A novel enzyme sensor for the determination of inorganic phosphate

A new, highly sensitive enzyme sensor was developed for the determination of inorganic phosphate using maltose phosphorylase, acid phosphatase, glucose oxidase and mutarotase. The combination of the first two enzymes generates two glucose molecules per reaction cycle and recycles one molecule of phosphate. Finally, the oxidation of glucose is catalysed by mutarotase and glucose oxidase. The four enzymes were coimmobilized on a regenerated cellulose membrane which was mounted on the tip of a platinum amperometric electrode for the detection of enzymatically formed hydrogen peroxide. Thus, a detection limit of 10−8 M was obtained and the sensor response was linear in the range 0.1–1 μM, which is relevant for the monitoring of water pollution.