The dye partition test for detecting carboxyl, sulphate and hydroxyl end‐groups in high polymers

Partition of a cationic dye between water and an organic solvent, the dye and the polymer being soluble in only water and the organic solvent respectively, has been utilized as a technique for detection of acid groups in a polymer. A coloration of the non‐aqueous layer takes place when anionic groups are present in the polymer. Detailed conditions for carrying out this test, to be called dye partition test, have been worked out for strong acid (sulphonate, sulphate, etc.) and COOH groups. The method has been extended for detection of OH groups. Some straightforward applications of this technique have been illustrated.