Improved Solvents for Paper Chromatography of Thiazine Stains

Abstract

Paper chromatography with new solvents applied to some commercial samples of thiazine stains, especially azures, resulted in improved resolution which gave more spots than had been obtained with previously reported solvents. To a Whatman No. 1 filter paper strip, 50 cm in length, 0.08 ml of a 0.1% solution in water was spotted 18 cm from the edge of the strip. The solvent used in most cases was a mixture of t-butylalcohol, methylcellosolve and a 1% NH₄Cl solution in distilled water (60:20:20, v/v) with the ascending technique. Several batches of thionin were found to have a high degree of purity (concerning their content of coloured components). One sample of thionin (Chroma) contained only one component (violet). The thionin-SO₂ reagent showed a chromatogram with more spots than the thionin sample from which the reagent was prepared. Qualitatively a sample of azure A appeared to have practically the same composition as a sample of azure C. At least six spots were visible in the chromatogram of these azures, which contain thionin in addition to the other components.