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“Internal standard activation analysis of silicon in steel”. van Grieken R, Gijbels R, Speecke A, Hoste J, Analytica chimica acta 43, 381 (1968). http://doi.org/10.1016/S0003-2670(00)89235-1
Abstract: Non-destructive 14-MeV neutron activation analysis for silicon in steel has been applied with 56Mn as internal standard.56Mn is formed from the iron matrix via the 56Fe(n,p)56Mn reaction. Several methods of internal standardisation via56Mn are discussed. The 0.84-MeV photopeak of 56Mn is recommended if steel samples of about the same composition are to be analysed. Chemically analysed steel samples are used as silicon standards. A precision of 0.7% was obtained for an analysis plus standardisation time of 13 min. Special attention was paid to interferences produced by concentration changes of impurity elements. Several possible sources of errors were investigated.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.513
Times cited: 14
DOI: 10.1016/S0003-2670(00)89235-1
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“The determination of copper in iron and steel by 14-Mev neutron activation analysis”. Van Grieken R, Speecke A, Hoste J, Analytica chimica acta 51, 151 (1970). http://doi.org/10.1016/S0003-2670(01)95703-4
Abstract: A fast (10 min) non-destructive determination of copper in. steel and cast iron by 14-MeV neutron activation analysis is described. The 0.511-MeV annihilation radiation of62Cu (T1/2=9.8 min), induced by the reaction63Cu(n,2n)62Cu, is counted by two opposing NaI(Tl) detectors operating in coincidence. An oxygen flux monitor is used to normalise the irradiations. For high phosphorus contents, two measurements are made and the 9-min activity contribution is calculated. As the iron content of the samples is known, the use of pure iron samples allows correction for53Fe activity from the reaction54Fe(n,2n)53Fe(T1/2= 8.9 min). When the phosphorus and silicon activities are low, the procedure of counting and computing can be greatly simplified. Nuclear interferences of most common alloying and impurity elements were investigated.The precision is 23% for steels containing above 1% Cu, andCa. 10% for 0.1%Cu.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)95703-4
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“Determination of silicon in natural and pollution aerosols by 14-MeV neutron activation analysis”. Gijbels R, Dams R, Analytica chimica acta 63, 369 (1973). http://doi.org/10.1016/S0003-2670(01)82362-X
Abstract: The determination of silicon via the 28Si(n,p)28 Al reaction by means of 14-MeV neutrons is applied to the analysis of pollution and natural aerosols. A Whatman 41 filter (40 cm2) on which airborne particulate material has been collected is compressed into a 3 × 12.7 mm pellet. Standards are prepared in the same way from clean filters spiked with a silicate solution. After a 50-s irradiation and a 75-s decay time, the sample is counted for 2 min with 5 × 5 NaI(Tl) well detector. The 1.779-MeV photopeak of 28Al is measured with a single channel sealer chain or with a multichannel analyser. The reproducibility, sensitivity and liability to interference from other elements were investigated for both counting systems. The homogeneity of the pellets and the filters was checked. The overall precision of one single-channel determination was estimated to be 3.5% after a 24-h high-volume sampling time. Samples collected in urban, industrial and remote areas with concentrations ranging from 0.05 to 15 μg Si m-3 air were analysed and the results are discussed.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.513
Times cited: 16
DOI: 10.1016/S0003-2670(01)82362-X
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“Systematic errors in 14-MeV neutron activation analysis for oxygen : part 1 : neutron and γ-ray attenuation effects”. Vandecasteele C, van Grieken R, Gijbels R, Speecke A, Analytica chimica acta 64, 187 (1973). http://doi.org/10.1016/S0003-2670(01)82436-3
Abstract: A detailed account is given of neutron and γ-ray attenuation effects in 14-MeV neutron activation analysis of oxygen. Appropriate neutron cross-section values have been determined in two different ways and compared with literature values. It appears that the attenuation process is best described in terms of nonelastic scattering cross-sections. It is also shown that the narrow beam total γ-ray attenuation coefficients at 6 MeV, given in the literature are suitable for correction purposes if 16N γ-rays are counted with a window of 4.56.5 MeV. Attention was paid to the contribution of β-rays when the 16N activity is counted in this energy interval with a NaI(Tl) detector.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.513
Times cited: 11
DOI: 10.1016/S0003-2670(01)82436-3
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“Systematic errors in 14-MeV neutron activation analysis for oxygen : part 2 : a general standardization method for the determination of oxygen”. Vandecasteele C, van Grieken R, Gijbels R, Speecke A, Analytica chimica acta 65, 1 (1973). http://doi.org/10.1016/S0003-2670(01)80158-6
