Micellar electrokinetic capillary chromatography, high performance liquid chromatography and nuclear magnetic resonance—three orthogonal methods for characterization of critical drugs

2004 ◽  
Vol 35 (3) ◽  
pp. 459-467 ◽  
Author(s):  
Ralph Deubner ◽  
Ulrike Holzgrabe
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Magnetic Resonance ◽  
High Performance ◽  
Micellar Electrokinetic Capillary Chromatography ◽  
Capillary Chromatography ◽  
Orthogonal Methods ◽  
Electrokinetic Capillary Chromatography

Studies on the Stereochemical Characterization of N-Methylated Amino Acids

1991 ◽  
Vol 44 (11) ◽  
pp. 1591 ◽  
Author(s):  
SG Ang ◽  
SH Low
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Magnetic Resonance ◽  
Mobile Phase ◽  
High Performance ◽  
1H Nuclear Magnetic Resonance ◽  
Chiral Solvating Agent

Various methods that could be used to determine the absolute configuration of N,N- dimethylated amino acids were investigated. Two methods utilizing 1H nuclear magnetic resonance (N.M.R.) spectroscopy were successful. The first involved the conversion of the N,N- dimethylated amino acids into diastereoisomers by reaction with methyl (S)-(+)- mandelate . In the second method, the N,N- dimethylated amino acids were amidated with 3,5-dinitroaniline, and 1H n.m.r. analysis was carried out with the addition of a chiral solvating agent, (R)-(-)-1-(9-anthryl)-2,2,2-trifluoroethanol [(R)-(-)-atfe ]. Another method involving the use of high-performance liquid chromatography ( h.p.l.c .), with bis (L-aspartic cyclohexylamide )copper(II) complex CuII (L- Aspchex )2, as the chiral mobile phase was also examined but was found to be unsuccessful in resolving the D- and L-isomers of N,N- dimethylated amino acids.

scholarly journals Synthesis and Characterization of Tolvaptan Impurities

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Madhuresh Kumar Sethi ◽  
Vijendra Singh Rawat ◽  
Jayaprakash Thirunavukarasu ◽  
Rajakrishna Yerramalla ◽  
Anish Kumar
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Magnetic Resonance ◽  
High Performance ◽  
Mass Spectra ◽  
Synthesis And Characterization ◽  
Nuclear Magnetic

Twenty-six possible as well as observed impurities during the preparation of Tolvaptan have been identified, prepared, and characterized by HPLC (high performance liquid chromatography), NMR (nuclear magnetic resonance), and mass spectra. Control of these impurities, formed during various stages of Tolvaptan preparation, has been mentioned in this paper.

Sign in / Sign up

Export Citation Format

Share Document