Decolorization on Freezing of Ferricyanide-Cyanide Solution used for Hemoglobin Determinations

Abstract

When Drabkin's solution (used for the determination of hemoglobin), which contains K₃Fe(CN)₆, KCN, and NaHCO₃, is frozen, it loses its greenish-yellow color. The solution remains colorless even after thawing. The reaction, for which there is no satisfactory explanation, involves the reduction of the K₃Fe(CN)₆ to K₄Fe(CN)₆, with KCN being oxidized to KCNO.