Metamizole Impurity 73H-Pyrazol-3-one, 1,2-dihydro-4-[(hydroxymethyl)methylamino]-1,5-dimethyl-2-phenyl-4-((Hydroxymethyl)(methyl)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-oneMetamizole Impurity 4Q: What is Metamizole Impurity 4 Q: What is the CAS Number of Metamizole Impurity 4