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.