The products of the AOx-based O2-scavenger are aldehydes resulting from the oxidation of the primary alcohols or formic acid resulting from the oxidation of formaldehyde when paraformaldehyde (or methanol) is used as substrate. The influence of the products on the activity of GOx was monitored by recording the catalytic current for glucose oxidation over time in an electrolyte containing glucose, GOx, Fc(MeOH)2 and the AOx-based O2-scavenging system. After 3 h, the catalytic current decreased only slightly when using alcohols as substrate for AOx (Figure ). These current decreases are comparable to the ones obtained in the absence of the O2 scavenging system when purging the electrolyte with Ar to remove O2. When using paraformaldehyde as substrate, the catalytic current for glucose oxidation steadily decreases over time, which closely follows the pH drop from 7.1 to 6.7 due to the generation of formic acid (Figure ). Nevertheless, this pH and activity decay is on the time scale of hours. otherwise. Scavenger contains AOx (10 U mL -1 ), CAT (2000 U mL -1 ), and paraformaldehyde (5 mg mL -1 ). The GCEs were modified with Os-complex modified polymer (50 wt%), GOx (40 wt%) and PEGDGE (10 wt%) with a total loading of 200 μg cm -2 .