The Polarographic Estimation of Sulfydryl and Disulfide Groups in Wool

Methods for determining sulfydryl sulfur only and sulfydryl plus disulfide sulfur in intact wool are described. In the first case, the wool is allowed to react with an excess of an organic mercurial in a buffer containing urea at pH 7-8.5, while in the second case sulfite as well as urea is present in a buffer at pH 8.5. In both, the excess mer curial is determined polarographically. Two existing methods for the polarographic determination of sulfydryl plus disulfide sulfur in protein hydrolysates, namely amperometric titration with mercuric chloride and the use of the catalytic wave produced by cysteine and cystine in the presence of cobalt ions, have been adapted for the special case of wool. to cope with 10-100 mg. samples and 0.05-0.10 mg. samples, respectively. An indication of the reliability of the nonhydrolytic methods is also given.