LAUSR

This work describes a simple, rapid, and cost-effective method for fabrication of paper-based carbon electrode (US$ <0.01) using conductive ink based on powdered graphite and nail polish, supported on cardboard paper to sulfanilamide electrochemical determination by differential pulse voltammetry. The device was characterized by Raman spectroscopy, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Raman spectra showed the characteristic bands of graphite structures, D and G at 1350 and 1582 cm−1, respectively. SEM images revealed a porous and heterogeneous surface that contributes to the high electroactive area, while EIS demonstrated a greater ease of electronic transfer compared whit commercial glassy carbon electrode. The device presented a simple and highly reproducible construction process (RSD <5.7%). The method was applied to sulfanilamide determination in samples of lake and seawater, synthetic urine, otologic solution, and milk. The electrochemical method showed an excellent analytical performance with a detection limit of 4.1 µmol L−1, wide linear range from 10 to 100 µmol L−1, adequate precision (RSD <2.0%), and recovery values ranging from 80 to 102% for the spiked samples analysis and minimum sample preparation step (simple dilution). Thus, the disposable proposed device proves to be a promising analytical tool for in routine analyzes of clinical, environmental, and food samples.