Jointly modified single-walled carbon nanotubes on low resistance monolayer modified electrode for arsenic(III) detection

Taking advantages of the larger specific surface area of single-walled carbon nanotubes and the lower contact resistance of –NH–C than that of multiple-walled carbon nanotubes and that of –S–Au, respectively, a ethylenediamine monolayer modified glassy carbon electrode (GCE) grafted by non-covalent and covalent sulphydryl groups jointly modified single-walled carbon nanotubes for arsenic(III) detection was developed. The resistance of ethylenediamine monolayer modified GCE was examined by electrochemical impedance spectroscopy. The characters of the non-covalent sulphydryl groups and the organized non-covalently modified single-walled carbon nanotubes were examined by detecting arsenic(III) and atomic force microscopy, respectively. After end-capped the remaining carboxylic groups of single-walled carbon nanotubes by covalent sulphydryl groups, the last electrode was applied to detect arsenic(III) and a limit of detection (LOD) (S/N = 3) of 0.008 μg L−1 was obtained. And also, common contaminants at levels presenting in natural water did not interfere with the assay.