Aqueous two phase system based on ionic liquid for isolation of quinine from human plasma sample

Abstract

Aqueous two phase system was applied for selective extraction of quinine from human plasma. Bi-phase was constructed from ionic liquid: butyl-methyl-imidazolium chloride after addition kosmotropic salts K3PO4 or KH2PO4. Quinine was determined in plasma samples after drinking of tonic containing quinine. Determination was performed by HPLC on 5-μm Zorbax SB-CN column and eluent containing 40% acetonitrile (v/v), 20mM phosphate buffer at pH 3 and 40mM NaPF6 using external standard method. The spectrophotometric detection was set λ=214nm. Selective fluorescence detection was performed at excitation of 325nm and emission of 375nm. Proposed strategy provides suitable sample purification and gives extraction yields in the range of 89–106%. The determination coefficient (R2) has a value ⩾0.997 in the range of 50–800ng/ml quinine concentration. The limit of quantification was set at 27.9ng/ml and the detection limit was found to be 8.4ng/ml under fluorescence detection.