In this study an impedimetric immunosensor was developed in order to determine ciprofloxacin (CIP) in wastewater samples, an emergent contaminant widely found in wastewater. To achieve this, an anti-ciprofloxacin antibody was immobilized on the surface of a printed carbon electrode. Then, the developed immunosensor was applied in wastewater samples from Université Laval residences (Québec, Canada) through the load transfer resistance (R ct) using [Fe(CN)6]3-/4- as a redox probe, and the average CIP concentration was found to be 2.90 × 10-4 μg mL-1. The observed R ct changes presented a linear relationship from CIP concentrations of 10-5 to 1.0 μg mL-1, with detection and quantification limits of 2.50 × 10-6 and 7.90 × 10-6 μg mL-1, respectively. The immunosensor presented high selectivity and repeatability, as well as a good recovery rate in wastewater samples (97%). Significant interference with other compounds was not observed. The proposed method requires only 30 μL of sample without the use of organic solvents or preceding sample preparation and/or extraction techniques. Moreover, the method is fast: only 20 min of incubation followed by 2 min of analysis time was sufficient to obtain the CIP concentration. The method's estimated cost is U$ 2.00 per sample.
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