Amperometric argentimetric and mercurimetric titration of sulfhydryl: Argentimetric titration

Results of amperometric argentimetric titrations at the rotated platinum wire electrode in ammonia buffers of cysteine, glutathione, thioglycolic acid and 2-mercaptoethanol are presented. The method gives satisfactory results with glutathione and 2-mercaptoethanol. Thioglycolic acid gives good results in the presence of sulfite but high results in its absence. Its disulfide can be titrated accurately in the presence of sulfite. In agreement with other workers it was found that cysteine yields high results. The error increases with increasing cysteine concentration and is reduced in the presence of 0.1 M sulfite. It becomes equal to zero at cysteine concentrations equal to or smaller than 5.10^-5M.