Flow through luminescence for heavy metal analysis in seawater

Abstract

The toxicity of heavy metals is well documented today and legislation for their control in seawater continuously becomes more and more restrictive. In order to control and ensure the marine environment quality it is demanded an effort to develop new analytical tools, which allow the analysis of trace levels of heavy metals in seawater. The measurement of luminescence (phosphorescence and fluorescence) gives rise to high sensitive, selective and innovative approaches which could be used to develop new trace metal sensing methods. In this way, we have observed that the metal-chelates formed between different sulphonic-hydroxyquinolines with heavy metals, such as lead, or the metal-chelates between mercury and purines exhibit strong room temperature phosphorescence and fluorescence, respectively. Based on the formation of such quelates, two luminescence methods are investigated for sensing of lead and mercury in seawater. Optimum experimental conditions and the analytical performance characteristics of the methods are discussed. Relative standard deviations in the order of 4% are typical at 100 ng mL<SUP>-1</SUP> of Pb(II) and Hg (II). The detection limits are 0.1 and 1.4 ng mL<SUP>-1</SUP> for lead and mercury, respectively. Possible interferences present in seawater, including sea water cations and anions are evaluated in detail. Finally, the methods are applied to the determination de mercury and lead in seawater samples.