Pyrolysis Gas Chromatography of Wool

Abstract

Pyrolysis gas chromatography was used to study the content of tyrosyl residues in wool and the depletion of those residues by chemical reaction with nitrous acid. Wool samples that had undergone nitrosation of varying duration were analyzed by Curie- Point pyrolysis coupled with capillary column GC and flame ionization detection. The inertness of phenylalanyl residues to nitrosation permitted phenylalanine to be used as an internal standard. Peak areas for phenol and para-cresol—pyrolysis prod ucts—were compared to peak areas for phenylacetonitrile—a pyrolysis product of , phenylalanine. There was a linear relationship between the ratio of those peak areas and the molar ratio of Tyr / Phe, as determined by amino acid analysis, and another linear relationship for mixtures of known composition of polypeptides poly-tyrosine and poly-phenylalanine, but with a large difference in the slope from the line generated from the wool data. The difference was probably related to the relatively high con centration of terminal phenylalanyl groups in the polypeptide, which would result in the production of relatively larger amounts of phenylacetonitrile in the synthetic ma terial than in wool. The overall results demonstrated that damage to tyrosyl residues during the chemical processing of wool may be easily assessed using pyrolysis gas chromatography.