A silver nanosol SERS quantitative method for trace F− detection using the oxidized tetramethylbenzidine as molecular probes

Fluoride constitutes an essential component for the formation of hard bones and teeth. However long-term excessive intake of fluoride causes chronic poisoning changes in the body. Therefore, the determination of its content is of great significance. Herein, a sensitive SERS quantitative analysis method was proposed to detect F − . Trace Fe 3+ exhibited strong catalysis of H 2 O 2 oxidizing 3, 3′, 5, 5′-tetramethylbenzidine (TMB) under the ultrasonic irradiation, and the reaction product called TMB diimine (TMB OX ) not only had strong fluorescence, but also had SERS activity in the silver nanosol substrate. Upon addition of fluoride ion (F − ), the stable complex of [FeF 6 ] 3− formed, and could inhibit the catalytic action of Fe 3+ , resulting in the SERS and fluorescence signal decreasing due to the TMB OX concentration decreasing. In the range of 2–1000 nmol/L F − , the SERS intensity Δ I decreased line with the concentration increased, with a detection limit of 0.7 nmol/L. Based on the catalytic amplifying strategy and the TMB OX molecular probes, ultratrace Fe 3+ could be also detected by SERS and fluorescence methods.