Abstract

Extraction of dyes from leather followed by spectrophotometric analysis is of technical and commercial importance. During the extraction process, vegetable tannins are co-extracted with the dyes and interfere during the subsequent spectrophotometric estimation of dyes. The interferences caused by vegetable tannins are eliminated by separating the anionic leather dyes as ion-pairs with tetra n-butylammoniumchloride in chloroform from the dye-tannin mixtures in 50% aqueous dimethylformamide prior to analysis.