The Determination of Sodium in Body Fluids by the Glass Electrode*

The use of glass electrodes for the determina- tion of pH is well established. The possibility of measuring alkali ions in biological fluids by an electrode potential offers several advantages over other physical methods such as flame photometry (2). Since the publication of work by Eisenman, Rudin, and Casby (3) in 1957 demonstrating that the ternary glass system