Measurement of Norfloxacin in Effluent Samples Using a Smartphone-Based Colorimetric Sensor

The measurement of antibiotics is of great importance. Therefore, in this research, a colorimetric sensor based on the reaction of ferric iron and norfloxacin and the formation of a black complex resulting from their reaction has been designed. For this purpose, all conditions were optimized using a one-factor-at-a-time method to achieve the highest sensitivity. Then, under optimal conditions (pH=3.0, contact time 60 seconds, iron concentration 100 ppm), the designed sensor showed a suitable linear range from 1 to 100 micromolar. The detection limit and quantification limit are 0.31 and 0.99, respectively. In the developed method, a smartphone and the analysis of green, red, and blue colors from the captured images were used as the analytical signal, thus the developed method also benefits from portability and low cost. Finally, the proposed method was used for the analysis of norfloxacin in three wastewater samples, and the results were compared with a standard method.