Cloud Point Extraction of Palladium as Chelate with 1-(2-pyridylazo)-2-naphthol Using Triton X-114 Prior to Determination in Real Samples by ETAAS

A pre-concentration and determination methodology for palladium in real samples at ultra-trace levels by 1-(2-pyridylazo)-2-naphthol (PAN) was developed. The analyte in the initial aqueous solution, acidified with HCl, was complexed with PAN and Triton X-114 was added as a surfactant. The surfactant-rich phase was diluted with concentrated HNO3 (65%, w/w) after phase separation. Then, the concentrations of analyte were determined by graphite furnace atomic absorption spectrometry (GF-AAS). The variables affecting the complexation and extraction steps were optimized. Under the optimum conditions, namely a pH of 4.5, a cloud point temperature of 55 °C, the concentration of PAN of 1.2×10-4 mol l-1, 0.1% (W/V) Triton X-114, a sample volume of 1.0 ml, (centrifuged at 3500 rpm) an enhancement factor of 26-fold was reached. Triton X-114 allowed the detection limit of 0.01 ng ml?1 of Pd. The precision measured as relative standard deviation (R.S.D.) for 10 replicate determinations at 10.0 ?g l?1 Pd was 2.5%. Analytical graphs were rectilinear in the concentration range of 3-200 ?g l?1 and relative standard deviations were lower than 5%. The method affords recoveries in the range of 97 to 101%. The method was successfully applied for the determination of Pd in dust, drinking water, and rainwater samples.