Application of a new resin functionalised with 6-mercaptopurine for mercury and silver determination in environmental samples by atomic absorption spectrometry

Polystyrene-divinylbenzene (8%) has been functionalised by coupling it through an -N=N- group with 6-mercaptopurine. The resulting chelating resin has been characterised by using elemental analysis, thermogravimetric analysis and infrared spectra. The resin is highly selective for Hg(II) and Ag(I) and has been used for preconcentrating Hg(II) and Ag(I) prior to their determination by atomic absorption spectrometry. The maximum sorption capacity for Hg(II) and Ag(I) was found to be 1.74 and 0.52 mmol g(-1), respectively, over the pH range 5.5-6.0. The calibration range for Hg(II) was linear up to 10 ng ml(-1) with a 3 sigma detection limit of 0.02 ng ml(-1); the calibration range for Ag(I) was linear up to 5 mug ml(-1) with a detection Limit of 29 ng ml(-1). The recoveries of the metals were found to be 99.7 +/- 3.8 and 101.3 +/- 4.1% at the 95% confidence level for both Hg(II) and Ag(I). In column operation, it has been observed that Hg(II) and Ag(I) in trace quantities can be selectively separated from geological, medicinal and environmental samples. (C) 2001 Published by Elsevier Science B.V.