1993 Volume 42 Issue 6 Pages 397-400
A sulfite ion enzyme sensor was prepared by cross-linking sulfite oxidase with bovine serum albumin using glutaraldehyde on the flat end of a platinum disk electrode silanized with 3-aminopropyltrimethoxysilane. Similarly, a phosphate ion enzyme sensor was made by coimmobilizing purine nucleoside phosphorylase and xanthine oxidase on the flat end of a glassy carbon disk electrode. A sulfite sensor was based on the amperometric detection (0.6 V vs. Ag/AgCl) of hydrogen peroxide produced by an enzymatic reaction; the current response was linearly related to the sulfite concentration over the range of 5×10-75×10-4 M. This sensor was highly selective for sulfite, except for a small response to nitrite, thiocyanate and thiosulfate. A phosphate sensor gave a response when inosine (5 mM) was added to a 0.1 M borate buffer solution (pH 7.5) containing phosphate. This sensor was based on the amperometric detection (0.5 V vs. Ag/AgCl) of uric acid produced by two successive enzymatic reactions. The current response was linearly related to the phosphate concentration over a range of 5×10-72×10-5 M at 37±0.2°C. This sensor was essentially specific for phosphate.
