Retention behavior of polycyclic aromatic hydrocarbons in supercritical fluid chromatography on a chemically bonded stationary phases based upon liquid-crystalline polymer

The retention behavior of a set of polycyclic aromatic hydrocarbons in supe rcritical fluid chromatography have been studied on a chemically bonded sta tionary phase based upon a side chain liquid crystalline polymer (LCP) with carbon dioxide-based mobile phase. The effects of the mobile phase pressur e, column temperature and amount of mobile phase organic modifier have been investigated in order to detect a possible structural change in the liquid crystal polymer linked to the silica support. The influence of these facto rs on the selectivity coefficients has also been studied. Two distinctive b ehaviors with temperature are noted at low pressure on the one hand and at higher pressure on the other This change in behavior is based on the densit y of the supercritical CO:! and the PAH volatility rather than on any speci fic stationary phase structural change. Both lower mobile phase pressure an d amount of mobile phase modifier are required to obtain better selectiviti es. Better planarity recognition is observed in SFC than in HPLC with these new bonded liquid crystal stationary phases. The bonded liquid crystal pha se is only weakly affected by the addition of organic modifier in the super critical CO2.d