Researches on Glutathione

Part 6. Studies on the Iodometric Procedure among the Determination Methods of Glutathione. On the Iodometric Quantitative Estimation of Glutathione

Abstract

The present author examined the conditions for the iodometric quantitative estimation of glutathione (GSH) and discussed the iodometric methods proposed by Ogawa and Fujita and Numata.
GSH is estimated by iodine theoretically according to the equation 2GSH+2 I=GSSG+2HI, if the four conditions as shown in Table 2, 4, 5 and 6 are beep up. Particularly titration temp. is not always necessary to be kept at 0°C strictly as they prescribed, but it is desirable to be kept below 2°C. The effect of dilution factor is not necessary to be considered usually, if the above three conditions (Table 2, 4 and 5) are kept up.
Although Ogawa adopted the experimental value at the iodometric quantitative estimation of GSH, it is not correct from my experimental results and therefore it is to be revised as follows icc M/10000 KIO₃=0.1844mg GSH. And it must be further revised concerning exchange rate in the Ogawa's method which convert ascorbic acid value estimated by 2, 6-dichlorphenol-indophenol to GSH. This rate 4.1 given by him must be 3.5.