File Name : figure s1. _a_.tif

Caption : effect of the square wave amplitude on the voltametric profiles. (a) response obtained at an amplitude of 75 mv, showing signal distortion and peak splitting. (b) response obtained at the optimized amplitude of 50 mv, exhibiting a well-defined and symmetric peak suitable for analytical measurements. signal identification:  copper background (▬); 0.7 mg/l an (▬), 3.5 mg/l an (▬), 7 mg/l an (▬), lines correspond to the increasing additions of the standard solution.

File Name : figure s1. _b_.tif

Caption : effect of the square wave amplitude on the voltametric profiles. (a) response obtained at an amplitude of 75 mv, showing signal distortion and peak splitting. (b) response obtained at the optimized amplitude of 50 mv, exhibiting a well-defined and symmetric peak suitable for analytical measurements. signal identification:  copper background (▬); 0.7 mg/l an (▬), 3.5 mg/l an (▬), 7 mg/l an (▬), lines correspond to the increasing additions of the standard solution.

File Name : figure s2. _a_.tif

Caption : (a) baseline-corrected swv responses (n = 3) obtained after injections of standard solutions containing increasing concentrations of an (0.014 to 0.07 mg/l) at 3d-cb/hec–ch@cu electrode, using 0.10 m borate buffer (ph 9) as the supporting electrolyte (- - -). (b) calibration curve of an (r = 0.997), obtained from the integration of the net peak areas, calculated by subtracting the copper background (▬) contribution from each signal. swv conditions: see fig. 4.

File Name : figure s2. _b_.tif

Caption : (a) baseline-corrected swv responses (n = 3) obtained after injections of standard solutions containing increasing concentrations of an (0.014 to 0.07 mg/l) at 3d-cb/hec–ch@cu electrode, using 0.10 m borate buffer (ph 9) as the supporting electrolyte (- - -). (b) calibration curve of an (r = 0.997), obtained from the integration of the net peak areas, calculated by subtracting the copper background (▬) contribution from each signal. swv conditions: see fig. 4.