Quantitative Analysis Of Major Elements Research Articles

On-line quantitative analysis of major elements in phosphate slurry using LIBS assisted by plasma information from orthogonal directions imaging

To solve the lag of chemical element information feedback and realize the on-line analysis of phosphorite flotation, LIBS was used to measure major elements in the phosphate slurry. Plasma images in two orthogonal directions were captured synchronously to describe the irregular plasma. The plasma image projections in different directions were calculated as the features. A spectral correction method with these features was proposed to solve the problems of large signal fluctuations and poor measurement accuracy. The proposed method was first applied in the filed application of phosphate slurry on-line analysis. The RSDs of the characteristic spectral intensity decreased from more than 20 % to less than 3 %, improving the stability of spectra significantly. The method was further combined with the calibration of the concentrations of P2O5, MgO and SiO2. The R2 and MAE of P2O5 were 0.99 and 0.5 %, respectively, meeting the accuracy requirements of online measurements.

Application of elastic net in quantitative analysis of major elements using Martian laser-induced breakdown spectroscopy datasets

Multiple sets of laser-induced breakdown spectroscopy (LIBS) instruments, including ChemCam (Curiosity), SuperCam (Perseverance), and the Mars Surface Composition Detector (MarSCoDe, Zhurong), are working currently on the surface of Mars, a booming scene of LIBS technology application to planetary exploration. One of the primary challenges faced by those LIBS instruments is accurate and quantitative chemical composition determination of unexplored geological targets. Elastic net is a linear regression model that combines ridge regression and lasso model, which inherits the sparseness of lasso and the stability of ridge. In this work, we investigated the spectral features selected by elastic net model, the model performance and application to over 23,000 LIBS points. Selected features exhibit significant emission lines that are attributed to a certain single element and a few lines attributed to other related elements. These features enhance the interpretability of the model and weaken the matrix effect in LIBS quantitative analysis. In comparison, the results of elastic net are comparable and may be slightly better in some cases than other common linear regression models. For igneous calibration targets (norite, picrite, and shergottite), the predictions of elastic net are closer to the values measured in Earth laboratory than the final multivariate oxide composition values predicted by ChemCam team. Finally, we predicted the oxide abundances of 8 major elements from Mars LIBS spectra of over 23,000 points using elastic net. The predicted values of the elastic net models are highly correlated with those from the ChemCam team model. These results indicate that elastic net is viable for quantitative analysis Mars LIBS spectra. We propose that elastic net is an important candidate model for the quantitative analysis of the Zhurong MarSCoDe LIBS spectra.

Compositional Analysis of Chalcopyrite Using Calibration-Free Laser-Induced Breakdown Spectroscopy

This article presents elemental analysis of an economically important mineral (chalcopyrite) of local origin. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) methodology based on the assumption of optically thin plasma and local thermodynamic equilibrium was employed for quantitative analysis. Plasma on the surface of the chalcopyrite target was generated by an Nd:YAG laser beam of wavelength 532 nm, pulse width 5 ns, and operated at repetition rate of 10 Hz. A LIBS2000+ detection system, comprised of five spectrometers, covering the spectral range from 200–720 nm, was used to record the signal of the optical emission from the chalcopyrite plasma. Recorded optical spectrum revealed the presence of Cu and Fe as the major elements while Ca and Na were recognized as the minor elements in the target sample. Quantitative analysis has shown that the relative concentrations of Cu, Fe, and Ca in the sample under study were 58.9%, 40.2%, and 0.9% by weight respectively. However, Na was not quantified due to the unavailability of suitable spectral lines, required for CF-LIBS analysis. Results obtained by CF-LIBS were validated by X-ray fluorescence (XRF) analysis, which showed the presence of five compositional elements viz. Cu, Fe, Si, Se and Ag with weight percentages of 58.1%, 35.4%, 5.7%, 0.7%, and 0.1% respectively. These results endorse the effectiveness of the CF-LIBS technique for quantitative analysis of major elements, however, its usefulness in case of minor and trace elements needs further improvement.

Calibration-free analysis of immersed brass alloys using long-ns-duration pulse laser-induced breakdown spectroscopy with and without correction for nonstoichiometric ablation

Long-ns-duration, single pulse laser-induced breakdown spectroscopy (LIBS) is known to be an effective method to observe well resolved spectra from samples immersed in water at high hydrostatic pressures. The aim of this study is to investigate whether the signals obtained using this method are suitable for quantitative analysis of chemical composition. Six certified brass alloys consisting of copper (Cu), zinc (Zn) and lead (Pb) were measured underwater using a laser pulse of duration 250ns, and their compositions were determined using calibration-free LIBS (CF-LIBS) and corrected CF-LIBS (CCF-LIBS) methods. The mass fractions of Cu and Zn calculated using CF-LIBS showed better agreement with the certified values than those determined using CCF-LIBS, with relative errors of Cu 4.2±3.3 % and Zn 7.2±6.4 %. From the results, it can be said that the difference of preferential evaporation and ablation among elements does not need to be considered for underwater measurements with the long-pulse LIBS setup used in this work. While the results indicate that the CF-LIBS method can be applied for in situ quantitative analysis of major elements with concentrations>~10 %, the mass fractions determined for Pb, with concentrations<5 % had large relative errors, suggesting that an alternative method is required to quantify minor elements.

