Interelement Effects Research Articles

The determination of Fe, Zn and Pb in Zn-Pb ores by energy-dispersive X-ray fluorescence method

Energy dispersive X-ray fluorescence method for the determination of iron /3.5–26% of Fe/, zinc /0.5–9% of Zn/ and lead /0.05–5% of Pb/in zinc-lead ores containing arsenic has been worked out. In order to eliminate the interelement effect intensity correction equation had been proposed. The relative standard deviation of the determination varies from 3.6 to 9.2% depending on the element.

An Evaluation of Correction Algorithms, Using Theoretically Calculated Intensities

Several correction algorithms (Lachance & Traill (L-T), Rasberry & Heinrich (R-H), Lachance & Claisse (L-C) and Claisse & Quintin (C-Q) have been inter compared. All these algorithms assume that the effects of the matrixelements can be added in a linear way. Tertian, however, has shown that this is perfectly valid only when absorption is the only interelement effect to be taken into account. When enhancement is involved, corrections for crossed-effects are necessary. We have also evaluated the application of crossed-effect correction. Calculations were done, using theoretically calculated relative intensities. Influence coefficients were calculated by a regression method.

The Determination of Trace Amounts of Tin by Inductively Coupled Argon Plasma Atomic Emission Spectrometry with Volatile Hydride Method

A sensitive method is described for the determination of trace amounts of tin, based on continuous sodium borohydride reduction of tin in solution to gaseous stannane. The stannane generated is introduced into a relatively low-powered (1.6 kW) inductively coupled argon plasma source. The effects of a range of acids and interelement effects are investigated. Mixtures of nitric and succinic acids and of nitric and malic acids are the most suitable reaction media, especially in the presence of interferents. The method of standard additions is recommended for accurate tin determination. Compared to a conventional solution nebulization, the present system gives a sensitivity increase of a factor of approximately 3 orders of magnitude. The detection limit for tin is 0.05 ng/ml and precision values at 20 and 50 ng/ml Sn are less than 3% relative standard deviation. The linear calibration range spans nearly 5 orders of magnitude. The proposed method is applied to the determination of tin in low alloyed steels and in National Bureau of Standards standard reference materials (Cu-Ni alloy, orchard leaves, wheat flour, and rice flour).

Evaluation of an inductively-coupled plasma with an extended-sleeve torch as an atomization cell for laser-excited fluorescence spectrometry

An inductively-coupled plasma (ICP) with an extended-sleeve torch has been evaluated as an atomization cell for laser-excited fluorescence spectrometry. Limits of detection for 20 lines are given. The detection power is almost equivalent to that obtained by excitation with a hollow-cathode lamp. Interelement effects and spectral interferences are discussed.

Chemical Analysis of Portland Cement by Energy Dispersive X-Ray Fluorescence

Abstract X-ray fluorescence techniques have been applied for the analysis of portland cement for the past 20 or more years. During this time, applications have been developed primarily with wavelength spectrometers. In the past several years, development of solid state detectors has allowed energy dispersive X-ray fluorescence to detect and measure all the elements of interest in portland cement. Determination by energy dispersive X-ray fluorescence displays excellent precision, but a linear calibration of intensity versus concentration for many elements exhibits significant deviation from a straight line. Particle size effects that could cause errors in the calibration were minimized through fine grinding. The remaining factors responsible for nonlinear calibrations relate to interelement effects, which are usually considered as absorption and enhancement. The purpose of this investigation is to determine the interelement effects in portland cement and demonstrate the quantitative capabilities of energy dispersive X-ray fluorescence using certified National Bureau of Standards (NBS) portland cements as standard. An additional purpose is to demonstrate the application of empirical calculations for interelement effects in obtaining quantitative results utilizing Portland Cement Association check specimens as unknowns. Interelement effects in X-ray fluorescence are well documented with various techniques utilized. Many of these programs are complex and correct all elements for the presence of all other elements and require a large number of standards. The approach used by the author is an exponential model based on intensities of the interferring elements. Linear least squares fit of uncorrected intensities displayed absolute errors of 0.6% for alumina and silicon oxide to 1.0% for calcium oxide. Average deviations obtained following interelement corrections ranged from a low of 0.007% for potassium oxide to a high of 0.19% for calcium oxide. Analysis of each specimen consumed 200 s. The accuracy obtained by this method is well within the limits expected by the industry and the precision possible by alternate procedures.

The sorption of copper(II), manganese(II), zinc(II) and arsenic(III) onto human hair, and their desorption

Human hair has been studied in relation to sorption from aqueous solutions of Cu 2+, Mn 2+, Zn 2+ and AsO 3 3−. At an equilibrium concentration of 0.3 μg ml −1 the sorptions are relatively low for Mn (1.1 μg g −1) and As (0.1 μg g −1), and higher for Zn (10 μg g −1) and Cu (35 μg g −1). But only in the case of copper is the sorption significant relative to the indigenous levels of the elements in the hair. The greater sorption of Cu 2+ may be correlated with better binding to the hair fibre, probably both electrostatically and to the sulphur in the keratin. There appears to be at least three modes of attachment, or three mechanisms of attachment of Cu 2+ to the hair. An inter-element effect was observed, where Cu 2+ severely inhibits the sorption of Zn 2+ and Mn 2+. Also the total sorption of Cu 2+ is reduced on zinc or manganese-treated hair. Some comments are made regarding the results and the problems of exogenous contamination of human hair.

