The separation and analysis of gramicidin monomeric and dimeric species by packed column supercritical fluid chromatography

Gramicidin is a pentadecapeptide antibiotic which forms dimeric channels specific for the transport of monovalent cations in biological membranes. Presented here is a novel approach to the purification and analysis of gramicidin species using supercritical carbon dioxide (SC-CO2) based fluids. Under specified conditions, a relatively simple, rapid and environmentally compatible extraction method is obtained.;The separation of gramicidin species by packed column supercritical fluid chromatography (pSFC) is a second major focus of this research. The main monomeric components in gramicidin were successfully resolved on a PSDVB column using a CO2-based mobile phase. Additionally, the direct separation of the four principal double-helical dimeric conformers of gramicidin has also been achieved for the first time. The dynamic characteristics of the four principal conformers under different environments have been investigated systematically. The data show that pSFC can provide useful complimentary information to conventional methods of gramicidin analysis.