CdTe-paper-based Visual Sensor for Detecting Methyl Viologen

Abstract This study developed a method on detecting methyl viologen (paraquat) using a CdTe‐paper‐based visual sensor. The CdTe Qdots were immobilized on the paper using glycerin. The volume percentages of CdTe in glycerin were optimized to be 50%. The sensing principle is that the methyl viologen quenches the fluorescence intensity of CdTe Qdots in a concentration dependent manner. The sensor is linearly response to the logarithm concentration of the methyl viologen in the range from 0.39 µmol/L to 3.89 mmol/L with a detection limit of 0.16 µmol/L and the correlation coefficient R 2 of 0.99. Three parallel experiments at the methyl viologen concentration of 38.89 µmol/L give a relative error of 2.45%, which indicates a good reproducibility. The sensor is not disturbed by other pestisides including omethoate, anilofos, machete and glyphosate isopropylamine salt. The advantages of this sensor are disposable, stable, convenient, and easy to operate.