Abstract: A general standardization method is described for the determination of oxygen in solid samples via the 16O(n,p)16N reaction. Two systems of flux monitoring are considered: the sample versus standard comparator method and BF3 monitoring. The average flux in sample and standard, fast neutron shielding, fast neutron scattering, absorption of fast neutrons, absorption of 16N γ-rays and counting efficiency of sample and standard are considered. The influence of the target diameter on the obtained correction factors has also been studied. Total achievable accuracy is believed to be about 1%.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.513
Times cited: 12
DOI: 10.1016/S0003-2670(01)80158-6
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“Elemental analysis of aerosol-size fractions by proton-induced X-ray-emission”. Johansson TB, Nelson JW, Van Grieken RE, Winchester JW, Transactions of the American Nuclear Society 17, 103 (1973)
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Elemental analysis of aerosols using proton-scattering”. Nelson JW, Williams I, Johansson TB, Van Grieken RE, IEEE transactions on nuclear science Ns21, 618 (1974). http://doi.org/10.1109/TNS.1974.4327522
Abstract: Elemental analysis for all of the light elements up through chlorine by elastic scattering of 16 MeV protons has been shown to be feasible. Basic problems associated with such measurements are discussed including kinematics, angular distribution, and sample backings. Spectra are presented for air particulate matter for both a total filter (Nuclepore) and a size fractionated air impactor (polystyrene backed) sample. The method is absolute, non destructive and can be used in conjunction with proton induced x-ray fluorescence to quantitatively analyze all elements in the same sample in minutes of time.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1109/TNS.1974.4327522
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“Simultaneous determination of chromium and silicon in steel by 14-mev neutron activation analysis”. Vandecasteele C, Van Grieken R, Hoste J, Analytica chimica acta 72, 31 (1974). http://doi.org/10.1016/S0003-2670(01)82945-7
Abstract: Chromium and silicon are determined simultaneously in steel by 14-MeV neutron activation analysis. The activities of 52V(Eγ=1.43 MeV,TView the MathML source=3.76 min) from 52Cr(n,p)52V and 28Al (Eγ=1.78 MeV; TView the MathML source=2.24 min) from 28Si(n,p)28Al are evaluated by mixed γ-ray spectrometry. The influence of manganese and phosphorus, the main interfering elements, is negligible for most stainless steels. The count rate should be limited, to avoid 52V pulse pile-up effects interfering in the 28Al energy region. Precisions in the 2-10% range are reached, depending on the concentrations, for a 10-min analysis time. Results for a series of steel samples are compared with industrial analyses.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)82945-7
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“Elemental trace analysis of small samples by proton-induced X-ray-emission”. Johansson TB, Van Grieken RE, Nelson JW, Winchester JW, Analytical chemistry 47, 855 (1975). http://doi.org/10.1021/AC60356A035
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC60356A035
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“Absorption correction for X-ray-fluorescence analysis of aerosol loaded filters”. Adams FC, Van Grieken RE, Analytical chemistry 47, 1767 (1975). http://doi.org/10.1021/AC60361A040
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC60361A040
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“Elemental abundance variation with particle-size in north florida aerosols”. Johansson TB, Van Grieken RE, Winchester JW, Journal of geophysical research 81, 1039 (1976). http://doi.org/10.1029/JC081I006P01039
Abstract: A nonurban base line has been established for nine trace element constituents of aerosol particles as a function of particle size at ground level sampling stations in north Florida up to 50 km from the Gulf of Mexico. The particle size range 0.25- to >4-μm aerodynamic diameter was investigated by cascade impactor sampling and elemental analysis by proton-induced X ray emission. By using a strategy of sampling at urban, forest, and coastal locations and by choosing approximately 48-hour sample averaging intervals the potential dependence of the base line levels both on local pollution and natural sources and on local particle size specific aerosol removal processes could be evaluated. It is found that elements contained in the largest particles, especially those of >4 μm, display the greatest degree of average concentration difference between sites, a result suggesting short atmospheric residence times and the importance of local dispersion sources and atmospheric cleansing processes in regulating the particle concentrations in air. Elements contained in particles of <2-μm diameter show little average concentration difference between sites unless they are influenced by local pollution sources, a finding suggesting that their concentrations in air are regulated by large-scale sources and transport processes. Sulfur in the smallest particles