Colorimetric determination of thiram based on formation of gold nanoparticles using ascorbic acid

► A novel optical method for sensitive spectrophotometric determination of thiram. ► First time ascorbic acid was used as reducer in detection method by AuNPs plasmon. ► The proposed method has a simple, fast and eco-friendly procedure. ► In contrast with citrate method, the AuNPs were formed in situ. ► The LOD is better than other methods based on spectrophotometric detection.