Selective solid phase extraction and preconcentration of mercury(II) from environmental and biological samples using nanometer silica functionalized by 2,6-pyridine dicarboxylic acid

2,6-Pyridine dicarboxylic acid was immobilized on the surface of nanometer-sized silica to prepare a new solid phase extractant which was applied to extract and preconcentrate trace mercury(II) from aqueous solutions prior to the determination by inductively coupled plasma atomic emission spectrometry. The optimization of some analytical parameters affecting the recovery of the analyte such as acidity, shaking time, eluent condition, sample volume, sample flow rate, and influence of potentially interfering ions were investigated. At pH 3, the maximum uptake capacity for mercury(II) was found to be 92 mg g(-1). Quantitative recovery (a parts per thousand yen95%) of mercury (II) was achieved by stripping with 2 mL of 0.1 mol L-1 hydrochloric acid and 3% thiourea. The presence of several metal cations and anions, some of them in high excess, did not interfere with the separation of mercury (II) under optimal conditions. An enrichment factor of 175 and a relative standard deviation less than 3.0% (n = 8) were obtained for mercury(II) determinations. The detection limit (3 sigma) was 0.09 ng mL(-1). The method has been validated using certified reference materials (GBW 08303 and GBW 08301), and was applied to the determination of trace mercury(II) in environmental and biological samples with satisfactory results.