Spectrofluorometric Turn-Off Sensing Probe for Tolmetin Determination Using Cerium and Nitrogen Codoped Carbon Dots.

A facile, low-cost, and rapid method was developed for spectrofluorometric determination of tolmetin (TOL) using highly fluorescent (QY = 35%) cerium and nitrogen codoped carbon dots (Ce-NCDs) sensing platform prepared by one-step hydrothermal method. Owing to the severe overlap between TOL absorption and Ce-NCDs excitation spectra around 320 nm, TOL could attenuate the emission of Ce-NCDs at 407 nm through primary inner filter effect (IFE). This concentration dependent attenuation was linear between 2 and 10 μg/mL (r = 0.9993) with a limit of detection of 0.5 μg/mL. The sensor showed very good accuracy (% recovery = 98%-100%) and precision (%RSD < 2). The developed sensing strategy was successfully applied for TOL detection as an active pharmaceutical ingredient in pharmaceutical formulation and as a potential pollutant in environmental water samples, such as tap and river water, with acceptable recovery and considerable selectivity. Thus, the direct single-step spectrofluorometric determination of TOL was enabled without extensive processing or chemical derivatization.