A simple micromethod for the direct determination of the total carbon dioxide content in biological fluids

A simple method is presented for the determination of the total carbon dioxide content applicable to all biological fluids. This method makes use of a PCO2-electrode, placed in a perspex reaction/measuring chamber, connected with a IL blood gas analyzer, type 413 equiped with an electronic data-ready indicator system. The advantages of the proposed method are: 1. Depending upon the accuracy required for sera, the sample volume can be reduced to 20 or 10 μl. 2. A high degree of accuracy is obtained depending upon the sample volume used; for sera we calculated variation coefficients of 2%, 1% and 0.8% using sample volumes of 10, 20 and 30 μl, respectively. 3. The proposed method is simple and requires only two minutes for one determination. 4. In a comparative study an almost perfect relationship was found between the proposed method and the indirect method by calculation with a constant pK'ig value.