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

• Gallium hexacyanoferrate modified carbon ionic liquid paste electrode was fabricated.
• Mixture experimental design was used to optimize electrode fabrication.
• Response trace plot was used to show the effect of electrode materials on response.
• The sensor exhibited electrocatalytic activity towards H2O2 reduction and oxidation.
• Glucose biosensor was fabricated by immobilization of glucose oxidase on sensor.

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 μM. 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 μM, respectively and better than those obtained (0.2–6 mM, 0.12 mA M− 1 and 50 μM) for the biosensor fabricated using entrapment methodology.