ELECTRODE RESPONSES TO PHENOLIC SPECIES THROUGH CELLULOSIC MEMBRANES

The responses of an amperometric electrochemical cell to species of interest in the field of clinical biosensors, including hydrogen peroxide, ascorbate and phenolics were investigated. The effects of covering the electrode surface with polycarbonate and cellulose-based membranes on the response were determined, in order to assess the suitability of such membranes for use in biosensors. The addition of an amino or a further hydroxyl group in the ortho or para positions to a phenol group, enhanced the electroactivity of the phenolic group. A polycarbonate membrane of 2-mu-m pore size imparted no selectivity, with all phenolic, ascorbate and hydrogen peroxide electrode responses being 10-20% of the bare electrode value. Cellulose acetate membranes gave smaller responses, but were selective, being relatively more permeable to hydrogen peroxide and to phenol than to other phenolics, and excluding ascorbate to a large extent. Such membranes thus have a useful selectivity for use in certain biosensors. Cellulose acetate butyrate membranes showed a further reduction in signal size, but an unchanged pattern of selectivity.