| 1. |
- Andersson, Marit, et al.
(författare)
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A modified standard addition method in X-ray fluorescence spectrometry
- 1993
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Ingår i: Talanta. - 0039-9140 .- 1873-3573. ; 40:5, s. 669-674
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Tidskriftsartikel (refereegranskat)abstract
- A modified standard addition method for single element determination by X-ray fluorescence spectrometry has been studied. The attenuation properties of the standard added samples are kept constant by adding decreasing amounts of an attenuation modifier along with increasing amounts of a standard. In this way the standard addition curve will be a straight line in cases where the ordinary standard addition curve is non-linear, and linear regression can be used to evaluate the concentration of the analyte. Standard additions of oxides of a number of elements, with and without modifier, have been made to cellulose powder or a mixture of aluminium oxide and polyethylene as matrices in order to test the method. The method has been applied to the determination of zinc in fly-ash from a steel work and of iron in cement. The fly-ash contained about 5% of zinc and the cement samples between 2 and 5% of Fe(2)O(3). The results were compared with those obtained by ICP-AES after decomposition of samples in lithium tetraborate or lithium metaborate and dissolution of the melt in 10%(v/v) nitric acid. The results agreed within 2%, relative, for fly-ash and within 3-6%, relative, for cement samples.
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| 2. |
- Andersson, Marit, et al.
(författare)
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Determination of bromine, chlorine, sulphur and phosphorus in peat by X-ray fluorescence spectrometry combined with single-element and multi-element standard addition
- 1990
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 37:2, s. 185-191
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Tidskriftsartikel (refereegranskat)abstract
- Bromine (20-40 ppm), chlorine (200-500 ppm), sulphur (0.2-3%) and phosphorus (300-1000 ppm) in peat have been determined by X-ray fluorescence spectrometry (XRFS) combined with the standard-addition method. Chlorine, sulphur and phosphorus have also been determined by other methods and agreement between the results is good. Theoretical calculations based on the Sherman equation were made to validate the linearity of the standard-addition curves. A multi-element standard-addition technique has been tested with addition of all elements at the same time. The results for chlorine were high but after correction for the difference in attenuation coefficient between the sample and added compound the results agreed with those from single-element standard addition.
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| 3. |
- Andersson, Marit, et al.
(författare)
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Determination of lead in household refuse fly-ash by X-ray fluorescence spectrometry and a modified standard-addition technique
- 1991
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Ingår i: Talanta. - 0039-9140 .- 1873-3573. ; 38:4, s. 385-390
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Tidskriftsartikel (refereegranskat)abstract
- Lead in fly-ash from a garbage incinerator has been determined by X-ray fluorescence spectrometry (XRFS) and a modified standard-addition method. To keep the attenuation properties of the spiked samples constant, decreasing amounts of an attenuation modifier [mercury (II) acetate] were added together with increasing amounts of the standard (lead nitrate). Linearity between fluorescence intensity and amount of lead was thus obtained, so the amount of lead in the sample could be evaluated by linear regression. The amount of modifier needed could be calculated from a simple expression. The method was validated by comparison with the results obtained by applying atomic-absorption spectrometry (AAS) to solutions made by leaching the fly-ash with strong acid. For 8 fly-ash samples, containing between 0.8 and 1.35% lead, the largest absolute difference between the two sets of results was 0.03%. Theoretical calculations based on a simplified version of the Sherman equation were performed to confirm the linearity of the modified standard-addition curves.
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| 4. |
- Ericzon, Christina, et al.
(författare)
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Interference from iodide in the determination of trace level selenium
- 1990
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Ingår i: Talanta. - 0039-9140 .- 1873-3573. ; 37:7, s. 725-730
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Tidskriftsartikel (refereegranskat)abstract
- The rate of the reaction between iodide and selenium(IV) at trace levels to form selenium and iodine has been determined in 1–6M hydrochloric acid. The reaction rate increases rapidly with acidity. When hydrochloric acid is added to reduce selenate to selenite prior to the determination of total selenium, some selenium may be lost by reduction to the element if iodide is present. A table of half-lives of the selenite—iodide reaction under various conditions is presented. A method for removal of iodide is suggested.
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| 5. |
- Tóth, I., et al.
(författare)
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Extraction of gallium(III) and aluminium(III) with O,O-dialkyldithiophosphoric acids
- 1990
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 37:12, s. 1175-1178
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Tidskriftsartikel (refereegranskat)abstract
- The extraction of Ga3+ and Al3+ with the liquid cation-exchangers di-n-butyldithiophosphoric acid (DBTPA) and di-(2-ethylhexyl)dithiophosphoric acid (DETPA) in kerosene, in the presence and absence of alcohols and tri-n-butyl phosphate (TBP) has been studied. Both Ga3+ and Al3+ can be extracted in the form of a neutral complex, MA3, but the distribution coefficient of Ga3+ is the higher by about two orders of magnitude, which can be the basis of the solvent extraction separation of gallium and aluminium. The differences can be explained by the interaction between the sulphur donor atoms of the extractants and the d10 electronic shell of Ga3+ as well as by the lower steric hindrance of ligands co-ordinated to Ga3+.
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