Abstract:

A process impurity (~ 4%, w/w) was isolated from losartan crude by low-pressure reversed-phase column chromatography. At first the elution portions containing the target compound were collected. After evaporation and recrystallization, the purity of the target compound was found to be over 99% based on high performance liquid chromatography with ultraviolet absorption. The electrospray ionization-mass spectrometry result showed that it was an isomeric compound of losartan, which had same fragmentation pattern with its parent compound. And at last the compound was further characterized by nuclear magnetic resonance. This research demonstrates that the low-pressure reversed-phase column chromatography can raise separation efficiency and recovery comparing with other conventional column chromatography, and the technique can be applied as an effective means for the enrichment and extraction of impurities in pharmaceutical separation.

Key words: isomeric compound, losartan, mass spectrometry, nuclear magnetic resonance spectroscopy , purification, reversed-phase column chromatography