Application of mobile phases containing ionic liquid for the analysis of selected psychotropic drugs by HPLC–DAD and HPLC–MS

In reversed-phase liquid chromatography, in case of the absence of additives, cationic basic compounds give rise to asymmetrical and broad peaks as a result of interactions of analyte cations with residual free silanols on silica-based stationary phases. Ionic liquids, added to the mobile phase, have been suggested as alternatives to amines to block the activity of free silanols. The different parameters affecting the retention behavior, symmetry of peak, system efficiency, and separation selectivity of selected psychotropic drugs, especially the effect of concentration of ionic liquid, kind and concentration of organic modifiers of mobile phases, and kind of stationary phases were investigated. The most selective and efficient systems are used for separations of psychotropic drug standardsu0027 mixture and for determination of selected psychotropic drugs in human serum.