Spectrofluorimetric detection of zinc and cadmium with 8-(benzenesulfonamido)-quinoline immobilized on a polymeric matrix

Abstract

A chelating resin, 8-(benzenesulfonamido)quinoline immobilized on an XAD-7 support, was prepared and its use for the spectrofluorimetric determination of Zn and Cd was investigated. The immobilized material was placed in a flow cell in a spectrofluorimeter and used in a flow injection system; the fluorescent complex was formed and immobilized in the cell. The chelating resin could be stored for at least three months and used repeatedly without any appreciable amount of reagent being lost. Calibration graphs were linear for up to 500 µg l^–1 of Zn or Cd. Detection limits were 1.6 µg l^–1 for Zn and 1.9 µg l^–1 for Cd. Quantification limits were 5.5 µg l^–1 for Zn and 6.8 µg l^–1 for Cd. Precisions at 50 µg l^–1 were 1.7% for Zn and 1.2% for Cd. Detection limits can be improved by injecting larger volumes of sample. Preconcentration factors of up to 10 were obtained for both metal ions.