goes into physical solution. The increase of tension caused by this physically dissolvedCO2 is measuredby exposingthe sample to a previouslycalibrated electrode. While useof the technic requires some compromisewith accuracy (standard deviation of replicate samples = 0.76 volume/100 ml. compared with 0.12 volume/100 ml. for the Van Slyke manometric procedure), its convenience may outweigh this con-sideration in certain routine applications. SINCE 1934, when Stow and coworkers (1,.2) first described their membrane-covered electrochemical cell for measuring CO2 tension in l)lood, extensive application has been made of the concept of inserting a permeable l)arrier between a sample being measured and an electrod