Integration of a sensitive carbon nanotube composite electrode in a ceramic microanalyzer for the amperometric determination of free chlorine

In this paper we report a green tape ceramic microfluidic analyzer that integrates a complete amperometric detection system based on a highly sensitive carbon nanotube composite electrode. As a proof of the integration concept, reference and counter electrodes were embedded into the microanalyzer body during the fabrication process. In order to increase the system functionality, and taking advantage of the surface renewability associated with composite electrodes, the working electrode was integrated in an exchangeable configuration. The microanalyzer was automated by means of the multicommutation technique, which allowed its autocalibration by the on-line preparation of standard solutions from a unique stock solution. The system was applied to the analysis of free chlorine in water samples. A noticeable low detection limit (0.05 mg L−1) and a high-term stability were observed. To demonstrate the potentiality of this approach, in terms of analytical performance, it was also applied to the analysis of real samples obtained from a public swimming pool. The system characteristics make it ideal for unattended applications where the minimum user interaction and the maximum analyzer autonomy are required.