A Method for the Determination of the Total Carbon Dioxide Content of Frozen Tissues

Abstract

A method is described for the determination of the total acid‐labile carbon dioxide of a tissue after freezing the tissue in situ with liquid nitrogen. The method utilizes a single diffusion step with the absorption of liberated carbon dioxide into hydroxide and subsequent titrimetric determination of the amount of carbon dioxide. Experiments performed on rat brain tissue showed that the transfer of the frozen tissue from liquid nitrogen to the diffusion chambers must be performed in an atmosphere which is free from carbon dioxide and water vapour. Control experiments have shown that if these precautions are taken, the total acid‐labile carbon dioxide can be accurately determined. Determinations of the total carbon dioxide content have been performed on 380 brains with 3–4 single analyses on each brain. Statistical analysis on the entire material shows that the total carbon dioxide content of a brain sample can be determined with a standard error of 0.06 ümoles/g if the sample weight is kept in the region of 40 to 150 mg.