Paraformaldehyde, as a solid reducing agent for AOx, proves practical for sensor fabrication and storage. In principle, it can be replaced with any short-chain alcohol, provided these alcohols can be stabilized in a gelled or solid form, releasing dissolved alcohol upon the addition of an aqueous sample. Methanol may be ideal, given its high rate of AOx-catalyzed oxygen reduction and the fact that its oxidation produces formaldehyde, which can further serve as a reducing agent for AOx in oxygen reduction.