The assemble of the multi-wall carbon nanotubes on the surface of C18 and its electrochemiluminescence analytical application

In this paper, it was found that the multi-wall carbon nanotubes (MWNTs) could be effectively assembled on the surface of C18 based on the strong hydrophobic interaction between MWNTs and C18. It was further found that, when the MWNTs/C18 composite was doped into the carbon paste microelectrode, it offered the powerful ability not only as the solid phase extraction materials but also as the conducting pathway to accelerate the electron exchange between the analyte, which were extracted and located within the C18 microparticles, and the electrode surface. Based on those findings, isoniazid was used as the model analyte to explore the electrochemiluminescence (ECL) analytical performance of this composite. Experimental results revealed that the composite showed rapid extraction process of isoniazid due to the powerful absorption ability of C18 and rapid electrochemical desorption process due to the conducting pathway effect of MWNTs. The highly selective and sensitive ECL determination of isoniazid was also achieved at MWNTs/C18 composite modified micro-carbon-paste electrode. Under the optimal experimental conditions, the ECL intensity was linear with the concentration of isoniazid in the range of 5.0 × 10^-8–9.0 × 10^-6 g/mL. The detection limit was 8.0 × 10^-9 g/mL. The proposed method has been successfully applied to the determination of isoniazid in the urine samples.