ABSTRACT
Development of a novel colorimetric and turn-on fluorescent sensor for potassium metabisulphite (KMS) using graphene oxide stabilized gold nanoparticles (GO-AuNPs) was described. The red color GO-AuNPs was changed to violet while adding 250â¯×â¯10-5â¯M KMS whereas the absorbance band at 523â¯nm was decreased. The observed changes were ascribed to the leaching of AuNPs from GO. The emission maximum was observed at 448â¯nm for GO while exciting at 335â¯nm. However, the GO emission was "turn-off" after the formation of AuNPs on GO surface due to masking of oxygen functional groups responsible for emission. Interestingly, the emission of GO-AuNPs becomes "turn-on" after the addition of 75â¯×â¯10-6â¯M KMS. Further addition of KMS from 150 to 1125â¯×â¯10-6â¯M, the emission intensity of GO-AuNPs linearly increases with the correlation coefficient of 0.9980 and the limit of detection was found to be 9.4⯵Mâ¯L-1/1.2â¯mgâ¯L-1 (S/Nâ¯=â¯3).