Micro cobalt electrodes for detection of total phosphorus in water

In this study, the characterisation and calibration of microfabricated cobalt electrodes for the detection of total phosphorus (TP) in water are presented. The microelectrode chips were fabricated by microelectromechanical systems technology, and cobalt was used as the sensing material modified on the surface of microelectrodes using the electrodepositing method. The surface morphology and crystal direction of modified cobalt were examined and the electrochemical characterisation of cobalt electrodes was performed. The cobalt microelectrode showed good linear response to phosphate in the range of 10^-6-10^-2 M/l with the slope of about 28 mV/dec. The microelectrodes also presented good stability, consistency and reproducibility. These electrodes were applied to detect TP concentration in water samples from a lake. Calibration was performed for each electrode before the test. The test result using these cobalt microelectrodes was consistent with the concentration given in the certificate of qualified water of the quality detection institute.