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Abstract  

The five step sequential extraction for speciation of copper and nickel originally designed for sediments has been applied to soil samples. The extractant solutions were: 1 mol/l ammonium acetate, 1 mol/l hydroxylammonium chloride in 25% acetic acid (1∶1), 0.1 mol/l hydrochlorid acid, 0.5 mol/l sodium hydroxide and 8 mol/l nitric acid. The residue was decomposed by HF and HNO3. Using this procedure the metal fraction bound to the organic matter can be distinguished. The concentrations of analytes were determined in the soil extracts by FAAS and ETAAS. Accuracy was assessed by comparing the sum of the contents of copper and nickel in soil extracts with the total certified values of CRMs of soils. The overall recovery values for nickel was 84–105% and for copper 105–114%.

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Abstract  

Performance of commercial Trace Mercury Analyser (TMA) originally devoted to total mercury content analyses in solid and liquid samples was tested in off-line combination with HPLC technique for speciation purposes. RPHPLC system optimized for baseline separation of mercury(II), methylmercury and phenylmercury rendered fractions with volumes directly acceptable by TMA. The main problems of this combination via off-line interfacing i.e. volatility of organomercurials and lost of fractions due to overflow from porous nickel and/or platinum transfer boats were solved by addition of wetting agent (cetyltrimethylammonium bromide) and stabilizing agent (dithizone) into the vessels prior to fractions collection. Calibration curves were measured for Hg(II) and methylmercury within range from 25 ppb to 500 ppb and were linear with correlation coefficients better than 0.9997. Detection limits achieved were around 0.3 ng for both mercury species. No matrix effects were observed during analyses of tap and surface water samples spiked at low ppb levels.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
A. Paulenová
,
P. Rajec
,
M. Žemberyová
,
G. Sasköiová
, and
V. Višacký

Abstract  

The binding of strontium by humic acid was studied in systems designed to model soil leaching conditions. Ultrafiltration experiments were conducted for a wide range of CaCl and NaCl concentrations and for the pH range 4 to 7. It was found that the recovery of humic acid slowly decreased with increasing pH. This occurred because at neutral and basic solutions the increasing degree of ionization of the carboxylate groups leads to the full repulsion state of the humic acid and to increasing of the strontium binding (strontium recovery 60% at pH 7) with this natural polyelectrolyte. The strontium complexation in the presence of calcium was studied in different series of metal concentrations at pH 5 and the ionic strength 0.1M NaCl. The results were explained on the base of the metal ion charge neutralization model of humic complexation (CNM). Loading capacity (cca 40%) and complexation constants and Sr (3.51±0.27) and Ca (3.10±0.29) with Aldrich humic acid were found.

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