Progress in plasma source mass spectrometry

Development work in the application of the inductively coupled plasma to plasma source mass spectrometry is described. Two modes of operation are identified, boundary layer sampling and continuum (or bulk plasma) sampling. Boundary layer sampling is characterized by very high signal-to-background ratios, giving detection limits better than 1 ng ml −1 for a wide range of elements. The technique is applied to solution samples, nebulized at approximately 2.5 ml min −1. Samples may be processed at a rate of one every few minutes. The performance of the technique under boundary layer sampling conditions is illustrated by the rapid determination of lead isotope ratios in galena samples. Boundary layer sampling suffers from several disadvantages, including salt condensation on the sampling aperture, significant inter-element effects, and complex spectra for elements forming strongly bound oxides. It is currently limited to the analysis of simple solution samples. In order to overcome these disadvantages, continuum sampling has been introduced. System performance is compared to that achieved with boundary layer sampling, and the future potential of the technique in both modes of operation is discussed.

Application of a microprocessor-based portable XRF analyzer in minerals analysis

Applications of a new portable XRF analyzer are described in minerals exploration, mine control, process control and quality assurance. The analyzer uses a high resolution, room temperature proportional counter which, combined with a microprocessor, makes for a considerable improvement in sensitivity over instruments based on balanced filters. Also, concentration readout of up to 32 elements per measurement is made possible through stored coefficients for calibration and for correction of interelement effects.

The effects of C, P, and S on trace element partitioning during solidification in Fe‐Ni alloys

The effect of the minor elements P, S and C on the distribution coefficients of Ir, Ge, Ga, Au, Cu, and Cr between the solid and liquid phases in Fe‐Ni alloys was measured experimentally. Distribution coefficients for Ir, Ga, and Au increase with increasing P content while the distribution coefficients for Ir, Ge, and Ni increase with increasing C and S contents. For Ge, the distribution coefficient exceeds 1.0 when the P or C content of the solid exceeds 0.4 or 0.9 wt% respectively, or the S content of the liquid exceeds 7 wt%. The measured distribution coefficients were used in a solidification model of a parent body core. The model assumes fractional crystallization in which the distribution coefficients vary with composition and predicts the trace element distributions in the major iron meteorite groups. The model correctly predicts the observed trends for P vs. Ni and Au vs. Ni in the iron meteorite groups considered. Although the calculated trends for Ir vs. Ni and for Ge vs. Ni are relatively satisfactory for groups IVA and IVB, they fail to produce the observed trends for groups IIAB and IIIAB. Interelement effects of S and C on the distribution coefficients may explain these inconsistencies.

Spatial profiles of interelement effects in the inductively coupled plasma

Spatial profiles of interelement effects in the inductively coupled plasma

An overview of EXFNBS—A data reduction procedure for energy‐dispersive XRF with secondary target excitation

AbstractAn overview of a fundamental parameter, data reduction procedure for processing energy‐dispersive, x‐ray spectrometric data obtained with monochromatic excitation is described. The programs, called EXFNBS and NBSROI, are written in FORTRAN and correct for interfering x‐ray peaks, escape peaks, background, and x‐ray absorption/enhancement due to interelement effects in a speciment. This procedure is designed to operate in an interactive mode with a minicomputer in real time.

An Evaluation of the Rasberry-Heinrich Model for the Analysis of Silicate Rocks

The Rasberry-Heinrich model for correcting for absorption and secondary fluorescence effects is evaluated in the analysis of silicate rocks. The interelement effect of binary mixtures of the oxides of Na, Mg, Al, Si, K, Ca, Ti, Fe, and Mn is studied in a 1:11 fusion mixture with Li2B4O7. Two binary systems are expected to exhibit secondary fluorescence effects and are reported in detail. The combination Fe2O3/TiO2 shows a small secondary fluorescence, whereas the Al2O3/SiO2 binary shows an absorption effect. The latter effect is attributed to the large absorption effect due to oxygen. The secondary fluorescence of its Fe2O3/TiO2 system in a diluted matrix of Li2B4O7 acts like a negative absorption rather than secondary fluorescence as described by the Rasberry-Heinrich model.

Effects of season and seawater concentrations on trace metal concentrations in organs of Mytilus edulis.

Concentrations of Pb, Cu, Zn, Fe, and Mn were measured in the gills and visceral mass ofMytilus edulis (mussels) and in the surrounding seawater (as dissolved ions and suspended particulate matter) over a one-year period (at monthly intervals) from two locations in British Columbia. Higher concentrations of Pb, Zn, and Cu were observed in tissues of mussels taken from the location containing higher levels in the seawater. All elemental concentrations in the mussels, except copper, could be correlated with seawater (dissolved ion) concentrations. Seasonal variations occurred in the Pb, Zn, Cu, and Fe mussel tissue concentrations but only occurred for soluble Fe and Zn in the surrounding seawater. Significant correlations were observed between Cu concentrations in both organs and Pb and Zn concentrations in seawater, suggesting an interelemental effect, facilitating copper uptake.

