Catechol Dyes–Tyrosinase System for Colorimetric Determination and Discrimination of Dithiocarbamate Pesticides

A convenient and straightforward method, which is based on catechol dyes and tyrosinase, for colorimetric determination and discrimination of dithiocarbamate pesticides (DTCs) has been fabricated. Three catechol dyes, including pyrocatechol violet (PV), pyrogallol red (PR), and bromopyrogallol red (BPR), were chosen as both substrates and indicators in this method. Tyrosinase can facilitate oxidation of the catechol dyes, altering color and absorbance spectra of the dyes. DTCs can alter the absorbance spectra of the catechol dyes–tyrosinase system due to their inhibitory effects on tyrosinase. As a result, the detection limit of the PV–tyrosinase system on ziram was determined to be 4.5 μg L–1. By implementing PV–tyrosinase, PR–tyrosinase, and BPR–tyrosinase, the colorimetric array successfully distinguished six DTCs (thiram, ziram, diram, ferbam, metiram, and mancozeb) at 5.0 μM using principal component analysis (PCA). The system can also determine ziram and distinguish DTCs in real samples. Furthermore, a smartphone can be used as a detector in this system to improve its real-world applications.