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

A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with 2-(2-quinolylazo)-5-diethylami- nobenzoic 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 trimethylam- monium 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 en- riched 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 car- tridge with the minimal amount of isopentyl alcohol. The molar absorptivity of the chelate in the isopentyl alcohol medium was 1.43 10 5 Lm ol -1 cm -1 at 628 nm. Beer's law was obeyed in the range of 0.01 - 1.2 g/mL. The relative standard devi- ation for eleven replicate samples at the 0.2 g/L level was 2.18 %. The attained de- tection limit amounted to 0.02 g/L in the original samples. This method was ap- plied to the determination of palladium in environmental samples with good results.