shows a marked constancy of concentration, but it may be modified in the largest particle size ranges in relation to proximity to the seacoast. No evidence is found for dependence of particulate sulfur concentrations on local pollution sources. K, Ca, Ti, Fe, and Zn appear to be regulated in the main by terrestrial source processes, and Cl by marine source processes, but Br and Pb appear to be accounted for adequately by assuming automotive fuel combustion as their major source. Limited data obtained for V indicate that it may vary considerably with fluctuations in aerosol transport from oil-fired electric power plant sources in the region. Limited additional data also suggest that Mn is derived from sources of natural terrestrial composition. In view of these findings, certain criteria may be set for the design of a meaningful nonurban aerosol monitoring network.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1029/JC081I006P01039
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“Folding of aerosol loaded filters during X-ray fluorescence analysis”. Van Grieken RE, Adams FC, X-ray spectrometry 5, 61 (1976). http://doi.org/10.1002/XRS.1300050204
Abstract: Folding aerosol loaded filters in two with the loaded side inwards during the X-ray analysis not only reduces possible filter heterogeneity effects and improves sample protection, but also increases the sensitivity and renders filter paper absorption corrections simple and more accurate in many instances. It is shown that folding an aerosol loaded Whatman filter paper during Kα X-rays counting leads to an increased sensitivity for all elements up from calcium, scandium or titanium (depending on the sensitivity definition and on the aerosol load) and for all elements up from phosphorus, sulphur or chlorine in the case of the Nuclepore filter. Although the absorption by the filter, into which the aerosol penetrates to some extent, is always more important in the sandwich than in the usual geometry, the dependence of the absorption correction on the usually unknown average deposition depth is less pronounced. Assuming all the aerosol material to be collected at the very surface of the filter and hence being present in the centre of the sandwich to be analysed, leads to an extremely simple filter paper absorption correction which is less prone to uncertainties than more sophisticated corrections in the usual geometry requiring additional measurements. This is the case for all elements up from potassium on Whatman filters and up from phosphorus on Nuclepore filters.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300050204
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“Geophysical applicability of aerosol size distribution measurements using cascade impactors and proton-induced X-ray-emission”. Van Grieken RE, Johansson TB, Akselsson KR, Winchester JW, Nelson JW, Chapman KR, Atmospheric environment : an international journal 10, 571 (1976). http://doi.org/10.1016/0004-6981(76)90040-8
Abstract: Proton Induced X-ray Emission, (PIXE), is capable of high precision analysis for trace element components of aerosol particle size fractions sampled by cascade impactor. A statistical evaluation of data quality has been carried out in order to distinguish between analytical uncertainties in the PIXE procedure, errors caused by cascade impactor performance and by other factors in the sampling procedure, and geophysical causes of differences in composition and particle size distributions of the elements in aerosols. Replicate analyses and simultaneous samplings taken in north Florida and St. Louis have been used for the data evaluation. In addition to the analytical error the sampling procedure contributes an error of ~ 10% to be added quadratically. The resulting precision is sufficient to evaluate the data in geophysical terms. This is illustrated by means of sample sets taken simultaneously in an urban, forest and coastal environment of the same region.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0004-6981(76)90040-8
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“Optimization of a simple spotting procedure for x-ray fluorescence analysis of waters”. Smits J, Van Grieken R, Analytica chimica acta 88, 97 (1977). http://doi.org/10.1016/S0003-2670(01)96053-2
Abstract: Several sample preparation methods for waters for energy-dispersive x.r.f. were examined, as well as the influence of sample size on the analytical characteristics. The most satisfactory simple, rapid method proved to be spotting of 1.5 ml of water sample on a Whatman-41 cellulose filter paper provided with a wax ring of 29-mm diameter and evaporating the water with an unheated air stream from underneath. Sensitivities are below 100 p.p.b. for most elements and often below 50 p.p.b. when the optimal secondary fluorescer is used. Accuracy and precision are usually in the 1520 % range. The method is applicable to many dilute aqueous solutions as is illustrated by analysis of industrial water samples and ashed biological material.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)96053-2
