In situ preconcentration of lead by dielectric barrier discharge and its application to high sensitivity surface water analysis

A novel dielectric barrier discharge (DBD) reactor was utilized to in situ enrich and atomize lead in gas phase. The structure of DBD reactor was optimized to broaden the acidity window of plumbane generation from 1% to 3.5%, bringing better analytical stability and practicability deriving from hydride generation process. For the first time DBD proved effective in lead preconcentration and broadening the acidity window of plumbane generation. Pb can be trapped quantitatively (similar to 100%) on the quartz surface of DBD tube under O-2-containing atmosphere and released (similar to 100%) under H-2-containing atmosphere. The absolute detection limit (LOD) for Pb was 4.1 pg (injection volume = 1.2 mL), and the linear (R-2 > 0.999) range was 0.05-100 mu g/L. The results were in good agreement with those of certified reference materials (CRMs), and spiked recoveries for surface water samples were 99-104% with 2-8% RSD. By gas phase analyte enrichment, the proposed method reduced absolute LOD by 10 times. It was deduced that plumbane was changed to lead oxide species trapped on the quartz tube surface and then released, and transported in form of atoms to the detection zone.