Control of retention mechanisms on an octadecyl-bonded silica column using ionic liquid-based mobile phase in analysis of cytostatic drugs by liquid chromatography

Abstract

This study assesses the potential of using ionic liquids (ILs) as mobile phase additives to control the retention mechanism of four cytostatic drugs: doxorubicin hydrochloride (DOX), epirubicin hydrochloride (EPI), daunorubicin hydrochloride (DAU) and idarubicin hydrochloride (IDA). Chromatographic separations were performed on a C18 analytical column (Discovery C18 150 × 4.6 mm, 5 µm) using six IL anions and four methyl-substituted IL cations with different alkyl chain lengths (alone or with the additional methyl group on the aromatic ring), or with an allyl group added as a cationic substituent. Thus, a total of 17 different ILs were assessed. The aqueous formic acid solution and phosphate buffer were used to compare how mobile phase composition affected the behavior of the analyzed cytostatic agents in the presence of ILs. In addition, the impacts of IL concentration, phosphate buffer concentration, and phosphate buffer pH on the final results were also considered. The ability to change analyte retention without negatively impacting peak shape or analytical efficiency was also controlled via the tailing factor and number of theoretical plates. Based on the results, the tested ILs were classified as either effective or ineffective mobile phase additives for separation of anthracyclines and identification by LC-FL technique.