Surface plasmon-assisted catalytic reduction of p-nitrothiophenol for the detection of Fe by surface-enhanced Raman spectroscopy.

Herein, we developed a concise, time-efficient, and high selective assay for detecting Fe through its triggered surface plasmon-assisted reduction reaction of p-nitrothiophenol (PNTP) to p,p'-dimercaptoazobenzene (DMAB) on the surface of gold nanoparticles (AuNPs) based on surface-enhanced Raman scattering (SERS) spectroscopy. When Fe was added to the PNTP-AuNPs system, the appearance of three characteristic peaks at 1142, 1392, and 1440 cm attributed to DMAB demonstrated that Fe induced the catalytic coupling reaction of PNTP. The Raman intensity ratio of the peak at 1142 cm to the peak at 1336 cm and the concentration of Fe presented a good linear response from 10 to 100 μM with a limit of detection (LOD) of 0.35 μM. More importantly, the entire detection process can be completed within 2 min and further successfully used for the detection of Fe in river water.