Determination of cadmium in marine waters: on-line preconcentration and flow-through fluorescence detection

This paper reports the development of a new molecular fluorescence spectroscopy method for the determination of cadmium in marine waters. An anthrylhexaazamacrocycle was used as a fluorogenic reagent at pH 13. Ionic extraction chromatography on Dowex resin was necessary to separate cadmium from the matrix and especially from lead, mercury and organic matters present in seawater and interfering with the fluorescence measurements. The coupling of on-line preconcentration by Dowex resin and fluorescence flow-through detection at pH 13 led to a detection limit of 35pM for a preconcentration time of 5min (2.1mlmin-1). The accuracy of the method was verified on certified seawater samples SLEW-2 and NASS-5. Water samples collected in the Scheldt estuary near Antwerp (Belgium) during an ebb tide were analysed for dissolved cadmium