Malachite Green Optical Sensor Based on Electrospun Polyimide Nanofiber

Malachite green (MG) is a triphenylmethane cationic dye used in aquaculture practice, although it has been banned in several countries. The illegal use by fish producers, however, persists due to its effectiveness, and ready and cheap supply. To prevent indiscriminate applications, strict control measures with simple analytical approaches are therefore necessary. With this purpose, a novel, cheap and simple method applying electrospun polyimide nanofibers was developed and validated for MG control in water by color image analysis. For detection, a simple apparatus and ImageJ (R) software to treat images captured by common smartphones were used. A detection limit of 0.013 mg/L with a linear analytical response range within the concentration of 0.05 to 0.3 mg/ L of malachite green (MG) with a correlation coefficient of 0.997 and standard deviation (n = 9) varying from 1.01 to 3.92% was achieved with the proposed method. Accuracy was assessed by recovery assays in water samples and percentages of 96.6 to 102.0% were obtained. The method is robust and suitable for the rapid and reliable monitoring of MG in water.