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“Reduction of trace metal levels in analytical-grade activated carbon”. Vanderborght B, Van Grieken R, Analytica chimica acta 89, 399 (1977). http://doi.org/10.1016/S0003-2670(01)84739-5
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)84739-5
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“Chelex-100 ion-exchange filter membranes for preconcentration in x-ray-fluorescence analysis of water”. Van Grieken RE, Bresseleers CM, Vanderborght BM, Analytical chemistry 49, 1326 (1977). http://doi.org/10.1021/AC50017A011
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC50017A011
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“Analysis of X-ray spectra excited by X rays, electrons, and protons in monazite”. Annegarn HJ, Madiba CCP, Sellschop JPF, Genz H, Hoffmann DHH, Low W, Richter A, Van Grieken RE, Physical review : C : nuclear physics 16, 379 (1977). http://doi.org/10.1103/PHYSREVC.16.379
Abstract: Mineral monazite from Malaysia has been investigated by energy dispersive x-ray analysis employing three different methods: x-ray, relativistic electron and proton induced excitation. An upper limit of 15 ppm has been placed on the possible concentration of the superheavy element with Z=126.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1103/PHYSREVC.16.379
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“Determination of protein-bound copper and zinc in some organs of the cuttlefish Sepia officinalis L”. Decleir W, Vlaeminck A, Geladi P, Van Grieken R, Comparative biochemistry and physiology : B : biochemistry and molecular biology 60, 347 (1978). http://doi.org/10.1016/0305-0491(78)90057-3
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0305-0491(78)90057-3
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“Trace metal analysis of water containing humic substances by X-ray fluorescence”. Vanderborght BM, Van Grieken RE, International journal of environmental analytical chemistry 5, 221 (1978). http://doi.org/10.1080/03067317808071147
Abstract: Chelation by oxine followed by adsorption on activated carbon results in the efficient collection of many trace metal ions, independent of the trace metal concentration and of high alkali and alkaline earth ion abundances. Preconcentration factors around 10000 are often achieved. When this preconcentration procedure is combined with energy-dispersive X-ray fluorescence, accurate and precise analysis can be carried out, as was proven in several experiments. The technique can also be applied for the determination of divalent ions in natural waters containing up to 10 ppm of humic substances. Trivalent ions can quantitatively be collected from natural water provided suKicient activated carbon is added. Omitting the oxine chelation prior to the activated carbon adsorption step still results in collection of a sometimes important fraction of the trace metal ions from natural waters. This is related to organically bound or colloidal forms of the trace metals.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1080/03067317808071147
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“Automated evaluation of photographically recorded spark-source mass spectra”. Vanderborght B, Van Grieken R, Analytica chimica acta 103, 223 (1978). http://doi.org/10.1016/S0003-2670(01)84041-1
Abstract: A computer routine was developed for qualitative and quantitative analysis of photographically recorded spark-source mass spectra. Particular attention is given to the case of a graphite matrix. The program starts from the line intensities (expressed as Seidel values) and isotope masses calculated from the densitometer readings by a commercially available routine. From the intensities in the different exposures (typically 15 stages), it computes the parameters for the linear parts of the density curves for each ion. Taking into account mutual interferences of multivalent ions, isotope or C-clusters, oxide, carbide and dicarbide ions, the program automatically identifies and then quantifies the elements present. The precision of the results is around 5%. Reading and complete processing of one photoplate is achieved within 23 h.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)84041-1
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“Co-crystallization with 1-(2-pyridylazo)-2-naphthol, and X-ray fluorescence, for trace metal analysis of water”. Vanderstappen MG, Van Grieken RE, Talanta : the international journal of pure and applied analytical chemistry 25, 653 (1978). http://doi.org/10.1016/0039-9140(78)80166-0
Abstract: Adding 20mg of 1-(2-pyridylazo)-2-naphthol (PAN) to a water sample at 70°, and filtering off the precipitate after cooling, gives efficient preconcentration prior to X-ray fluorescence analysis of water. Up to the capacity of about 100 μeq of PAN used, the trace metal recoveries are around 90% or higher for Cr3+, Mn2+, Ni2+, Cu2+, Zn2+, Hg2+ and Eu3+, and above 70% for many other ions. The recovery yields usually do not vary critically with pH in the neutral pH-range, and are practically independent of the sample salinity, sample volume and trace-metal concentration. Enrichment factors as high as 2 × 105 can be achieved. Counting statistics would then allow detection limits of 0.03 ppM. The blank levels in commercial PAN, however, lead to typical detection limits of about 1 ppm. The coefficient of variation is typically in the 510% range at the 10-ppM level. The accuracy and applicability of the procedure are illustrated by comparative analyses on samples of synthetic solutions, river and drinking water.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0039-9140(78)80166-0
