Isolation and characterization of a potential process related impurity of phenazopyridine HCl by preparative HPLC followed by MS-MS and 2D-NMR spectroscopy.
During the process development of phenazopyridine HCl bulk drug, a potential impurity was detected in the routine impurity profiles by HPLC. Using MS-MS and multidimensional NMR techniques, the trace level impurity was unambiguously identified to be 3-phenyl-5-phenylazo-pyridine-2,6-diamine after its isolation from phenazopyridine HCl by semi-preparative HPLC. The formation of the impurity was discussed. To our knowledge, it is a novel impurity not reported elsewhere.
Analytical Chemistry Division, Discovery Laboratory, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500607, India. rnrao@iict.res.in
R Nageswara
RN
Rao
Pawan K
PK
Maurya
A Narasa
AN
Raju
D000779:Anesthetics, Local / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004340:Drug Contamination; D017408:Guidelines as Topic; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D010621:Phenazopyridine / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
D000779:Anesthetics, Local; D010621:Phenazopyridine