Development of a perchlorate reductase-based biosensor for real time analysis of perchlorate in water

Perchlorate (ClO4−) contamination of ground water is a widespread problem in the U.S., which can adversely affect human health and wildlife. Current methods for detecting and quantifying ClO4− in water are time consuming, expensive and sometimes subject to complex procedures. This study reports the construction of a ClO4− reductase-based biosensor for rapid determination of ClO4− in water. Using a 3 mm GCE (glass carbon electrode), a ClO4− sensing bio-electrode was constructed by coating an aliquot of a Dechlorosoma sp. ClO4− reductase on nafion (ion-exchange matrix) layer pre-coated on the polished surface of the GCE. The response time to ClO4− was approximately 111 ± 28 s. Kinetic evaluation of the sensor response to ClO4− revealed linear increases (r2 > 99%) in 10 min with k values of 10.3, 24.2, 33.9 and 48.2 at 25, 50, 75 and 100 μg/L, respectively. A strong linear correlation was established between biosensor response (nA) and ion-chromatography conductivity readings (μS). Biosensor response to ClO4− was maximal at applied potential range of − 0.6 to − 1.0 V. ClO4− reduction was maximal in the range of 7.6 to 8.0. The ClO4− biosensor was significantly stable after repeated use (24 analyses conducted on day 1 over a 10-h period at room temperature). This study indicates great potential for the development of a portable biosensor for real time analysis of ClO4− in water.