Tellurite Carbon Paste Sensors: Microscopic Analysis Provides New Insights on the Nature of the Interaction Between the Ionophore and Analytical Species

In this work, scanning electron microscopy (SEM) was used for the characterization of chemically modified carbon paste sensors (CMCPSs), with the aim of understanding their chemical and electrochemical properties. The work also provides a microscopic study on the role of the binder, type of carbon, amount and nature of modifier, composition of the carbon paste and its impact on the electrochemical performance of the sensor. In addition, energy dispersive X-ray spectroscopy (EDX) was utilized for the direct observation of the interaction between the chemical modifier and the carbon paste. This has enabled the fabrication of new sensitive and selective chemically modified carbon paste sensors that were successfully applied for the detection of tellurite ions in pure solutions, environmental and biological samples. This work provides new insights on the rational design and integration of carbon paste sensors for a variety of applications.