Fluorescein mercuric acetate—A novel sensor for oral malodour detection

Volatile sulphur compounds (VSC) like hydrogen sulphide, methyl mercaptan and dimethyl sulphide are the primary constituents of oral malodour. We have developed a fluorimetric assay, using fluorescein mercuric(II) acetate (FMA), for the quantification of VSC in mouth air. The assay is based on the quenching of fluorescence of FMA on reaction with VSC. The detection limit of the sensor is 0.06 μg L−1 for VSC. The analyte concentration, the pH of solution and the time for reaction have been optimized to achieve rapid and sensitive response for VSC levels in the range of 0–0.75 μg L−1.The response of the sensor has been validated with a commercial halimeter. The sensor was also used to study the VSC levels in human subjects with healthy oral hygiene. The level of VSC in mouth air of healthy subjects ranged between 0.2 and 0.4 μg L−1. The assay can be a potential diagnostic tool to evaluate any change in the VSC levels in mouth air due to different environmental factors. The sensor is cost effective, sensitive and simple to use. It can be used for routine clinical evaluation of oral malodour and also as a self-test kit.