Flame atomic absorption determination of lead through on-line preconcentration by surfactant mediated glass wool retention

Abstract

This work reports on the fabrication of a mini column packed with controlled pore glass and glass wool, and its application for the on-line preconcentration of lead with the aid of an anionic surfactant (sodium dodecyl sulphate, SDS) and AAS detection. Lead reacts with SDS in a high-ionic-strength environment, and the product is retained and preconcentrated on a high-surface-area substrate like glass wool. The intervention of controlled pore glass increases the active surface of glasswool and prevents its accumulation into a sticky mass after wetting. Washing the mini column with a methanolic solution of HNO₃, causes the retained micellar face to be eluted, and consequently the lead content can be determined with AAS. A preconcentration factor of 50 along with a signal enhancement due to the combined presence of SDS and methanol yields a detection limit of 1.5 µg L⁻¹. The correlation coefficient of the calibration curve is 0.999, and the linear range 5–500 µg L⁻¹. The method was used for the determination of lead in water and wastewater with good results.

Keywords:

• Controlled pore glass–glass-wool-packed minicolumn
• High-surface-area substrate
• Determination of lead
• On-line surfactant mediated preconcentration
• Atomic absorption spectrometry