Subject(s)
Chromatography, High Pressure Liquid/methods , Drug Contamination/prevention & control , Drug Evaluation, Preclinical/methods , Spectrometry, Mass, Electrospray Ionization/methods , Tetrahydroisoquinolines/analysis , Tetrahydroisoquinolines/chemistry , Chromatography, High Pressure Liquid/instrumentation , Ions , Quinapril , Reproducibility of Results , Sensitivity and Specificity , Spectrometry, Mass, Electrospray Ionization/instrumentationABSTRACT
LC-UV scan of lisinopril revealed the presence of an unknown impurity (approximately 0.14%) at a relative retention time of 3.26 employing phosphate buffer-acetonitrile as binary gradient system while LC-MS analysis with binary gradient system comprising of a ammonia-ammonium acetate buffer (pH 5.0) and acetonitrile indicated it to be C31H41N3O7. The impurity was isolated by preparative HPLC utilizing a linear gradient of water and acetonitrile. The structural analysis of the isolated product by 1H, 13C NMR, mass spectroscopy and FT-IR revealed it to be a 4-phenyl butanoic acid derivative (CL) of lisinopril.
Subject(s)
Lisinopril/analysis , Ammonia/chemistry , Chromatography, High Pressure Liquid , Drug Contamination , Gas Chromatography-Mass Spectrometry , Magnetic Resonance Spectroscopy , Mass Spectrometry , Solutions , Spectrophotometry, Ultraviolet , Spectroscopy, Fourier Transform InfraredABSTRACT
The presence of unknown impurity of the order of 0.2% was identified in benazepril using liquid chromatographic technique employing binary gradient system comprising acetic acid and ammonia in water and acetonitrile as the mobile phase. LCMS data corresponds to hydroxylated benazepril (OHB) derivative possessing the molecular formula C(24)H(28)N(2)O(6). This impurity was isolated using isocratic system containing ammonium acetate and acetonitrile and the product was characterized using FT-IR, (1)H and (13)C NMR and mass spectroscopy to ascertain the structure of the impurity. The spectroscopic analysis revealed the presence of hydroxyl function on C(17) carbon atom of benazepril molecule. The plausible mechanism for the formation of OHB species is proposed.
