Synthesis of Poly-Amino Acid Ionic Liquid Up-Conversion Fluorescent Probe and its Application in Fe(II)/Fe(III) Speciation Analysis.

The poly amino acid ionic liquid (poly-1-vinyl-3-butylimidazolium glutamate acid, p-1-VbmGlu), with a stable up-conversion fluorescence(UCF) probe, was firstly prepared and the synthesis conditions were optimized. The UCF were found to be specifically quenched by Fe(III), but not respond to Fe(II). In H2O2 medium, Fe(II) posed strong quenching effect on the UFC owing to Fe(III) produced by redox between H2O2.and Fe(II). Therefore p-1-VbmGlu was employed as a UFC for Fe(II)/Fe(III) speciation analysis under the control of H2O2. The detection limits of Fe(II)/Fe(III) were 6.16 ng/mL and 4.48 ng/mL, with relative standard deviations of 1.1% and 2.0%, respectively. This method was successfully utilized in the analysis of Fe(II)/Fe(III) in multiple real samples.