Anovel method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace amounts of Pt (Ⅱ), Pd (Ⅱ) and Rh (Ⅲ), based on gaseous compounds introduction into the plasma as their diethyldithiocarbamate complexes by electrothermal vaporization (ETV), was developed. At the temperature of 1100℃, the trace amounts of Pt, Pd and Rh were vaporized into plasma. The factors affecting the formation of the chelates and their vaporization behaviors, such as ashing temperature and time, vaporization temperature and time, pH and the concentration of chelating reagents were studied in detail. Under the optimized conditions, the limits of detection (LODs) (3σ) of Pt, Pd and Rh for tested solutions were 5.4, 1.4 and 0.8μgml−1, and for actual sample (auto-catalyst NIST SRM 2557) were 0.27, 0.07 and 0.04g g−1, respectively. The relative standard deviations (RSDs) for Pt, Pd and Rh were 1.4, 2.6 and 2.4% (CPt=0.5 gml−1, CPd, Rh=0.25 gml−1, n=7), respectively. The linear ranges of calibration graphs for Pt, Pd and Rh cover three orders of magnitude. Compared with conventional electrothermal vaporization technique, using the reagent of diethyldithiocarbamate as chemical modifier could not only enhance the analytical sensitivities, but also reduce the vaporization temperature. By combination with a separation/preconcentration step, the proposed method had been successfully applied to the analysis of the artificial seawater, tap water and urine with recoveries ranging from 91 to 106%. The two certified reference material meager platinpalladium ore GBW 07293 and auto-catalyst NIST SRM 2557 was also analyzed for validation, and the determined values obtained were in good agreement with the certified values.

A simple and selective method of flow injection (FI) using a micro-column packed with chelating resin YPA4 as solid phase extractant was developed for the preconcentration and separation of trace amount of noble metals, Au (Ⅲ), Ag (Ⅰ), Pd (Ⅱ) and Pt (Ⅳ), followed by ICP-AES determination. In HNO3 media, the chelating resin was selective towards Au(Ⅲ), Ag (Ⅰ), Pd (Ⅱ) and Pt (Ⅳ), and the analysed ions were readily desorbed quantitatively with 5ml of 2.5%m/v thiourea. Effects of acidity, sample flow rate and concentration, elution solution and interfering ions on the recovery of the analytes were systematically investigated. Under optimum conditions, the adsorption capacities of YPA4 for Au (Ⅲ), Ag (Ⅰ), Pd (Ⅱ) and Pt (Ⅳ) were 67.2, 43.1, 64.8 and 27.6mg per gram of resin in HNO3 media, respectively. It was found that YPA4 could be used for more than eight runs in HNO3 media without loss of capacity. The proposed method was used for the determination of trace noble metals in geological and environmental samples, and theanalytical results obtained were in good agreement with the recommended values.

A low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) method for the determination of palladium, by using sample introduction of gaseous palladium oxinate, was developed. The thermally stable palladium oxinate was formed and vaporized at a temperature of 900℃ from the graphite furnace. The main factors affecting the vaporization behavior of the analyte were investigated in detail. The detection limit of palladium for this method was 50pg, and the relative standard deviation (RSD) for 0.2μgml-1 palladium was 4.7% (n=8). Compared with conventional ETV-ICPAES, the analytical sensitivity of this method was improved by one order of magnitude. The proposed method was applied to the determination of trace palladium in geological samples with satisfactory results.

A method of electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the determination of trace lanthanides and yttrium in soil samples with a polytetrafluorethylene (PTFE) emulsion as chemical modifier to promote the vaporization of the analytes from the graphite furnace was developed in this paper. The analytical characteristics, spectral interference and matrix effect of the analytical method were evaluated and critically compared with those of pneumatic nebulization inductively coupled plasma mass spectrometry (PN-ICP-MS). Under the optimized operation conditions, the relative detection limits of lanthanides (La-Lu) and yttrium for ETV-ICP-MS and PN-ICP-MS were 0.4-20ngl−1 and 1.0-21ngl−1, respectively, the absolute detection limits for ETV-ICP-MS were 4-200 fg, which were improved by 1-2 orders of magnitude compared with PN-ICP-MS. While the analytical precision of ETV-ICP-MS is worse than that of PN-ICP-MS, with the R. S. D. S (%) of 4.1-10% for the former and 2.9-7.8% for the latter. Regarding to the matrix effect, both conventional method and stepwise dilution method were employed to observe the effect of matrix and the very similar results were obtained. It was found that the highest tolerance concentration of the matrix is 1000mgl−1 and 800mgl−1 for ETV-ICP-MS and PN-ICP-MS, respectively. To assess the accuracy, the proposed method was applied to the determination of trace lanthanides and yttrium in three different soil standard reference materials and one soil sample, and the determined values are in good agreement with the certified values or reference values.

A new method using a micro-column packed with nanometer sized TiO2 as a sorbent has been developed for the on-line preconcentration of trace amounts of rare earth elements (La, Y, Yb, Eu and Dy) prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The effects of pH, sample flow rate and volume, elution solution and interfering ions on the separation of analytes have been investigated. The adsorption capacity of nanometer TiO2 for La, Y, Yb, Eu and Dy was found to be 7.0, 6.1, 9.8, 8.3 and 8.8 mg g21, respectively. The method has been successfully applied for the determination of trace rare earth elements in some environmental samples.