DIRECT DETERMINATION OF LEAD IN SEA-WATERS BY LASER-EXCITED ATOMIC FLUORESCENCE SPECTROMETRY

This paper describes a laser-excited atomic fluorescence spectrometric method for direct determination of lead in sea-waters down to femtogram levels. No separation/concentration steps nor chemical modifier were used. A programmable, in situ, known addition technique was developed and used as an integral part of the method. The technique reduces sample preparation steps and compensates for spectral line drift better than a standards calibration technique. Four sea-water Certified Reference Materials from the National Research Council of Canada were analysed for Pb concentrations, which were found to be well within certified ranges. Spike recoveries of 100 +/- 10% were achieved using a Certified Reference Material and an unknown sea-water sample. The practical detection limit was 3 fg of Pb absolute (or 1 ng l-1 relative), which, to the authors' knowledge, is the lowest absolute detection limit ever reported for sea-water analysis.