The current valued recorded at the time of 25 s was used as the analytical signal. A linear response from
53 to 394 mg L−1 O was achieved (Figure 5B), with a slope of 1.16 nA mg−1 LO and a LOD of 36 mg L−1 , calculated using the 3σ IUPACcriterion.Incomparisonwithinbatch experiments (slope of 6.8 nA mg−1 LO and LOD of 28 mg L−12), these calibration parameters were limited by the measurement conditions as well as by the flow cell and the
integrated reference and counter electrodes. Regarding the flow cell geometry and taking into account that the measurements were carried out under quiescent conditions, the available glucose in the flow cell (dimensions 4 × 4 × 0.5 mm; volumeof 8 μL) may be completely oxidized during the time frame of the analysis (30 s) taking into account the growth of the diffusion layer thickness of a diffusion-controlled electrochemical process. This may be contributing to the abovementioned decrease in sensitivity of the device. Nevertheless, the overall analysis time was reduced from 90 s in batch to 30 s and the estimated LOD was similar. In addition, the repeatability obtained for the three consecutive calibrations was as good as in the batch experiments, as can be seen in the errors bars in Figure 5B.