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G Rauret

Publications and source records attributed to G Rauret.

28 records · Page 2Linked to original sources
PubMed2000

Application of a modified BCR sequential extraction (three-step) procedure for the determination of extractable trace metal contents in a sewage sludge amended soil reference material (CRM 483), complemented by a three-year stability study of acetic acid and EDTA extractable metal content.

This paper provides additional data on a sewage sludge amended soil certified reference material, CRM 483, which was certified in 1997 for its EDTA and acetic acid extractable contents of some trace metals, following standardised extraction procedures. The additional work aimed to test the long-term stability of the material and the applicability of an improved version of the BCR three-step sequential extraction procedure on the sewage sludge amended soil (CRM 483). The paper demonstrates the CRM 483 long-term stability for EDTA and acetic acid extractable contents of Cd, Cr, Cu, Ni, Pb and Zn and gives the results (obtained in the framework of an interlaboratory study) for the extractable contents of the same elements in the CRM 483, following the BCR three-step sequential extraction scheme. The aqua regia extractable contents following the ISO 11466 Standard are also given. The data are given as indicative (not certified) values.

Acetic Acid↗
PubMed1999

Prediction of the impact of the Aznalcóllar toxic spill on the trace element contamination of agricultural soils.

The interaction of several trace elements (Cd, Zn, Cu, Pb, As, Bi, and Tl) was studied by leaching experiments in agricultural soils affected by the Aznalcóllar toxic spill. The spill led to contamination by acid waste waters and sludge deposition. The levels of contamination recorded after the sludge was removed from soils showed that highly contaminated areas remained. A comparison of soils directly affected by sludge deposition and acid waste waters with soils contaminated only by acid waste waters demonstrated that Zn/As and Cd/As ratios were good indicators of the two contributions to the contamination. Soil samples were characterised and grouped according to their texture and carbonate content. The response of elements to single extractions with CaCl2 0.01 mol l-1, CaCl2 1 mol l-1, CH3COOH 0.43 mol l-1, and EDTA 0.05 mol l-1 enabled us to estimate their mobility in the soils. Cd and Zn were found to be the most mobile elements. Cu showed an intermediate mobility, especially in an acidic medium. Pb, As, Bi and Tl were found to be non-mobile elements. A comparison of referent, low and highly contaminated samples showed that the presence of sludge had an effect on desorption yields, in part due to the short-term after the contamination. Calculations of a relative scale of long-term mobility, between soils and trace elements, provided further conclusions derived from the use of single extractions.

Accidents, Occupational↗
PubMed1999

Selection and evaluation of sequential extraction procedures for the determination of phosphorus forms in lake sediment.

In order to achieve comparable measurements in the determination of phosphate forms in freshwater sediments, the Standards, Measurements and Testing Programme (formerly BCR) of the European Commission has launched a project the first step of which was to select and evaluate collaboratively existing extraction procedures. This was carried out through expert consultations and a literature survey, and was followed by the organisation of a first interlaboratory study for the evaluation of four sequential extraction schemes, one of which was selected as the most promising method for achieving comparability. This scheme, a modified version of the Williams protocol, was further tested in a second interlaboratory study. The so-called SMT extraction scheme seems promising and will provide, in the near future, a valuable tool for water managers in the field of lake restoration. It will be particularly helpful in estimating the stock of P potentially available, hence the risk of eutrophication due to internal P release.

Chemistry Techniques, Analytical↗
PubMed1999

Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials.

The Standards, Measurements and Testing Programme (formerly BCR) of the European Commission proposed a three-step sequential extraction procedure for sediment analysis, following extensive expert consultations and two interlaboratory studies. This scheme was recently used to certify the extractable trace element contents of a sediment reference material (CRM 601). Although this procedure offers a means to ensure the comparability of data in this field, some difficulties concerning the interlaboratory reproducibility still remain, and a new project is currently being conducted to determine the causes of poor reproducibility in the extraction scheme. The final objective of the project is the certification of new sediment and soil reference materials for their extractable contents of Cd, Cr, Cu, Ni, Pb and Zn. This paper presents the results of a small-scale interlaboratory study, which aimed to test a revised version of the extraction schemes by comparing the original and the modified protocols using the CRM 601 sample. This work offers an improvement to the BCR sequential extraction procedure through intercomparison exercises. This improved procedure will allow the obtaining of CRMs to validate analytical data in the analysis of soils and sediments, and it will also facilitate comparability of data in the European Union.