Influence of interelement effects on x‐ray fluorescence calibration curve coefficients for binary mixtures

AbstractIt has been shown that x‐ray fluorescence calibration curve coefficients are closely related to matrix effects, such as absorption or absorption plus enhancement of the fluorescent radiation. In the classical paper of Rasberry and Heinrich,1 a single coefficient (named Aik) calibration curve was proposed when pure absorption is the predominant effect on the spectral line of interest. Similarly, and for practical purposes, a single coefficient (named Bik) was also considered when absorption and enhancement are present. We propose a new interpretation of calibration curve coefficients based on analytical expressions obtained recently for binary compounds under monochromatic excitation. Six distinct possible cases of calibration curves arise. Examples of binary compounds for each case are given. The data considered have been computed using the fundamental parameters method which allowed us to study a large number of possible mixtures for an arbitrary monochromatic excitation. Finally, through a different approach we discuss how this analysis could be extended to consider polychromatic excitation.

Energy Dispersive XRF Analysis of Lubricating Oil Additives with Secondary Target Excitation and the EXACT Fundamental Parameters Program

The need for rapid and accurate analysis of lubricating oil additives is firmly established by the petroleum industry. The application of energy dispersive X-ray fluorescence spectrometry techniques to this analysis is a valuable aid in achieving reliable and fast quality control of these product types.Due to the large concentration variations possible for the elements of interest within these materials (principally Zn, Ca, P, S at 0-20%), interelement effects can become significant. In order to correct for interelement effects, historical XRF methods have relied on a large number of standards for each element to be determined or matrix matching with standards closely bracketing the unknown sample concentrations.

The Analysis of Oil Additives Using Fundamental Influence Coefficients

One of the most important applications o£ XRF in the oil industry has been in the analysis of oil additives which range from Mg to Ba. In such a low atomic number, hydrocarbon matrix, small variations in the additives cause pronounced changes in the average atomic number of the matrix and hence give rise to strong interelement effects. In recent years a number of mathematical methods have been developed to correct the measured X-ray intensity of the analyte litie for these considerable effects. This paper describes a method for the determination of Zn,Ba,Ca,CI,S,P and Mg in oil additives using a concentration based correction model in which influence coefficients (alphas) are applied.

"Standard-Background" Method of X-Ray Spectral Analysis for Quality Control of Noble Metals in Alumina-Based Automobile Exhaust Catalysts

Development of matrix correction procedures in the field of X-ray spectral analysis leads usually to “universal” algorithms which allow use of a common calibration equation for assay of various materials with different composition and concentration ranges. In many applications, such methods can guarantee accuracy of 3-5% rel.For X-ray analysis of automotive catalysts, one such technique is based on the theoretical correction of interelement effects. The article states that “the overall accuracy of this approach is about 10% relative error, although this may vary depending upon the particular specimen being analyzed.” However, narrow specification limits for the quality control of catalysts require the total error of analysis less than 1-1.5% rel.

Powder dilution as a new method of elimination of interelement effects in energy-dispersive X-ray fluorescence analysis

If the concentration of elements with Z>22 (Ti) is to be determined in mineral samples and if the concentration of any of these elements is greater than ≈ 1%, the sample is diluted by grinding it together with an appropriate amount of quartz powder in an agate mortar mill. The diluted sample is measured in powdered form in a spectro-cup at practically infinite thickness by energy-dispersive X-ray fluorescence; the counting rates are corrected by means of the Compton scattering peak and evaluated by use of calibration curves obtained by measuring standards on the basis of silica gel. The applicability of this method is established by measuring the concentrations of 12 elements with Z>22 in 14 mineral samples of varying composition.

Inter-element effects and suppression of interferences in the determination of nickel by u.h.f. plasma torch emission spectrometry

Several metals show enhancing and depressing effects in the determination of nickel by u.h.f. plasma torch emission spectrometry. To suppress these interferences and to improve the sensitivity, the addition of potassium, magnesium and iron was examined; Mg and (Fe + Mg) spectroscopic buffers were found to minimize interference effects, and improve the sensitivity; the detection limit was 5 μg Ni l -1 in the presence of magnesium. The procedure is applied to the determination of nickel in iron and steels.

Spectroscopic study of atomization processes and inter-element effects on the flame emission of chromium and iron in an air—acetylene flame

Emission spectroscopy is applied for characterization of reactions occurring in air—acetylene flames normally used for atomic absorption spectrometry. Inter-element effects on the emissions of chromium and iron are discussed. Two atomic emission lines with different upper energies and a molecular emission line of the diatomic oxide MO are compared for determination of the excitation temperature and the degree of atomization in fuel-rich and lean flames. The reductive power of the fuel-rich flame is essential for atomization of chromium salts. Inter-element effects by iron can be attributed to the formation of refractory oxides, and to mutual catalytic oxidation.