Molecular Formula H5IO6, Molecular Weight 227.934, Periodic acid for the periodic acid Schiff, or PAS reaction, is used for the decetion of mucopolysaccharides, glycogen, muco- and glycoproteins, glyco-, phospholipids, basal membranes and collagen. The material is treated with periodic acid Periodic acid creating aldehyde groups which react with Schiff's reagent and give a bright red color reaction, thus the nuclei appear blue.