POTENTIOMETRIC METHOD FOR THE DETERMINATION OF ADENOSINE-5'-TRIPHOSPHATE

A potentiometric method for the determination of adenosine-5'-triphosphate (ATP) concentrations using a choline-sensitive membrane electrode and choline kinase enzyme is described. The choline electrode was constructed from a poly(vinyl chloride)-based membrane containing sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate as an ion exchanger and 2-fluoro-2'-nitrodiphenyl ether as a membrane solvent. Choline reacted quantitatively with ATP to produce the electrode-insensitive choline phosphate and, therefore, the concentration of ATP could be determined by the measurement of choline consumed by the enzymatic reaction. ATP down to 10 muM could be detected. This method was used successfully to determine the intracellular ATP content of human red blood cells.