Low-cost paper-based electrochemical sensor for the detection of ciprofloxacin in honey and milk samples

In this paper, the simple process of manufacturing a paper electrode used for the electroanalytical quantification by differential pulse voltammetry of the antibiotic ciprofloxacin (CIP) in food samples is presented. The sensor was manufactured by employing a low-cost (lab-made) conductive ink composed of nail polish and graphite powder, supported by filter paper. The electrochemical device was characterized by scanning electron microscopy and cyclic voltammetry, where it was found that after the polishing procedure the electrochemical performance was improved by 33%. Furthermore, the proposed optimized method showed a wide linear working range ranging from 9.90 to 220 mu mol L-1, adequate sensitivity (LOD = 4.96 mu mol L-1), and selectivity towards other classes of antibiotics. The method was applied to monitor CIP in spiked samples of honey, whole and skim milk, with excellent precision (RSD < 3.1%) and adequate accuracy with recovery values ranging from 80% to 95%. Furthermore, the simple manufacturing process (disposable character) coupled with minimal sample treatment (simple dilution in supporting electrolyte) makes the paper sensor a promising tool for food control analysis.