A miniature and low-cost electrochemical system for sensitive determination of rhodamine B

There is an ongoing search to develop techniques for measurement of rhodamine B (RhB), an organic pollutant widely applied in many fields and presenting a serious threat to human health. In this study, a miniature electrochemical system was constructed to sensitively analyze for RhB by integrating a carboxylated multiwalled carbon nanotube and ionic liquid modified pencil-graphite electrode (MWCNTs-COOH/IL/PGE), an Ag/AgCl electrode, and a platinum wire all into a pipette tip. One distinct feature of this system was the small samples volumes from milliliter to microliter size needed for the analysis, which is critical when only small amounts of sample are available. Another advantage was the disposability of MWCNTs-COOH/IL/PGE and the pipette tip, which facilitated a practical in-situ measurement. The synergistic coupling effect between MWCNTsCOOH and IL fostered a high electrocatalytic activity of the sensor for RhB. Under optimum conditions, the oxidation peak current was linear with the concentration of RhB in the range of 0.005-2.0 mu M and 2.0-60.0 mu M. The lowest detection limit was found to be 1.0 nM. This study resulted in the development of a novel platform for the micro and ultra-sensitive measurement of RhB and provided great potential to simplify real-time environmental monitoring.