Three-dimensional nano-structured silver on gold interdigitated microband array electrode for nitrate determination

摘要

A new type of micro amperometric sensing chip based on gold interdigitated microband array (Au-IDA) electrode for trace nitrate determination has been developed. The Au-IDA microelectrode is fabricated with micro-electro-mechanical systems technology. Three-dimensional (3D) nano-structured dendritic silver is electrochemically deposited on the Au-IDA microelectrode surface, which shows superior electrocatalysis property in facilitating nitrate reduction. The results show that the sensing chip has a sensitivity of 9.5 nA/μmol/L, limit of detection of 10 umol/L, detection dynamic range of 10-1000 μmol/L , and linear range of 25-1000 μmol/L nitrate (R~2=0.9998). Interference analysis with 9 kinds of ions (NO_2~-, F~-, PO_4~(3-), H2PO_4~-, SO_4~(2-), CO_3~(2-), NH_4~+, Na~+ and K~+) commonly found in surface water indicates that the proposed microchips have good selectivity to NO_3~-. It is noteworthy that the proposed 3D nano-structured dendritic silver modified Au-IDA microelectrode could be used for nitrate analysis in neutral media which is important for field and real-time monitoring nitrate ions in natural water.