Mo-Hsiung Yang

Comparative determination of Ba, Cu, Fe, Pb and Zn in tea leaves by slurry sampling electrothermal atomic absorption and liquid sampling inductively coupled plasma atomic emission spectrometry

The comparative determination of barium, copper, iron, lead and zinc in tea leaf samples by two atomic spectrometric techniques is reported. At first, slurry sampling electrothermal atomization atomic absorption spectrometry (ETAAS) was applied. The results of Ba and Pb determination were calculated using the method of standard additions, and results of Cu, Fe and Zn from the calibration graphs based on aqueous standards. These results were compared with the results obtained after microwave-assisted wet (nitric+hydrochloric+hydrofluoric acids) digestion in closed vessels followed by inductively coupled plasma-atomic emission spectrometric (ICP-AES) determination with the calibration by means of aqueous standards. The exception was lead determined after a wet digestion procedure by ETAAS. The accuracy of the studied methods was checked by the use of the certified reference material Tea GBW-07605. The recoveries of the analytes varied in the range from 91 to 99% for slurry sampling ETAAS, and from 92.5 to 102% for liquid sampling ICP-AES. The advantages of slurry sampling ETAAS method are simplicity of sample preparation and very good sensitivity. Slurry sampling ETAAS method is relatively fast but if several elements must be determined in one sample, the time of the whole microwave-assisted digestion procedure and ICP-AES determination will be shorter. However, worse detection limits of ICP-AES must also be taken into the consideration in a case of some analytes.

Determination of antimony(III,V) in natural waters by coprecipitation and neutron activation analysis

Abstract A simple and quantitative method for separating antimony(III) from antimony(V) by coprecipitation with thionalide is described. The total concentration of antimony is determined through addition of tin(II) chloride followed by thionalide coprecipitation and antimony(V) is determined by substraction. The coprecipitation system was investigated with the use of 122 Sb radiotracer. The precipitate was collected on a membrane filter for neutron activation analysis. The dectection limit of antimony was found to be in the order of ng l −1 under the experimental conditions. The reliability was checked with National Research Council of Canada standard reference material.

Synthesis, properties and applications of silica-immobilized 8-quinolinol: Part 1. Characterization of silica-immobilized 8-quinolinol synthesized via a Mannich reaction

Abstract A one-step Mannich reaction has been developed for the immobilization of 8-quinolinol on aminopropylsilica gel that results in a product exhibiting a capacity of 466 ± 20 μmol g −1 for copper(II) ions. Capacity measurements were made by copper(II) uptake and elemental analysis. Characterization of the silica bound ligands in this synthetic context including IR spectrometry, 13 C NMR spectrometry, acid-base properties and stabilities were presented. The effect of pH on the extraction of copper(II), nickel(II) and cadmium(II) for silica-immobilized 8-quinolinol was also evaluated.

Synthesis, properties and applications of silica-immobilized 8-quinolinol: Part 2. On-line column preconcentration of copper, nickel and cadmium from sea water and determination by inductively-coupled plasma atomic emission spectrometry

Abstract The coupling of an on-line column preconcentration manifold with continuous flow ultrasonic nebulizer equipped with a desolvation system for simultaneous determination of metal ions by inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The silica-immobilized 8-quinolinol prepared by an improved synthetic route has been evaluated as a preconcentration material for metals in a flow system. Dynamic exchange capacities of this material were ascertained by determining the breakthrough volumes of radiotracer 64 Cu solution under different flow parameters. Optimization of the on-line column preconcentration with ICP-AES measurement was investigated. The feasibility of the proposed method was tested for the determination of Cu, Ni and Cd in open sea water samples. Results obtained for the determination of these elements in NASS-2 sea water sample agreed very well with certified values. The limits of detection based on a sample volume of 25 ml for Cu, Ni and cd were 0.07, 0.054 and 0.016 ng ml −1 , respectively.

The retention behavior of radionuclides on copper(ii)sulfide

Abstract The adsorption properties of copper(II) sulfide in various acid solutions for different radiotracers are described. Column and batch equilibration methods are discussed. Copper(II) is selectively adsorbed on CuS; the decontamination factor exceeds 10 6 for column operations in 6 M hydrochloric acid solution. Among the 30 ions tested in 6 M hydrochloric acid, only copper and gold are adsorbed quantitatively; mercury, silver, bromine, technetium and molybdenum are adsorbed partially. The retention capacity for copper(II) is around 20 mg Cu/g CuS. The adsorption processes on CuS as functions of acid concentrations (HCl, HClO 4 and H 2 SO 4 ) are described. The method seems applicable in activation analysis for trace elements in copper matrices.

SIMULTANEOUS DETERMINATION OF ARSENIC, MERCURY, ANTIMONY AND SELENIUM IN BIOLOGICAL MATERIALS WITH PRIOR COLLECTION OF GASEOUS PRODUCTS FOLLOWED BY NEUTRON ACTIVATION ANALYSIS

A method combining prior collection of gaseous products with subsequent neutron activation analysis has been developed for simultaneous determination of traces of arsenic, mercury, antimony and selenium in biological materials. The generation of hydrides of arsenic, antimony and selenium and cold vapor of mercury in the vapor generaion and collection system was investigated by the use of radiotracers of the respective elements. The result indicates that selenium and mercury can be completely evaporated from the digested sample solution in 5M HCl with the addition of 5% sodium tetrahydroborate solution, while additional reduction proces by potassium iodide and ascorbic acid is needed for complete evaporation of arsenic and antimony. The gaseous products were collected in a quartz tube for neutron irradiation. The detection limits of these elements were fount to be in the range of 10−7 to 10−8 g under the present experimental conditions. The reliability was checked with NBS standard reference materials.

Determination of trace elements by neutron activation analysis using dinonylnaphthalene sulfonic acid as a preconcentrating agent

Dinonylnaphthalene sulfonic acid (HD) has been used as a preconcentrating agent to enrich trace metal ions and to separate the interfering elements such as Na, K, Cl and Br which normally exist in the natural aqueous systems. Experiments were performed by extracting the ions in the aqueous medium with HD in n-hexane and subsequently back-extracted into a minimal volume of acid solution. Factors influencing the extraction efficiency of the ions of interest were investigated. The preconcentration technique developed in this study was applied to the determination of trace elements in biological and natural water samples by neutron activation analysis.

On the determination of phosphorus depth profile in phosphorus-doped silicon

The depth profile of phosphorus concentration in phosphorus-doped silicon was shown to be measureable with an accuracy of 1–3% by the use of liquid scintillation counting after neutron irradiation. Both the amount of Si and P are determined by neutron activation analysis followed by liquid scintillation counting for 1–5 hours after the end of irradiation and 5–10 days after irradiation, respectively. Concentrations as low as 10 ppm and thicknesses of 20 nm can be determined.

Neutron activation analysis for heavy metals in caustic soda

Abstract A neutron activation method has been developed for the simultaneous determination of eight heavy metals in caustic soda. The heavy metals are pre-concentrated by complexing with cyanide and anion exchange. A further removal of 24 Na by HAP is applied after irradiation, and the γ-rays from the nuclides of interest are assayed with a Ge(Li) detector.