The voltammetric behaviour of 1 mM TB in 0.1 M H2SO4was ex-plored further as a function of a scan rate in order to acquire com-plementary insight into the nature of the electrode reaction of thisxanthine on the miniaturized BDDE using CV technique (Fig. 3). Thevariation of the scan rate from 5 to 300 mV/s resulted in a linear re-lationship between the oxidation peak current of TB (Ip) and the squareroot of scan rate (ν1/2), as evidenced in thefirst inset ofFig. 3and theequation (Eq.(1)) below: