Flame Atomic Absorption Spectrometric Determination of Gold and Palladium Using Microcolumn On-line Preconcentration and Separation

A microcolumn on-line preconcentration and separation system was developed for the flame atomic absorption spectrometric (FAAS) determination of trace levels of gold and palladium. The analytes were selectively adsorbed onto the microcolumn packed with 2-mercaptothiazole immobilized silica gel (MBTSG) in an acidity range of 0.1 to 6.0 M HCl at a sampling flow rate of 4.0 mL min−1. The analytes adsorbed could be desorbed by a thiourea solution with a flow rate of 2.0 mL min−1. Most of the common coexisting metal ions at a concentration of 25.0 mg mL−1 and anions at a concentration of 50.0 mg mL−1 did not interfere with the preconcentration and determination of Au and Pd. The limits of detection (LOD), defined as three times the standard deviation of the blank (3σ), of Au and Pd are 10 ng mL−1 and 26 ng mL−1, respectively, with a preconcentration time of 60 s. The relative standard deviation (RSD) is about 2.0% for 0.20 µg mL−1 Au and 0.30 µg mL−1 Pd. With a sample loading time of 30 min, 6.7 ng mL−1 Au and 10 ng mL−1 Pd can be preconcentrated quantitatively. A geological sample, an anode slime and a secondary nickel alloy were successfully determined with the proposed method, and the results obtained showed good agreement with the certified values.