Chitosan/Colloid Au Modified Gold Film Microelectrode For Iodide Determination

Iodine is one of the essential elements responsible for physical and mental growth in human beings. It is one of the indispensable elements for the synthesis of thyroid hormone which regulates cell metabolism and supports for the development and growth of the neuromuscular tissue (especially in the fetus brain). Both of iodine deficiency and iodine excess will cause great harm to human health. Conventional determination methods include chromatography, atomic spectrometry, spectrophotometry, neutron activation analysis, inductively coupled plasma mass spectrometry (ICP-MS), chemiluminescence method. All of them either require expensive and sophisticated equipment or reach poor sensitivity. However, electrochemical method is widely applied for high sensitivity, fast response time, and specificity. In order to meet people’s high demand for healthy concept in the new period, especially after the Fukushima nuclear disaster in Japan, it is very necessary to establish a sensitive and efficient, simple and easy electrochemical method for iodide analysis.This paper provides a simple electrochemical method for iodide detection using chitosan\colloid Au modified gold film microelectrode. Chitosan is a kind of high molecular compound. It contains a huge number of reactive groups, such as hydroxyl (-OH), amino group (-NH2), etc. In acidic conditions-NH2could be protonated into-NH3+which has a strong electrostatic attraction with I-, and then I-could be detected by voltammetric method. The sensing performance of the chitosan/colloid Au modified gold film microelectrode toward iodide was evaluated in a0.1mol·L-1KH2PO4(pH=2.5) solution and the obtained voltammetric response increased proportionally with iodide concentration in the range of3.32×10mol·L-1～1.57×10-2mol×L-1with a correlation coefficient of0.9996. The detection limit was1.20×10-7mol·L-1(3S/N).The chitosan/colloid Au modified gold film microelectrode is more sensitive compared with commercial iodide selective electrode, especially at lower concentration. It was also evaluated by analyzing iodide ion content in a commercial dietary supplement and satisfying results compared with the spectrophotometric method were obtained. With MEMS (micro electro mechanical system) processing technology and microfluidic technology, it is of great potential for rapid, online and sensitive for iodide determination.