Interelement Effects Research Articles

Iron Determination in Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Study of Spectral and Interelement Effects at Different Wavelengths

Abstract Four analytical wavelengths of iron (238.204, 239.562, 259.940, and 240.488 nm) were tested for determination of Fe in fertilizers by inductively cou pled plasma atomic emission spectroscopy (ICP AES). Variations in measurements were caused by the changing interference pattern at different wave lengths evaluated by multiple linear regression. Thus, results obtained with different wavelengths are not comparable. Ca, P, and K were typical ele ments causing interference in almost all examined Fe wavelengths. Wavelength Fe II 238.204 nm is the best wavelength for determination of Fe in fertiliz ers by ICP-AES. Method accuracy is ± 8% at the ex amined Fe levels in fertilizers.

Determination of Magnesium in Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Studies of Some Spectral and Interelement Effects at Different Wavelengths

Abstract Four analytical wavelengths of magnesium were tested for determination of Mg from fertilizers by inductively coupled plasma atomic emission spectroscopy (ICP-AES): 202.528, 285.213, and 383.826 nm (Mg I) and 279.553 (Mg II). The effects of fertilizer matrix elements on Mg determination were examined by adding matrix elements to fertilizer solutions. Multiple linear regression calculations proved a valuable technique for evaluating the effects of matrix elements on Mg determination. The observed interferences at Mg wavelengths may be both spectral and interelement. Interelement effects were typically caused by Na, K, and Ca, and spectral effects, by P, Fe, and S. The best wavelength for determination of Mg in fertilizers by ICP-AES was 383.826 (Mg I).

A taylor series model to evaluate the interelemental effects in X-ray fluorescence analysis, applied to the iron-zirconium-diluent system

A semi-empirical model has been developed to quantify the interelemental effects in X-ray fluorescence analysis. The measured X-ray fluorescence intensity has been expressed as a function of the different fluorescence elements composing the sample. this complex function has become an operative function via a Taylor series development. An explication has been given for the significance of the different terms of the series. These terms respond to mathematical functions known as characteristic functions for each chemical system. A parameter (B) has been defined which makes it possible to quantify the influence of the interelemental effect as a function of the analyte concentration (C) and that of the concomitant elements. The proposed model has been applied to the Fe-Zr-diluent chemical system. Simple relationships between B vs C have been obtained independently considering iron or zirconium as analyte.

Analysis of archaeological pottery by X‐ray fluorescence spectrometry applying the limit dilution method

AbstractA method for correcting the intensity of x‐ray fluorescence (limit dilution method) is proposed for the analysis of samples with a complex matrix such as ceramic materials of archaeological interest. This method corrects the interelement effects, resolving the wide deviations which occur in the quantitative results obtained by x‐ray fluorescence without correction. The contents of sodium, magnesium, aluminium, silicon, potassium, calcium, titanium and iron in sixteen archaeological ceramic samples of different origins and from different locations were determined. The results obtained are comparable to the values obtained by chemical analysis. A statistical study of the data was carried out to classify the samples hierarchically by cluster analysis of their chemical composition and loss on ignition.

Correcting for background and inter-element effects in glow discharge optical emission spectrometry

The background signal in glow discharge optical emission spectrometry (GD-OES) is shown to comprise at least four components: a constant term, an argon term, a matrix continuum term and a matrix line term. The constant term includes photomultiplier dark current and other noise sources, the argon term is emission from excited argon atoms in the plasma, the matrix continuum is from continuum emission from the sputtered material, and the matrix line term is from line interferences, so called inter-element effects. Iron is shown to be a major source of continuum background. A simplified equation is provided for the GD-OES background which is shown to increase the dynamic range in depth-profiles and reduce depth-profiling artefacts by correcting for changes in the background signal with changes in the matrix during sputtering and by reducing inter-element effects.

Correction parameters in X-ray fluorescence analysis applying the limit dilution method (LDM)

This paper is a study of the interelemental effect and its correction based on the mathematical model used to develop LDM in XRF analysis. A compensation coefficient is defined which is obtained from the quotient of the mass absorption coefficients of the problem and the standard (μ s * /μ p * ). This coefficient compensates the effects produced by interactions between the analyt and the interferences and therefore acts as a correction factor for the interelemental effect within this theoretical model

Correction parameters in X-ray fluorescence analysis applying the limit dilution method (LDM)

This paper is a study of the interelemental effect and its correction based on the mathematical model used to develop LDM in XRF analysis. A “compensation coefficient” is defined which is obtained from the quotient of the mass absorption coefficients of the problem and the standard (μs*/μp*). This coefficient compensates the effects produced by interactions between the analyt and the interferences and therefore acts as a correction factor for the interelemental effect within this theoretical model. The model itself establishes a simple relation of the “compensation coefficient” and the Y/H correction parameters for the unknown and the standard. An algorithm is proposed for calculating the “compensation coefficient” following an algebraic procedure. The proposed method has been applied to XRF analysis of samples consisting of iron and zirconium mixtures and clays. In all cases a satisfactory correction of the interelemental effect has been achieved.

