THE ELECTROCHEMISTRY OF HEMIN IN DIMETHYLSULFOXIDE

The electrochemistry of iron(III) protoporphyrin IX chloride (hemin) in dimethylsulfoxide (DMSO) was examined under both aerobic and anaerobic conditions. Under anaerobic conditions, two redox processes were observed {A figure is presented}, and a diffusion coefficient of 1.3 × 10-6 cm2 s was calculated for the iron(III) form of hemin. In the presence of oxygen, new peaks were observed, in particular a peak at -0.40 V evidently due to reduction of an oxygen adduct of hemin. This process occurs at a potential of about 0.4 V less negative than the reduction of oxygen in the absence of hemin. Spectroelectrochemistry, hydrodynamic voltammetry and chronocoulometry were used in conjunction with cyclic voltammetry to characterize the hemin redox system. Possible application of the system to the development of a porphyrin based oxygen sensor is discussed. © 1990.