Effect of Room Temperature Ionic Liquid on the Formation of the Complex Oxalate-Sodium Morin-5-Sulfonate-Aluminium(III): Application to the Fluorescence Determination of Oxalate Ion.

The effect of room temperature ionic liquid (RTIL) on the formation of the fluorescence ternary complex oxalate-sodium morin-5-sulfonate (NaMSA)-Aluminium(III) has been studied. In weakly acidic medium and in the presence of RTIL, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), total complex formation is achieved as compared with the formation of the binary complex of NaMSA-Aluminium(III). The fluorescence characteristics of the system allowed the establishment of a very sensitive method for the spectrofluorimetric determination of oxalate ion. The ternary complex formed its highest fluorescence signal at 513 nm and excitation at 420 nm. In these conditions, the method produces a detection limit of 0.57 ng mL(-1). The procedure has been satisfactorily applied to the determination of oxalate ion in a vegetal tissue (spinach leaves).