Evaluation of the interelemental effect in X-ray fluorescence analysis by the total addition method

An algorithm for quantifying interelemental effects in X-ray fluorescence techniques is developed. By applying an addition process, the ratio between the mass absorption coefficients of the analyte and the unknown sample (μi*/μs*) is calculated to correct the fluorescence intensity of the element to be determined and linearize the I-c calibration plot. This coefficient can be calculated graphically and numerically. The method is applied to the determination of tin in lead alloys with good results over wide concentration ranges.

Determination of impurities in lead zirconate–titanate electroceramics by inductively coupled plasma atomic emission spectrometry

An analytical method was developed for the determination of Al, Ba, Ca, Hf, Mg, Si and Sr impurities and Co, Cr, Cu, Fe, Mn, Nb, Ni, P, W and Zn dopants in lead zirconate–titanate (PZT) electroceramics by inductively coupled plasma atomic emission spectrometry. A niobium-doped dense PZT ceramic sample was used. Sample dissolution was achieved by using: decomposition with HF + H2SO4 in a poly(tetrafluoroethylene)-lined pressure vessel at 170 °C for 16 h followed by evaporation to dryness and dissolution of the residue with HCl; decomposition with (NH4)2SO4+H2SO4 in a glass beaker followed by evaporation to dryness and dissolution of the residue with HCl; and fusion with Li2B4O7 in a graphite crucible and dissolution of the melt with 1+24 v/v HNO3. For each element, an analytical line free from spectral interference was selected. The decomposition reagents present in the final solutions of the sample (HCl and Li2B4O7–HNO3), and the Ti and Zr macro-constituents, decrease the emission signals substantially. Nevertheless, the inter-element effect of Pb is negligible. The correction of these matrix effects was carried out by preparing standard solutions, for obtaining detection limits, and calibration by matrix matching. The 3σ detection limits of the impurities were determined using the three decomposition methods and correction of the matrix effects. The lowest values of the detection limits were obtained using acid decompositions, and were between ≈0.1 µg g–1 for CaO, MgO and SrO, and 461 µg g–1 for P2O5. The analytical results obtained for 17 minor and trace elements using the three decomposition methods were in excellent agreement. Good precision and accuracy were attained; the relative standard deviations for the results obtained for each element for each dissolution method ranged in general from 3 to 7%.

Inductively coupled plasma—atomic emission spectrometry (ICP-AES): an analytical technique for the chemical characterization of perovskite ceramic semiconductors

The possibilities of inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the chemical characterization (dopants, impurities, and macroconstituents) of perovskite ceramic semiconductors (PTC thermistors, varistors, manganites, cobaltites) are shown. The dissolution of the samples is achieved by five methods: (a) decomposition with HCl in a Teflon-lined pressure vessel, (b) decomposition with HF + H 2SO 4 in a Teflon-lined pressure vessel, (c) decomposition with (NH 4) 2SO 4 + H 2SO 4 in a platinum dish, (d) fusion with Na 2CO 3 + Na 2B 4O 7 in a platinum crucible, (e) fusion with Li 2B 4O 7 in a graphite crucible. The spectral interferences and the inter-element effects are studied and corrected. The detection limits are comprised, approximately, between 0.00001% and 0.1%. High sensitivity and good precision are attained.

Computer Procedure for Resolving Overlapped Peak in X-Ray Fluorescence Spectrometry

Trace element analysis of geological samples by X-ray fluorescence technique presents certain difficulties due to numerous peak overlaps and interelement effects. In this work limitations in spectrum analysis due to overlap interferences are discussed and have largely been overcome in the region from potassium to copper using correction software program “OVERLAP”. Two sets of standard samples were used to testfy for the precision of the results obtained.

NCSXRF: A General Geometry Monte Carlo Simulation Code for EDXRF Analysis

EDXRF analysis is conveniently split into two parts: (1) the determination of X-ray intensities and (2) the determination of elemental amounts from X-ray intensities. For the first, most EDXRF analysis has been done by some method of integrating the essentially Gaussian distribution of observed full energy pulse heights. This might be done, for example, by least-square fitting of Gaussian distributions superimposed on a straight line or a quadratic background. Recently more elaborate shapes of the energy peaks also have been considered (Kennedy, 1990). After the X-ray intensities have been determined, interelement effects between the analyte element and other elements must be corrected for in order to obtain the elemental amounts from X-ray intensities. This correction can be done either by an empirical correction procedure as in the influence coefficient method which requires measurements on a number of standard samples to determine the required coefficients, or by theoretical calculation as in the fundamental parameters method which does not require standard samples.

