A new method for the determination of free La3+ and La organic complexes in solution using a nanometer-sized titanium dioxide as solid-phase extractant and fluorinationassisted electrothermal vaporization (FETV)-ICP-AES as sensitive detector has been developed. The effect of pH on the adsorption characteristics of La3+ and La complexes of citric acid, 2-hydroxyisobutyric acid (HIBA), and humic acid on nanometer-sized TiO2 was investigated and optimized. On the basis of the difference in volatility between fluoride of analyte (lanthanum) and the fluoride of matrix (titanium), an in-situ removal of the adsorbent matrix (TiO2) from a graphite furnace was realized. Therefore, the free La3+ and adsorbed La complexes on nanometersized titanium dioxide could be determined respectively by FETV-ICP-AES without any other chemical pretreatment. The proposed method was applied for the determination of free ion (La3+) and La complexes in synthetic solutions and soil extracts with satisfactory results.

A sensitive and rapid method for the determination of lanthanum, europium and ytterbium by inductively coupled plasma atomic emission spectrometry (ICP-AES) after solid-liquid extraction with microcrystalline naphthalene was developed. Analytes could be quantitatively adsorbed on tribromoarsenazo-cetylpyridinium bromide-naphthalene (TBA-CPB-naphthalene) packed in a column and determined by ICP-AES after desorption with 3mol l−1 HCl. The effect of various experimental parameters, such as pH, reagent amounts, naphthalene concentrations and diverse ions, on the determination of interesting elements were investigated in detail. Under the optimized experimental conditions, the detection limits of this method for La3+, Eu3+ and Yb3+ were 1.3-8.6ng ml−1, and the relative standard deviations obtained for nine replicate determinations at a concentration of 0.5gml−1 were 1.4-2.2%. The proposed method has been applied in the analysis of NIES CRM No.8 vehicle exhaust particulates and GBW 07602 GSV-1 bush branches and leaves for La, Eu and Yb, and La in NIST SRM 1752 citrus leaves samples; the analytical results were in good agreement with 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.

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.

An in-situ electrothermal fluorination-assisted matrix removal method was developed with PTFE as chemical modifier, and trace-levels of Cr, Co and V in ZrO2 powder were determined. The solid samples were directly introduced into the graphite furnace in the form of a slurry, where the Zr matrix reacted with the active carbon fluoride formed by electrothermal decomposition of PTFE during the pyrolysis stage. Without loss of analytes, the Zr matrix was completely vaporized and removed by the carrier gas. As a result, the matrix interference, which was serious without the modifier, was effectively suppressed, and the chemical attack of the excess of the Zr matrix on the graphite tube was also minimized. The standard additions calibration and the aqueous standard calibration were compared and similar results were obtained. The removal of matrix, the background absorption, the chemical modification of PTFE and the temperature-time program of the graphite furnace were investigated and optimized. The proposed method was applied to the direct determination of trace amounts of Cr, Co and V in ZrO2 powder with aqueous calibration and the results obtained were in good agreement with those obtained by pneumatic nebulization ICP-AES after digestion and separation of the matrix Zr with PMBP extraction. The detection limits of Cr, Co and V were 0.20, 0.32 and 3.7mg g21, respectively.