Graphite sheets modified with poly(methylene blue) films: A cost-effective approach for the electrochemical sensing of the antibiotic nitrofurantoin

Electroanalytical methods are suitable to quantify pharmaceutical compounds. The typically high cost for preparing many electrochemical sensors, however, has been a drawback to their widespread use. We have used inexpensive graphite sheets (GS) as conductive substrates, and modified them by electropolymerizing a film of poly(methylene blue) (PMB) by a simple, fast, and reproducible procedure based on potential cycling. The PMB film increased the sensitivity for nitrofurantoin (NFT) and provided an antifouling property to the electrode. Under optimized conditions, GS/PMB exhibited a current increase proportional to the concentration of NFT in the range of 5-100 mu mol L-1, with sensitivity and detection limit of 0.297 mu A/mu mol L-1 and 55 nmol L-1, respectively. The proposed sensor could successfully quantify NFT in tap water and urine samples. Considering the flexibility, lightweight, conductivity and surface properties of graphite sheets, and the vast number of monomers that can be electropolymerized at electrode surfaces, this approach may lead to the fabrication of several flexible, disposable, and portable devices with applications in electrochemical sensing and biosensing.

Automated summary

In this study, inexpensive graphite sheets were used as conductive substrates and modified to enhance the sensitivity for nitrofurantoin. The proposed sensor successfully quantified nitrofurantoin in tap water and urine samples.