A Highly Sensitive Modified Glassy Carbon Electrode with a Carboxylated Multi-walled Carbon Nanotubes/Nafion Nano Composite for Voltammetric Sensing of Dianabol in Biological Fluid.

The extraordinary prerequisite for the analysis of an anabolic steroid, namely dianabol (DB), has inspired towards the development of a cost-effective and high-performance sensing probe. Thus, a simple and robust electrochemical sensor (c-MWCNTs-NafionlGCE) for dianabol (DB), a widely used steroid, was developed using a glassy carbon electrode (GCE) modified with functionalized carboxylated multi-walled carbon nanotubes (c-MWCNT) and Nafion. At pH 7 - 8, differential pulse-cathodic stripping voltammetry (DP-CSV) displayed two cathodic peaks at -0.85 and -1.35 V that varied linearly over a wide range (9.0 × 10 (2.7 μg L) - 9.0 × 10 (2.7 × 10 μg L) mol L) and 2.9 × 10 (8.7 × 10 μg L) - 8.0 × 10 (2.4 × 10 μg L) mol L) of DB concentrations, respectively. The low limits of detection and quantification at peak I (-0.85 V) were 2.7 × 10 (8.1 × 10 ng mL) and 9.0 × 10 (2.7 ng mL) mol L, respectively. The repeatability and reproducibility displayed relative standard deviations lower than 5%. The method was applied for DB analysis in human urine and subsequently compared with the standard HPLC method. Interference of common metabolites in biological fluids samples to DB sensing was insignificant. This method has distinctive advantages e.g. precise, short analytical time, sensitive, economical, reproducible and miniaturized sample preparation for DB analysis in biological samples of human origin.