Mucin/carbopol matrix to immobilize oxalate oxidase in a urine oxalate amperometric biosensor Original Research Article

An enzymatic amperometric electrode with extended analytical range and improved stability for oxalate determination has been developed. Glutarlaldehyde/mucin/carbopol matrix was used for the crosslinking of the enzyme between polymeric membranes to form a classical laminate construction (sandwich) and compared with the glutaraldehyde/mucin/enzyme and glutaraldehyde/albumin/enzyme. The use of a sulphonated membrane as internal membrane allowed rejection of the most important electrooxidable urine interferents. The recovery assays were highly satisfactory. The wide linear response in the range 2–400 μM after 1/10 urine dilution (corresponding to 20–4000 μM) made it suitable for clinical range. High correlation with the standard spectrophotometric method was obtained (r2 = 0.98, y = 0.89x, n = 25).