Flow-based determination of lead exploiting in-syringe dispersive liquid-liquid micro-extraction in xylene and integrated spectrophotometric detection.

A lab-in-syringe flow system exploiting dispersive liquid-liquid micro-extraction in a solvent lighter than water is proposed for the spectrophotometric determination of lead in industrial residual waters. The steps inherent to both liquid-liquid extraction and monitoring of the formed compound are in-syringe carried out. The classical carbon tetrachloride is not used as the extracting solvent, as it does not present the friendly characteristics inherent to the Green Analytical Chemistry. Aiming at a cleaner alternative for this determination, xylene is selected. Enrichment factor, linear dynamic range, detection limit, sample throughput and residue volume inherent to the proposed procedure were estimated as 36, 50.0-250 μg L-1, 9.0 μg L-1, 13 h-1, and 2.0 mL, respectively.