Preparation and characterization of a carbon nanotube-based ceramic electrode and its potential application at detecting sulfonamide drugs

In this work, we report the construction, characterization, and the potential application of carbon-ceramic electrodes prepared with functionalized multi-walled carbon nanotubes (CCE/f-MWCNT) to detect two sulfonamide drugs: sodium sulfacetamide (SFC) and sulfadiazine (SFD). Prior to the construction of CCE/f-MWCNT, MWCNT samples were functionalized by using an acid treatment (HNO3/HClO4), and then characterized by FTIR spectroscopy, XRD, FESEM, and Raman spectroscopy. These techniques were also employed to characterize the prepared carbon-ceramic electrodes, and the obtained results demonstrated that the MWCNT were properly dispersed in the silica matrix. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy experiments showed that the f-MWCNT could enhance the electrochemical performance of the electrodes, as a consequence of its high electrical conductivity and large surface area. The antibacterial drugs were determined with CCE/f-MWCNT by employing CV and differential pulse voltammetry (DPV). A linear relationship between DPV peak currents and SFC and SFD concentrations was verified separately in the range from 9.9 to 177.0 A mu mol L- 1 in 0.04 mol L- 1 BR buffer solution pH 6.0. Detection and quantification limits were found to be 1.06 and 3.54 A mu mol L- 1 for SFC and 2.31 and 7.71 A mu mol L- 1 for SFD, respectively. Besides the good sensitivity, the CCE/f-MWCNT showed reproducibility and specificity, since its response was not significantly affected by the presence of electroactive interfering compounds. The promising analytical performance of the CCE/f-MWCNT was confirmed by determining SFC and SFD in commercial veterinary formulations, with percent recoveries ranging from 99.9 to 101.1% for SFC and from 99.8 to 102.2% for SFD. [GRAPHICS] .