Turn-on Fluorescence Hg2+ Chemosensing Based in a Rhodamine 6G Derivative and Different Sensing Immobilization Approaches

Abstract

In this study, the advantages and disadvantages of different immobilization approaches, proposed for a luminescent Hg2+chemosensor based in a spirocyclic phenyl-thiosemicarbazide Rhodamine 6G derivative (FC1), are analysed, and a comparative study of the different immobilization protocols is performed. The results demonstrated that the chemosensor is able to detect Hg2+ at ng mL-1 trace levels, with a remarkable selectivity, allowing its determination in biological, toxicological and environmental samples. Methyl methacrylate (MMA) and hydroxyethylmethacrylate (HEMA) polymeric film, electrospinning generated polymeric microfibres, nylon membranes and Au nanoparticles were tested as immobilization materials. The utilization of gold nanoparticles (AuNPs) is the method with the lowest limit of detection (LOD = 0.15 ng mL-1), but the response time is too high for practical use (7 hours). Nylon membranes give a very low detection limit (0.4 ng mL-1) and a practical response time (4 min), being the method of choice for practical applications to determine Hg2+ in aquatic, biological and toxicological samples, at a sampling rate of about 15 samples per hour.