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“Effective sample weight from scatter peaks in energy-dispersive x-ray fluorescence”. van Espen P, Van 't dack L, Adams F, Van Grieken R, Analytical chemistry 51, 961 (1979). http://doi.org/10.1021/AC50043A042
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1021/AC50043A042
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“Spark-source mass-spectrometric sensitivity factors for elements in a graphite matrix”. Vanderborght B, Van Grieken R, Talanta : the international journal of pure and applied analytical chemistry 26, 461 (1979). http://doi.org/10.1016/0039-9140(79)80111-3
Abstract: Relative sensitivity factors for determination of 41 elements by spark-source mass-spectrometry have been measured. The samples were pressed into graphite electrodes and ionized with a radiofrequency spark. The mass spectra were recorded on a photoplate and the resulting data processed by a computer. Indium was used as standard and the relative sensitivity factors for both singly- and doubly-charged ions were determined with reference to the singly-charged indium ion, with an overall error of 30%. The mean analysis precision was 16%.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0039-9140(79)80111-3
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“Soil analysis by thin-film energy-dispersive X-ray fluorescence”. Van Grieken R, Van 't dack L, Costa Dantas C, Da Silveira Dantas H, Analytica chimica acta 108, 93 (1979). http://doi.org/10.1016/S0003-2670(01)93044-2
Abstract: Energy-dispersive x-ray fluorescence is advantageous for trace analysis of soils present as thin films. A target thickness of about 2 mg cm-2 provides a compromise between optimal sensitivity and minimal absorption effect or optimal accuracy. Sample preparation involves only suspending the finely ground soil in water and drying this suspension on a thin mylar foil glued on a ring that fits into the x.r.f. spectrometer. The effective sample weight present in the exciting beam area is computed from the scatter peaks, a method that cancels out target heterogeneity problems. High accuracy is demonstrated for many elements in reference soil and rock materials; a precision around 5% and a detection limit around 10 ppm can be achieved. As an illustration, results for 16 trace elements and preliminary interpretation are given for a series of pedologically important soil samples from Brasil.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)93044-2
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“Comparison of preconcentration procedures for trace metals in natural waters”. Smits J, Nelissen J, Van Grieken R, Analytica chimica acta 111, 215 (1979). http://doi.org/10.1016/S0003-2670(01)93264-7
Abstract: The relative merits of eight procedures for preconcentrations of trace metal ions from natural water samples and synthetic solutions are evaluated. Spikes (100 μg l−1 ) of Mn, Co, Zn, Eu, Cs and Ba and the corresponding radioactive tracers were added to batches of drinking water, estuarine water, sea water, ground water, twice-distilled water and ahumic material solution. After equilibration for 25 months, the following techniques were applied: passage through columns of Dowex Al chelating resin and ofsilylated silica gel, filtration through laminate membrane filters and chelating diethylenetriamine cellulose filters, precipitation with sodium diethyldithiocarbamate and l-(2-pyridylazo)-2-naphthol, extraction with ammonium pyrrolidinedithiocarbamate, and chelation by 8-quinolinol (oxine) followed by adsorption on activated carbon. The quantitative characteristics of these techniques and the influence of the water matrix effects are discussed, as well as the applicability for x-ray fluorescence analysis.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)93264-7
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“Trace analysis of estuarine brown algae by energy-dispersive X-ray fluorescence”. Sauter L, Van der Ben D, Van Grieken R, X-ray spectrometry 8, 159 (1979). http://doi.org/10.1002/XRS.1300080405
Abstract: Brown algae, which are good indicators for estuarine metal pollution, can advantageously be analysed by energy-dispersive X-ray fluorescence. The use of thin film samples and samples of intermediate thickness has several advantages over the conventional thick pellet procedure. A quite homogeneous thin target is prepared by suspending 15 mg of dried and ground seaweed powder in bi-distilled water and evaporating the slurry on a 10 cm2 Mylar foil held in a Teflon ring. The effective sample weight in the beam is calculated by a procedure based on the scatter peaks in the spectrum. Sensitivities are typically in the 215 ppm range. The coefficient of variation per analysis averaged over ten elements amounts to 10%. The natural concentration variation in seaweed specimens at one location is 13%. Samples from locations in the more polluted western Scheldt estuary yield significantly higher values for several elements, relative to the eastern Scheldt sites. Possible trace element variations between the top and base of plants, and between different seaweed specimens and sampling seasons, are discussed.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300080405
