title: Letter: Colorimetry of procainamide.
mesh_terms: D003124:Colorimetry / Q000379:methods; D005069:Evaluation Studies as Topic; D006801:Humans; D007202:Indicators and Reagents; D009573:Nitrites; D011342:Procainamide / Q000032:analysis*
chemical_list: D007202:Indicators and Reagents; D009573:Nitrites; D011342:Procainamide