SEPARATION AND PRECONCENTRATION SYSTEM BASED ON MICROEXTRACTION WITH IONIC LIQUID FOR DETERMINATION OF MERCURY II IN WATER AND FOOD SAMPLES BY STOPPED-FLOW INJECTION SPECTROFLUORIMETRY

For the first time, an efficient in situ solvent formation microextraction (ISFME) was combined with stopped-flow injection spectrofluorimetry (SFIS) for the determination of mercury. In the proposed approach, thiamine was oxidized with mercury (II) to form hydrophobic and highly fluorescent thiochrome (TC), which was subsequently extracted into ionic liquid as an extractant phase. A small amount of an ion-pairing agent was added to the sample solution containing a water-miscible ionic liquid to form a hydrophobic ionic liquid. After centrifuging, phase separation was performed and the enriched analyte was determined by SFIS. ISFME is an efficient method for separation and preconcentration of metal ions from aqueous solutions with high ionic strength. The variables affecting the analytical performance were studied and optimized. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.035 μg L-1 and a relative standard deviation (RSD) of 2.5%. Finally, the proposed method was successfully applied to mercury determination in water and food samples.

Keywords:

In situ solvent formation microextraction , Stopped-flow injection spectrofluorimetry , Ionic liquid , Mercury