Highly sensitive ‘naked-eye’ colorimetric detection of thiourea using gold nanoparticles

Abstract

Thiourea (TU) has been widely used in agriculture, industry and other application fields. Due to its serious toxicity and hazard to the environment, it is necessary to find a sensitive and selective method for detecting thiourea. Herein, a facile, fast, and specific colorimetric method was established for the determination of thiourea with high sensitivity based on leaching of gold nanoparticles (Au NPs) by thiourea. In hydrochloric acid media, the absorbance of the Au NPs at 519 nm decreased with the increase in the concentration of thiourea. The color change of the Au NPs with different concentrations of thiourea could make it convenient to be observed by the naked eye. This method allowed the determination of thiourea in the range of 5–350 nM with a detection limit of 2.14 nM. Various foreign species did not interfere with the determination. This method was found to be sensitive and selective and was applied for the determination of thiourea in natural water, industrial waste water and fruit juices.