Abstract
In connection with the studies on the chemical determination of pyridoxal-5-phosphate, the stability of its aqueous solution was examined by means of ultraviolet absorption spectroscopy. The absorption maximum of the solution was observed at 388mμ above pH 4.0 and at 299mμ below pH 3.0,whereas in the range of pH 6.0 to pH 8.0,the extinction at 290,330,350 and 388mμ did not significantly change. It was clarified that the aqueous solution being exposed to sunlight, pyridoxal-5-phosphate was decomposed to a certain extent and therefore, the stock solution must be kept in dark place. It was also ascertained that pyridoxal-5-phosphate was substantially stable, even though the solution was heated at 40℃ for 30 minutes.
