4-(2-hydroxyethyl)-1H-pyrrole-3-carboxylic acid; Potassium Clavulanate - Impurity D (EP/BP); 4-(2-Hydroxyethyl)-1H-pyrrole-3-carboxylic Acid; 1H-Pyrrole-3-carboxylic acid, 4-(2-hydroxyethyl)-; 4-(2-Hydroxyethyl)pyrrole-3-carboxylic Acid