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.

In this paper, several fluoride chemical modifiers have been tested for electrothermal vaporization-inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) determination of different volatile elements, such as refractory element Ti, medium volatile element Ni and easy volatile element Pb. Reagents tested include polytetrafluoroethylene (PTFE), NH4F, NaF and CuF2•2H2O. The best overall results are obtained using 6% PTFE added to sample. Under the compromise operating conditions, the detection limits of analytes are in the range of 0.8-59μgml 1 and the calibration curves are linear for over three orders of magnitude. The direct determination of Ti, Ni and Pb in GBW 08505 tea leaves reference sample is shown as an example of PTFE chemical modification.

A sensitive and simple method for low temperature electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) determination of V (Ⅳ) and V (Ⅴ) after separation/preconcentration by a micro-column packed with immobilized thenoyltrifluoroacetone (TTA) on microcrystalline naphthalene has been developed. Thenoyltrifluoroacetone was used as both a chelating agent for micro-column separation/preconcentration and a chemical modifier for ETV-ICP-OES determination of vanadium. Both vanadium species could be trapped by micro-column at pH 4.0, and the vanadate (VO2+) ion could be collected selectively at pH 2.4. Solid material loaded with analyte in the micro-column was dissolved with 100 AL of acetone containing 2.0 mmol L1 TTA and the vanadium was determined subsequently by ETV-ICP-OES. The concentration of vanadyl (VO2+) ion was calculated by subtracting the vanadate concentration from the total concentration of vanadium. Under the optimized experimental conditions, the detection limit (3r) for the preconcentration of 5mL of aqueous solution is 0.068 Ag L1 for both species and the relative standard deviations were 4.3% for vanadium (Ⅴ) and 4.8% for vanadium (Ⅵ) (c=10 Ag L1, n=7), respectively. The method was applied successfully to the determination of vanadium (Ⅳ) and vanadium (Ⅴ) in natural water samples.

A new method of single-drop microextraction combined with low-temperature electrothermal vaporization (LTETV)-ICPMS was proposed for the determination of trace Be, Co, Pd, and Cd with benzoylacetone (BZA) as both extractant and chemical modifier. Several factors that influence the microextraction efficiency, such as sample flow rate, microdrop volume, and extraction time, were investigated and the optimized microextraction conditions were established. Be, Co, Pd, and Cd in the postextraction organic phase were directly determined by LTETV-ICPMS with the use of BZA as chemical modifier. The chemical modification of BZA in LTETV-ICPMS was studied, and the factors affecting the formation of chelates and vaporization/ transportation of chelates were investigated. Under the optimized conditions, the detection limits of the method were 0.12, 0.99, 1.5, and 0.27pg/mL for Be, Co, Pd, and Cd, and the relative standard deviations for 0.1ng/mL Be, Co, Pd, and Cd were 16, 14, 14, and 11%, respectively. After 10min of extraction, the enrichment factors were 160 (Be), 125 (Co), 40 (Pd), and 180 (Cd). The proposed method was applied to the determination of trace Be, Co, Pd, and Cd in biological reference materials, and the determined values were in good greement with the certified values.

A method of glow discharge atomic emission spectroscopy (GD-AES) is described for the determination of rare earth elements (REEs) after separation and preconcentration by micro-column packed with immobilized 1-phenyl-3-methyl-4-benzoyl-5-pyrazone (PMBP) on icrocrystalline naphthalene. The graphite electrode with solution residue on its surface was used as a cathode. Various factors (the form of cathode, working condition) influencing the determination of the analytes were studied in detail. Under the experimental conditions selected, the detection limits for the determination of La, Nd, Eu, Dy and Y are 0.24, 0.32, 0.01, 0.07 and 0.06mg/mL, respectively, with relative standard deviations (RSDs) in the range of 5-10%. The method was applied to determine La, Nd, Eu, Dy and Y in geological samples, and the analytical results are in good agreement with the reference values.