Novel Technique for Ultra-Trace Determination of Lead in Seawater Samples Using Gold Coated Tungsten Coil Atom Trap Hydride Generation Atomic Absorption Spectrometry

A novel and simple trap technique combining a gold-coated tungsten coil with hydride generation atomic absorption spectrometry (HGAAS) were developed for ultra-trace lead determination. The technique was based on first transporting the plumbane produced by the HG system, together with H-2, to a trap externally heated to 92 degrees C, where it was collected for in-situ preconcentration and then volatilized by raising the trap temperature to 510 degrees C. For a 120 s trapping time, the limit of detection (LOD) was 2.9 ng L-1, the limit of quantification (LOQ) was 9.7 ng L-1 and the relative standard deviation was 3.1 % (at 0.02 mu g L-1). The analytical performance of the technique was contrasted against the classical HGAAS method and a 39.2-fold increase in sensitivity was obtained when comparing the characteristic concentrations of both methodologies. The morphology of the trap surface was also studied using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The accuracy of the proposed method was verified by analyzing the Pb concentration in the certified reference materials and the results agreed well with the certified values. Finally, the developed procedure was successfully applied to seawater samples and the recoveries of standard addition were between 102.4 % and 105.2 %.