Calibration↗
PubMed1990

Nitriles and isonitriles as interferents in cyanide determination in polluted waters.

The interference of nitriles and isonitriles in cyanide determination was studied using the pyridine-barbituric acid direct spectrophotometric method or the same method after distillation of the sample, a microdiffusion-potentiometric (ion-selective electrode) also being used. Phenylacetonitrile, benzonitrile, acrylonitrile, iminodiacetonitrile and acetonitrile were tested as nitriles. Benzyl isocyanide butyl isocyanide and 1-[(isocyanomethyl)sulphonyl]-4-methylbenzene were assayed as isonitriles. It can be concluded that both nitriles and isonitriles should be considered as interferents in all the methods of cyanide determination studied. The level of interference generally increases with the ratio of interfering compound to cyanide and is greatest for low cyanide concentrations.

Cyanides↗
PubMed1985

Application of the combustion method in a closed flask to the lead determination in atmospheric aerosols.

The destruction of the filter for metal determination in atmospheric aerosols is an important step in the analysis. Nowadays the decomposition of this kind of sample has not been completely solved, so it is interesting to study new methods for filter sample attack. In the present work the application of the combustion method in a closed flask for mixed cellulose esters filter decomposition for lead determination is proposed. For this purpose optimum operating conditions as stopper flask design, sample size, flask volume, shaking time and volume and concentration of absorbing solution are established, and accuracy and precision of the proposed method using AAS for the measurements is given. The results obtained by the closed flask combustion are compared with those found by wet attack with HNO3. The method proposed is rapid, has low reagent contamination and no loss of lead by volatilization or by amalgamation occurs. This method shows an accuracy and a precision in good agreement with the standard method.

Air Pollutants, Occupational↗
PubMedDate not supplied

Reusability of plastic scintillators used in beta emitter activity determination.

The use of plastic scintillation in the measurement of beta emitter activity is a suitable alternative to classical detection techniques in spite of the high cost and potential memory effects. Reuse of the plastic scintillator beads after a cleanup procedure would overcome both drawbacks. In the present paper, we tested several cleaning solutions (water, HCl 0.1M, commercial soap, EDTA 0.01 M pH=3, citric acid 0.1 M pH=3). The recommended procedure consists of the immersion of the beads in three consecutive citric acid baths for 24 h. If this protocol is followed, plastic beads contaminated with 90Sr/90Y, 14C, and 3H recover their initial condition, and can be used in successive determinations.

Beta Particles↗
PubMedDate not supplied

Prediction of trace element mobility in contaminated soils by sequential extraction.

The modified three-step sequential extraction procedure proposed by the Community Bureau of Reference (or Bureau Communautaire de Reference, BCR) was used to predict trace element mobility in soils affected by an accidental spill comprising arsenopyrite- and heavy metal-enriched sludge particles and acid waste waters. The procedure was used to obtain the distribution of both the major (Al, Ca, Fe, Mg, and Mn) and trace elements (As, Bi, Cd, Cu, Pb, Tl, and Zn) in 13 soils of contrasting properties with various levels of contamination and in the sludge itself. The distributions of the major elements enabled us to confirm the main soil fractions solubilized in each of the three steps, and, in turn, to detect the presence of pyritic sludge particles by the high Fe extractability obtained in the third step. Cadmium was identified as being the most mobile of the elements, having the highest extractability in the first step, followed by Zn and Cu, Lead, Tl, Bi, and As were shown to be poorly mobile or nonmobile. In the case of some of the trace elements, the residual fractions decreased at higher levels of contamination, which was attributed to the anthropogenic contributions to the polluted samples. Comparison with soil-plant transfer factors, calculated in plants growing in the affected area, indicated that a relative sequence of trace element mobility was well predicted from data of the first step.

Accidents↗
PubMedDate not supplied

Liquid chromatographic determination of available lysine in soybean and fish meal.

A method for the determination of available lysine on the basis of the reactivity of the epsilon-amino group with fluorodinitrobenzene (FDNB) has been optimized. Hydrolysis is performed in closed vessels in an autoclave. Conditions for different meals were established by using a modified sequential simplex method. Hydrolysis for 4 h was sufficient for the meals studied--soybean and fish. The use of liquid chromatography to determine available lysine was studied, and optimum conditions were established for separation and quantitation of epsilon-DNB-lysine. The proposed method is faster, more accurate, and more precise than commonly used methods.

Animals↗