Determination of lead in water by combining precolumn adsorption and fluorimetric detection in a microfluidic device

Abstract

A microfluidic device equipped for in situ fluorescence detection and combined with an off-line microcolumn adsorption is proposed for the determination of lead in natural water. The precolumn adsorption is based on a microcapillary filled with aminopropyl silica. An efficient Pb²⁺ adsorption on aminopropyl silica was proved by Langmuir isotherm adsorption experiments. The maximum adsorption capacity was found to be 5.7 × 10⁻⁴ mol g⁻¹. By using this solid phase extraction procedure (SPE), a 100-fold specific lead concentration was obtained. The concentrated solution was then run into a microfluidic device equipped for fluorescence detection and the complete procedure allows lead determination with a detection limit of 2 μg L⁻¹. Furthermore, it was found that these measurements are not disrupted by the addition of a large excess of other interfering cations.