The surfactant, sodium dodecyl sulfate, promotes the redox reaction of hemoglobin. After the protein is acted on by the surfactant, hemoglobin gives good redox peaks even though the concentration is as low as 4 x 10(-7) mol/liter Hb. On the other hand, the negative effect pf the surfactant should also be considered, for sodium dodecyl sulfate is both a promoter and a saboteur for the redox reaction of the protein.