A phenobarbital containing polymer/ silica coated quantum dot composite for the selective recognition of mercury species in fish samples using a room temperature phosphorescence quenching assay

Abstract

An analytical procedure using low-cost instrumentation (fluorescence/phosphorescence spectrophotometer) has been developed to assess total mercury in fishery products. Determinations were based on the room temperature phosphorescence (RTP) quenching of a composite Ph-QDs consisting of phenobarbital-containing polymer/silica coated Mn-doped ZnS quantum dots. Under optimum conditions (fish extract pH of 8.0, Ph-QDs concentration of 20 mg L−1, and an interaction time of 12 min), the material offers high selectivity for inorganic mercury and methyl-mercury over other common ions present in the fish matrix. Moreover, good linearity was obtained for mercury concentrations within the 0–100 μg L−1 range, and the obtained limit of detection (68.2 μg kg−1) is low enough for a reliable assessment of total mercury in fish and seafood samples. The developed method was found to be free of matrix effects, and offers the advantage that the fish extracts can be directly analysed even at a 1:10 dilution. The method was found to be accurate after analysing a fish certified reference material, and after comparing total mercury levels in a set of fish samples analysed by the proposed chemosensor probe and by inductively coupled plasma mass spectrometry after an acid decomposition sample pre-treatment.