Elemental analysis of white electrical tapes by wavelength dispersive X-ray fluorescence spectrometry

The aim of this study was to analyze and discriminate electrical tapes using the wavelength dispersive X-ray fluorescence (XRF) spectrometry and statistical techniques. The backings of 46 white electrical tapes were analyzed. A discrimination of 90.4% was performed only by quantitative analysis of major elements (relative ratio of Cl to Ca). Ten distinct groups with a discrimination of 78.9% were yielded only by qualitative analysis of trace elements. Ninety-nine electrical tape pairs which could not be discriminated by major elements were further compared with the characteristics of trace elements. The overall discriminating power of 96.1% was obtained by the combination of quantitative and qualitative analysis. The ability of XRF technique to discriminate different electrical tapes was similar to several well-known methods combined.

A simple LIBS method for fast quantitative analysis of fly ashes

An evaluation of quantitative analysis of major elements (Ca, Al, Mg, Si and Fe) present in fly ashes was made using a simple and cost effective LIBS system. LIBS parameters were optimized to obtain best sensitivity and repeatability. In this purpose different binders were compared, leading to best sensitivity and mechanical stability when a binder containing silver and cellulose was employed in a 1:1 mass ratio. In order to be able to determine major elements in different fly ashes, a multi-matrix calibration was employed. Four reference materials were employed for calibration and five other fly ashes were selected as sample. Concentrations obtained by LIBS were compared to wet acid digestion and alkali fusion followed by ICP-OES analysis. Ca, Mg, Fe, Si and Al concentrations found using the LIBS method developed were in a good agreement with the values obtained by classical methods.

Interpretation of discordant U–Pb data of zircon: Alteration and radiation-damage effects

The durability of zircon is decreased by the radiation damage caused by the α-decay of constituent actinides. The low crystallinity zircons are more susceptible to alteration and easily release Pb from the structure. U-Pb analysis of the low crystallinity zircon often shows discordant data. However U-Pb system and chemical stability of altered zircon is not well understood due to complex reaction process. In this study, we discussed the condition and timing of alteration event of zircon in the Franceville site from U-Pb geochronology and rare earth elements (REE) geochemistry of accessory minerals. Samples were taken from Bidoudouma which is located 63km north from Oklo, the Republic of Gabon. Quantitative analysis of major elements was carried out by EPMA. Insitu U-Pb and REE analyses of apatite, titanite and zircon were performed by using a SHRIMP at Hiroshima Univ. U-Pb data of the Franceville zircons show the maximum deposition age of 2083±6 Ma. As shown in Figure, some zircons show discordant U-Pb data and high content of nonformula elements, which indicates that U-Pb system of the zircon was disturbed around 500 Ma by alteration. Apatite grains which are euhedral and unaltered indicate the mineralization age of 2075±130 Ma, which is consistent with U-Pb data of the unaltered zircon. Some titanite grains show dissolved texture. Comparison of accessory minerals suggests that the alteration of zircon and titanite occurred through the interaction with alkaline hydrothermal fluid.

Evaluation of operational parameters affecting semiquantitative multi-elemental analysis by inductively coupled plasma mass spectrometry

A systematic study was carried out on the effect of ICP-MS operational parameters, such as dwell time, sweeps per reading, readings per replicate and number of replicates, on the precision and accuracy of results obtained in the semiquantitative mode by using Rh as internal standard and Ge, In and Bi for internal calibration of the instrument. In order to improve the quantitative analysis of major elements, such as Na, Mg, K and Ca, the detector attenuation (OmniRange parameter) must be recalibrated by using a multi-standard solution of these elements. Under these conditions, accurate results were obtained with a total measurement time of 103 s per sample, covering the whole mass range from 6 to 238 µ. The applicability of the methodology developed was confirmed by the analysis of a drinking water certified reference material.

Quantitative analysis of major elements in silicate minerals and glasses by micro-PIXE

The Guelph micro-PIXE facility has been modified to accommodate a second Si(Li) X-ray detector which records the spectrum due to light major elements (11 ≤ Z ≤ 20) with no deleterious effects from scattered 3 MeV protons. Spectra have been recorded from 30 well-characterized materials, including a broad range of silicate minerals and both natural and synthetic glasses. Sodium is mobile in some of the glasses, but not in the studied mineral lattices. The mean value of the instrumental constant H for each of the elements Mg, Al, and Si in these materials is systematically 6–8% lower than the H-value measured for the pure metals. Normalization factors are derived which permit the matrix corrections requisite for trace-element measurements in silicates to be based upon pure metal standards for Mg, Al and Si, supplemented by well-established, silicate mineral standards for the elements Na, K and Ca. Rigorous comparisons of electron microprobe and micro-PIXE analyses for the entire, 30-sample suite demonstrate the ability of micro-PIXE to produce accurate analysis for the light major elements in silicates.

Investigation on SIMS Quantification of Major Elements of CdxHg1-xTe(CMT).

It is well-known that quantitative analysis of major elements by SIMS is generally difficult because of the matrix effect. In the present paper we examined some basic problems of the major element analysis of CdxHg1-xTe (CMT) which is known to be easily damaged by various kinds of beams. It was shown that the matrix effect in quantification can be reduced by detecting postionized monoatomic ions for O2+ and Ar+ primary beams. In the case of Cs+ bombardment, detection of the cationized molecular ions, which are formed via one kind of post-ionization process, also proved to be effective. In all the cases, good linear relationships between the secondary ion intensity and the primary ion current density were obtained in the log-log plot. The intensity decrease of Hg+, however, was observed along with depth profiling of the bulk sample. This phenomenon was correlated with the morphological changes caused by ion irradiation.