New Developments in FP-Based Software for Both Bulk and Thin-Film XRF Analysis

In the last decade, the Fundamental Parameter (FT) method has been increasingly used in quantitative XRF analysis as an effective means for interelement effect corrections. Many authors have contributed to its continuous development both in theory and practice [1 - 26]. Among various implementations, the FP-alpha method has been used widely in bulk-sample analysis because of its unique advantage of speed [1 - 6]. In recent years, however, with the advent of faster computers, a rigorous full FP approach has become feasible and practical. This is especially true in the field of multilayer thin-film, analysis, where the FP-alpha approach has not yet been applied.

Spectrochemical Determination of Some Elements in Zinc Samples Using Glow Discharge Lamp

Abstract Results in spectrochemical analysis with optical emission spectroscopy(OES) are affected by matrix. Analysis of zinc samples are difficult with other emission excitation sources as arc and spark, since zinc is a volatile element. For this reason, metallic zinc samples and its low alloys were analysed by using a glow discharge lamp in this work. Interelement effects were also investigated in the determination of Al, Cu and Mg in the samples.

X-Ray Fluorescence Calibration with Partial Least-Squares

X-ray fluorescence (XRF) spectrometry is a popular method for noninvasive elemental analysis of a wide variety of sample types. Unfortunately, applications of XRF are complicated by the occurrence of interelement effects, which make the measured intensities complex functions of multiple-element concentrations. In this work, an implicit modeling method, partial least-squares (PLS), was used to correct for interelement effects in x-ray fluorescence analysis. Instead of fitting XRF peak intensities and concentrations to classical explicit models, the XRF spectra of a set of standard samples were used to build PLS models, implicitly relating the XRF spectra to the concentrations. Methods for the pretreatment of spectra are compared for a set of nickel alloy samples containing Fe, Cr, Ni, Mn, Mo, Ti, and Si. The PLS calibration method using appropriately preprocessed spectra gives the best results, when compared to the results from the literature and from a conventional explicit calibration model (MLR method).

Chemical analysis of impurities in zirconia and aluminium nitride ceramics by inductively coupled plasma atomic emission spectrometry

Inductively coupled plasma atomic emission spectrometry (ICP-AES) has been used for the determination of the most significant impurities (Al, Ca, Fe, Mg, P, Si and Ti) in zirconia and aluminium nitride ceramics according to the following procedure: (i) development of two decomposition methods for each material; (ii) study of spectral interferences, matrix and interelemental effects; and (iii) determination of the detection limits. Good precision and accuracy were attained. The procedures developed in this work can be applied to zirconia partially stabilised by the addition of CaO, MgO or Y2O3, tetragonal zirconia polycrystals with the addition of Y2O3, pure aluminium nitride or aluminium nitride with additions of alkaline earth oxides, Y2O3 or CeO2.

Flow Injection Analysis - Inductively Coupled Plasma/Mass Spectrometry: Study of Interelement Effects

Abstract A flow injection analysis - inductively coupled plasma/mass spectrometry (FIA/ICP/MS) system is described using a Sciex Elan Model 250 ICP/MS system coupled with a peristaltic pump and injection valve. Sample volumes of 25 μl are injected and samples can be measured at the rate of one per minute. Addition of nitric acid to the carrier generally enhanced and stabilized the recorded signals. Also, the nitric acid tended to lessen interelement effects. Most interelement effects were fairly constant above 0.1 pm added element.

Determination of molybdenum and tungsten at trace levels in rocks and minerals by solvent extraction and X-ray fluorescence spectrometry

Separation by solvent extraction followed by X-ray fluorescence spectrometry has been used for determination of molybdenum and tungsten in rocks and minerals. Samples are decomposed either by heating with a mixture of hydrofluoric acid and perchloric acid or by fusion with potassium pyrosulphate, followed by extraction of molybdenum and tungsten with N-benzoylphenylhydroxylamine in toluene from 4–5 M sulphuric acid medium. The extract is collected on a mass of cellulose powder, which is dried in vacuum, mixed thoroughly and pressed into a disc for XRF measurements. The method is free from all matrix effects and needs no mathematical corrections for interelement effects. The method is suitable for determination of molybdenum and tungsten in geological materials down to ppm levels, with reasonable precision and accuracy.

14 MeV neutron activation analysis of ternary copper ilver selenide by X-ray and gamma-ray spectrometry

14 MeV neutron activation of ternary copper silver selenide gives rise to a predominant activity from the 0.511 MeV annihilation peak from the three elements when γ-ray spectrometry is used. To overcome the interference problems, X-ray spectrometry was applied to the simultaneous nondestructive determination of silver and selenium, after which copper can be determined by γ-ray spectrometry. The results of analysis show a relative error not higher than ±5%, when the samples were diluted with H3BO3 /≃90%/ to minimize the interelement effects.

Simultaneous determination of four components by X-ray spectrometry after 14 MeV neutron activation

14 MeV neutron activation followed by X-ray spectrometry was applied to the simultaneous nondestructive determination of cadmium, antimony and bromine, utilizing praseodymium as an internal standard. The results of analysis show a relative error not higher than ±5%, when the samples were diluted with H3BO3 ⊂-5% to minimize the interelement effects.