Rhodamine-based fluorescent probe immobilized on mesoporous silica microspheres with perpendicularly aligned mesopore channels for selective detection of trace mercury(II) in water

A rhodamine-based organic-inorganic hybrid solid fluorescent chemosensor by covalently immobilized R6G derivative on core-shell structured mesoporous silica microspheres with perpendicularly aligned mesopore channels has been prepared. The fluorescent responses of the prepared chemosensor to Hg2+ have been investigated, and the results demonstrated that the proposed hybrid solid fluorescent chemosensor featured a high affinity Hg2+-specific fluorescence response in water by considering the highly dense modification of the rhodamine probe. The detection limit for Hg2+ is 0.1 nM (S/N = 3, which is well below the guideline value given by the World Health Organization) under optimized conditions. Excellent wide linear range (1.0-100.0 nM) and good repeatability (relative standard deviation of 3.2%) were obtained for Hg2+. The proposed chemosensor also exhibited excellent selectivity for Hg2+ over competing environmentally relevant metal ions, and can be used in a wide pH span and regenerated readily. These values, particularly the high sensitivity and excellent selectivity in contrast to the values reported previously in the area of fluorescent Hg2+ detection, demonstrated the analytical performance of the proposed chemosensor could be used for efficient determination of Hg2+ in natural water samples. Toward the purpose of practical application, the proposed chemosensor was further used to determine Hg2+ in real environmental water samples.