The electrocatalytic activity of the modified electrode toward the
oxidation of insulin was studied by CV. CHNjCCE was also used in a homemade flow injection analysis
system for insulin determination. The limit of detection (signal/noise [S/N] ¼ 3) and sensitivity were
found to be 0.11 nM and 11.8 nA/nM, respectively. Moreover, the sensor was used for detection of insulin
in human serum samples. This sensor showed attractive properties such as high stability, reproducibility,
and high selectivity.