Determination of thiram using gold nanoparticles and Resonance Rayleigh scattering method

A sensitive, simple and novel method was developed to determine thiram fungicide in water and plant samples. This method was based on the interaction between gold nanoparticles (AuNPs) and thiram fungicide followed by increasing of the Resonance Rayleigh scattering (RRS) intensity of nanoparticles. The change in RRS intensity (∆IRRS) was linearly correlated to the concentration of thiram over the range of 1.0-200.0µgL(-1). Thiram can be measured in a short time (4min) without any complicated or time-consuming sample pretreatment process. Parameters that affect the RRS intensities such as pH, concentration of AuNPs, standing time, electrolyte concentration, and coexisting substances were systematically investigated and optimized. Interference tests showed that the developed method has a very good selectivity and could be used conveniently for the determination of thiram. The limit of detection (LOD) and limit of quantification (LOQ) were 0.3 and 1.0µg L(-1), respectively. Relative standard deviations (RSD) for 20.0 and 80.0µg L(-1) of thiram were 3.0 and 1.1, respectively. Possible mechanisms for the RRS changes of AuNPs in the presence of thiram were discussed and the method was successfully applied for the analysis of spiked real water samples and fresh plant samples such as tomato and cucumber.