Sequential cyclic-square-wave voltammetric determination of sulfanilamide and ciprofloxacin in environment water samples using a 3D-printed electrochemical device

Sulfanilamide (SAD) and ciprofloxacin (CIP) are widely used antibiotics, and their indiscriminate use and disposal contribute to the increase in the contamination levels of aquatic environments. Herein, we propose a 3Dprinted carbon black/polylactic acid (CB/PLA) electrochemically activated electrode to determine CIP and SAD concurrently by cyclic square -wave voltammetry (C-SWV) technique. Firstly, square wave voltammetry measurements were performed exploiting the oxidation processes of CIP and SAD (Ox1CIP and Ox1SAD at around +1.3 V and +1.1 V vs. Ag|AgCl|KCl(sat.)). However, the lack of selectivity was verified in the analysis of water samples. Then, the C-SWV strategy was employed and enabled the selective determination of CIP (Ox1CIP) in the forward scan and SAD (Red1SAD) at around +0.5 V vs. Ag|AgCl|KCl(sat.)) in the reverse scan. Under selected C-SWV conditions, linear ranges from 4.96 to 40.61 mu mol L-1 (r = 0.9977) for CIP (Ox1CIP) and 1.99 to 10.78 mu mol L-1 (r = 0.9989) for SAD (Red1SAD) were obtained. The limits of detection for SAD and CIP were 0.2 and 0.6 mu mol L-1, respectively, and sensitivity was enhanced by 25 % for CIP and 60 % for SAD, employing the C-SWV protocol. In addition, this technique improves the selectivity once the analytes can be determined in distinct potential scans. Satisfactory recovery values ranging from 85 to 112 % were obtained in the analysis of spiked water samples (no dilution step), suggesting no pronounced matrix interference effect, and indicating that the C-SWV methodology ensures good accuracy. This work demonstrates that the union of 3D -printed CB/PLA electrodes and the C-SWV technique can enhance selectivity and sensitivity in the sequential analysis of CIP and SAD, and it is a promising strategy to monitor other pharmacological species in water samples.