Fabrication of gallium hexacyanoferrate modified carbon ionic liquid paste electrode for sensitive determination of hydrogen peroxide and glucose

Gallium hexacyanoferrate (GaHCFe) and graphite powder were homogeneously dispersed into n-dodecylpyridinium hexafluorophosphate and paraffin to fabricate GaHCFe modified carbon ionic liquid paste electrode (CILPE). Mixture experimental design was employed to optimize the fabrication of GaHCFe modified CILPE (GaHCFe-CILPE). A pair of well-defined redox peaks due to the redox reaction of GaHCFe through one-electron process was observed for the fabricated electrode. The fabricated GaHCFe-CILPE exhibited good electrocatalytic activity towards reduction and oxidation of H2O2. The observed sensitivities for the electrocatalytic oxidation and reduction of H2O2 at the operating potentials of +0.8 and -0.2 V were about 13.8 and 18.3 mA M-1, respectively. The detection limit (S/N = 3) for H2O2 was about 1 mu M. Additionally, glucose oxidase (GOx) was immobilized on GaHCFe-CILPE using two methodology, entrapment into Nafion matrix and cross-linking with glutaraldehyde and bovine serum albumin, in order to fabricate glucose biosensor. Linear dynamic rage, sensitivity and detection limit for glucose obtained by the biosensor fabricated using cross-linking methodology were 0.1-6 mM, 0.87 mA M-1 and 30 mu M, respectively and better than those obtained (0.2-6 mM, 0.12 mA M-1 and 50 mu M) for the biosensor fabricated using entrapment methodology. (C) 2014 Elsevier S.V. All rights reserved.