DETERMINATION OF LEAD IN METALLIC REFERENCE MATERIALS BY LASER-ABLATION COMBINED WITH LASER-EXCITED ATOMIC FLUORESCENCE

Concentrations of lead in the range 0.15-750 mu g g(-1) were measured in metallic matrices (copper, brass, steel, and zinc) by laser excited atomic fluorescence combined with UV laser ablation in a low-pressure (130 mbar) argon atmosphere. The mass of material ablated was determin ed by repetitive weighing of the target prior to and after approximate ly 10 000 ablating shots. The fluorescence was excited after a 100 mu s delay relative to the ablation pulse. A long integration time of 200 s was used to provide a representative determination of bulk concentr ations. No matrix effect was observed, providing a universal calibrati on curve for all samples with relative standard deviations of about 20 %. The relative and absolute limits of detection were 72 ng g(-1) and 0.5 fg, respectively. (C) 1997 Elsevier Science B.V.