Fig. 19From: PubChem chemical structure standardizationDifferences between PubChem-standardized and InChI-derived structures—protonation. Sulfuric acid is the most commonly deposited structure in PubChem. The structures shown in a with their SIDs are normalized to the protonated form of sulfuric acid b by InChI normalization but not by PubChem standardization, which does not alter them at allBack to article page