... -21-4 Appearance: White crystal powder 1-Hydroxy Ethylidene-1,1-DiphosphonicAcid (HEDP)CAS No. 2809-21 ... APHA (Hazen)30.0 max-Acetic acid %0.5 max Ca sequestration (mg CaCO3/ ... 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid; Hydroxyethylidene-1,1-diphosphonicacid(HEDP); 1-HYDROXYETHYLIDENEDIPHOSPHONIC ACID;Hydroxyethylidene Diphosphonic acid(HEDP); 1-hydroxy-1,1-Ethanediyl ester 1-Hydroxy Ethylidene-1,1 ...