Indirect electrochemical determination of ciprofloxacin by anodic stripping voltammetry of Cd(II) on graphene-modified electrode

• An electroanalytical method for CIP is developed based on CIP interacting with Cd2+.
• Anodic stripping voltammetry of Cd2+ provides sensitive indicating signal for CIP.
• Anodic stripping signal of Cd2+ at −0.72 V endows the method with good selectivity.
• The method is applied to CIP determination in pharmaceutical tablet and human urine.

An indirect electrochemical determination method for ciprofloxacin (CIP) was developed based on the complexation of CIP with Cd2+. On graphene-modified electrode, Cd2+ showed a strong anodic stripping peak current response, which was efficiently prohibited in the presence of CIP. Thus, the anodic stripping peak current of Cd2+ was employed as the indicating signal for CIP determination, which was more sensitive than the direct electrochemical oxidation response of CIP. Some influence factors such as the modified volume of graphene, solution pH, accumulation time, complexation reaction time were systematically investigated. Under optimum conditions, the anodic stripping response of Cd2+ on the graphene-modified electrode was inversely proportional to CIP in the concentration range from 1.0 × 10−7 to 1.0 × 10−5 mol L−1 with a detection limit (3S/N) of 5.9 × 10−8 mol L−1. The method showed high selectivity, good reproducibility and was successfully applied to the determination of CIP in pharmaceutical formulation and human urine.