Colorimetric determination of o-phenylenediamine in water samples based on the formation of silver nanoparticles as a colorimetric probe.

A simple, rapid and cost-effective method for visual colorimetric detection of o-phenylenediamine (OPD) based on the formation of silver nanoparticles (AgNPs) has been developed in this paper. Silver ions can be reduced to AgNPs by OPD in a few minutes, causing changes in absorption spectra and color of the reaction system. Therefore, colorimetric detection of OPD could be realized by a UV-vis spectrophotometer or even the naked eye. Results showed that the absorption intensity of AgNPs at 416 nm exhibited a good linear correlation (R2=0.998) with OPD concentration in the range from 10(-6) to 8×10(-5) mol L(-1) and the detection limit (3σ/S) was calculated to be 1.61×10(-7) mol L(-1). Furthermore, as low as 4×10(-6) mol L(-1)OPD can be visualized by the naked eye without the requirement of any complicated or expensive instruments. This proposed method has been successfully applied to determine OPD in water samples, and may provide an innovative platform in the development of sensors for guiding environmental monitoring in the future.