Solid phase extraction and spectrophotometric determination of palladium with 2-(2-quinolylazo)-5-diethylaminobenzoic acid

摘要

A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with 2-(2-quinolylazo)-5-diethylaminobenzoic acid (QADEAB) and the solid phase extraction of the Pd(II) -QADEAB chelate with a reversed phase polymer-based C18 cartridge was developed. In the presence of 0.05 - 0.5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTAB) medium QADEAB reacts with palladium(II) to form a violet complex with a mole ratio 1:2 (palladium to QADEAB). The chelate was enriched by solid phase extraction with a reversed phase polymer-based C18 cartridge. An enrichment factor of 200 was obtained by elution of the chelate form the cartridge with the minimal amount of isopentyl alcohol. The molar absorptivity of the chelate in the isopentyl alcohol medium was 1.43×105 L mol-1 cm-1 at 628 nm. Beer’s law was obeyed in the range of 0.01-1.2 μg/mL. The relative standard deviation for eleven replicate samples at the 0.2 μg/L level was 2.18 %. The attained detection limit amounted to 0.02 μg/L in the original samples. This method was applied to the determination of palladium in environmental samples with good results.