Mediated electrocatalytic voltammetry of human sulfite oxidase (HSO) is demonstrated with synthetic one electron transfer iron complexes bis(1,4,7-triazacyclononane)iron(III) ([Fe(tacn)(2)](3+)) and 1,2-bis (1,4,7-triaza-1-cyclononyl)ethane iron(III) ([Fe(dtne)](3+)) at a glassy carbon working electrode. The two synthetic electron acceptors for HSO, differing in redox potential by 270 mV, deliver different driving forces for electrocatalysis. Digital simulation of the catalytic voltammetry was achieved with single set of enzyme-dependent kinetic parameters that reproduced the experimental data across a range of sweep rates, and sulfite and mediator concentrations. Amperometry carried out in a stirred solution with the lower potential mediator [Fe(tacn)(2)](3+) was optimised and exhibited a linear increase in steady state current in the sulfite concentration range 5.0 x 10(-6) to 8.0 x 10(-4) M with a detection limit of 0.2 pM (S/N = 3). The HSO coupled electrode was successfully used for the determination of sulfite concentration in white wine and beer samples and the results validated with a standard spectrophotometric method. (C) 2016 Elsevier Ltd. All rights reserved.