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

A novel optical method for the determination of thiram has been developed using surface plasmon resonance peak of gold nanoparticles (AuNPs). The stable and dispersed AuNPs were directly synthesized by reduction of HAuCl4 with ascorbic acid in micellar media according to a simple approach. The presence of thiram during formation of AuNPs results in the decrease of the intensity of plasmon resonance peak. The variation in the plasmon absorbance allows the colorimetric determination of thiram. The effect of different variables such as pH, ascorbic acid and CTAB concentrations was studied and optimized. The proposed method is capable of determining thiram over a range of 2.0×10(-7)-1.0×10(-5) mol L(-1) with a limit of detection 1.7×10(-7) mol L(-1). The relative standard deviation of the method was <3.7%. The method was successfully applied to the determination of thiram in water and plant seed samples.