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“Sub-part-per-billion determination of total dissolved selenium and selenite in environmental waters by X-ray fluorescence spectrometry”. Robberecht HJ, Van Grieken RE, Analytical chemistry 52, 449 (1980). http://doi.org/10.1021/AC50053A017
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC50053A017
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“Radiometric diameter concept and exact intensities for spherical particles in x-ray fluorescence analysis”. Markowicz A, Van Dyck P, Van Grieken R, X-ray spectrometry 9, 52 (1980). http://doi.org/10.1002/XRS.1300090205
Abstract: In X-ray fluorescence analysis the concept of radiometric diameter, d, is often introduced in considerations of the fluorescent intensity from a particulate sample. It represents the mean geometric path of the X-rays through one particle and is usually simply taken to be equal to the volume-to-area ratio of the particle. The effective radiometric path is, however, itself dependent on geometry and absorption effects. Rigorous calculations of the fluorescent intensity from a particle in the π and π/2 geometries were carried out to evaluate the errors involved. It appears that, for π geometry, the discrepancy between these exact results and the intensity calculated via the use of d does not exceed 5.2%. For the π/2 geometry, the errors are much larger and can amount to 50% in realistic cases of X-ray fluorescence analysis. These conclusions are also applicable to monolayers. The effective radiometric diameter approaches d only when absorption effects become negligible, but is smaller in other cases.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300090205
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“Automatic absorption correction in x-ray fluorescence analysis of intermediate thickness samples using a dual external reference signal”. Van Dyck P, Markowicz A, Van Grieken R, X-ray spectrometry 9, 70 (1980). http://doi.org/10.1002/XRS.1300090209
Abstract: A method has been investigated which allows calculations from the X-ray fluorescence spectra of the absorption coefficients at any energy for any sample, without any additional measurement. Use is made of the ratio of the characteristic X-ray signals from a Zr wire positioned in front of the sample and from a Pd foil placed behind the sample, both in a fixed geometry. From the experimentally measured absorption coefficient at the Pd L energy (2.9 keV), the coefficients for higher energies are calculated. By the use of an iterative computer routine in which corrections for the enhancement of the Pd foil by the sample are also included, an accuracy of 2% or better on the absorption coefficient determination can be reached for homogenous samples in one measurement. Grain-size and heterogeneity effects induce inaccuracies on the absorption coefficient determinations which might well reach 20% for particulate samples like intermediate thickness deposits of geological materials. This approach thus has the same limitations as the classical transmission method for such heterogeneous samples.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300090209
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“Water analysis by spark-source mass-spectrometry after preconcentration on activated carbon”. Vanderborght BM, Van Grieken RE, Talanta : the international journal of pure and applied analytical chemistry 27, 417 (1980). http://doi.org/10.1016/0039-9140(80)80225-6
Abstract: For trace analyses of environmental waters, spark-source mass-spectrometry has been combined with a preconcentration procedure involving chelation of the dissolved trace elements with oxine and subsequent adsorption of the oxinates and naturally occurring organic and colloidal metal species onto activated carbon. The activated carbon is filtered off and ashed at low temperature. The residue is dissolved, an internal standard and pure graphite are added and, after drying, the electrodes are prepared. The photographically recorded mass spectrum is evaluated by a suitable computer routine. The error of the procedure is around 30%. While this preconcentration and analysis procedure is capable of measuring about 40 elements quantitatively, in practice 1025 trace elements are determined simultaneously above the 0.1-μg/l. detection limit, as is illustrated by analyses of drinking water, surface and ground water samples. Although a sophisticated technique, SSMS can be considered for regular panoramic survey analyses.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0039-9140(80)80225-6
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