A Polarographic Study of Gallein

Gallein was polarographically studied in 40% ethanol solutions containing sodium carbonate or poassium biphthalate buffers at varying p H's. A well‐defined polarographic wave with E 1/2 ranging from −0.50 to −0.70 volt (S. C. E.) was observed in the p H. region 2∼ 6.6 while two waves with E 1/2 at −1.2 and −1.5 volts (S. C. E.) were observed in the pH region of 8.3 to 10.2 at 25°C. The former corresponds to a one‐electron reversible reaction while the latter ones may be irreversible. Gallein was polarographically determined in 40% ethanol solution over the concentration range of 3×10 −4 to 2×10 −5 molar.