Figure 2. (A) Oxidation current after introduction at 3.5 min of 0.25 μL of urine spiked with glucose (final concentration = 26 mM) and a reference signal of blank urine without glucose (dotted line) using the system described. The voltage of the working electrode was 0.7 V vs Ag/AgCl, the area of the nitrocellulose strip (thickness = 140 μm) was 30 mm × 8 mm, and the distance between the site of sample introduction and the site of glucose oxidase was 20 mm. (B) Comparable experiment using a sample with a urinary glucose concentration of 0.8 mM. This sample represents the limit of detection for urinary glucose, with an absolute amount of only 200 pmol of glucose. Between these concentrations, the difference between the minimum before and the maximum of the glucose-related H2O2 signal (indicated in A) was linear in the glucose concentration. This difference in signal can be measured easily with a multimeter.