# Printable Carbon Black/Graphite Conductive Ink toward Electrochemical Determination of Norfloxacin in Environmental Samples

## TL;DR

A printable sensor made of carbon-based ink is developed to detect norfloxacin, an antibiotic contaminant, in environmental samples with high accuracy.

## Contribution

A novel conductive ink-based electrochemical sensor for detecting norfloxacin in environmental samples is developed and tested.

## Key findings

- The optimal ink composition for the sensor was found to be 33% graphite, 22% carbon black, and 45% stained-glass varnish.
- The sensor achieved a detection limit of 0.227 μmol L–1 and a quantification limit of 0.756 μmol L–1 for norfloxacin.
- The sensor demonstrated recovery values between 83.9 and 103.3% in real river water samples.

## Abstract

Norfloxacin (NOR), a fluoroquinolone antibiotic widely used to
treat urinary tract infections and gastrointestinal disorders caused
by bacteria, poses a significant environmental concern. The widespread
use of NOR can lead to the development of antibiotic resistance in
human populations and, upon release into the environment, can contaminate
aquatic and terrestrial ecosystems, potentially impacting human and
environmental health. This work aimed to develop an electrochemical
sensor printed with a conductive ink composed of graphite (Gr), carbon
black (CB), and stained-glass varnish (SGV) for the detection of NOR
in environmental samples. The optimal ink composition demonstrated
33% Gr, 22% CB, and 45% SGV. The morphology of the proposed sensor
was designed by scanning electron microscopy and Fourier transform
infrared spectroscopy, and electrochemical characterization was performed
by cyclic voltammetry and electrochemical impedance spectroscopy.
Differential pulse voltammetry was employed for NOR determination
using 0.05 mol L–1 Britton-Robinson buffer as the
electrolyte. Optimal current responses were obtained at pH 5.0. The
developed sensor presented a detection limit of 0.227 μmol L–1 and a quantification limit of 0.756 μmol L–1 for NOR, demonstrating high sensitivity, precision,
and accuracy. Furthermore, its application in real river water samples
provided recovery values between 83.9 and 103.3%. The sensor proved
suitable and stable for NOR determination in environmental samples.