Simple micro-column with multi-walled carbon nanotubes for on-line preconcentration and determination of lead in natural water by hydride generation atomic fluorescence spectrometry

A flow injection on-line preconcentration system was developed for the determination of lead by hydride generation atomic fluorescence spectrometry (HG-AFS). It is based on a simple micro-column filled with multiwalled carbon nanotubes (MWCNTs). The preconcentration of lead on the MWCNTs was carried out based on the adsorptive retention of analyte via on-line introducing the sample into the micro-column system. A 0.3 mol L-1 HNO3 was introduced to elute the retained analyte and merged with KBH4 solution for HG-AFS detection. Under the optimal experimental conditions, an enhancement factor of 26 was obtained with a sample consumption of 14.4 mL. The limit of detection was 2.8 ng L-1 and the precision (RSD) of 11 replicate measurements of 0.2 mu g L-1 Pb was 4.4%. The method was validated by analyzing three certified reference materials, and was successfully applied to the determination of trace lead in natural water samples.