Trace Elements In Solid Samples Research Articles

Quantitative imaging of trace elements in solid samples by online isotope dilution laser ablation-inductively coupled plasma-mass spectrometry.

For quantitative visualization of trace elements, an online isotope dilution (ID) laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) method capable of accurately correcting the detection amount of targets is presented. Two aerosols from an ablated sample and a nebulized isotopically enriched spike solution were mixed online using a dual-port spray chamber. In this paper, transmission efficiency (TE) of each of the two gas streams to the ICP-MS detector is revealed, and the quantification values were corrected by including the ratio of TEs in the calculation of the online ID method. To verify the developed method, Fe and Sr as model elements in five certified reference materials (CRMs, glass: SRM 610, 612, 614, alloy: SS-356, -383) were quantified without the use of matrix-matched CRMs. The resultant values agreed with the certified values of CRMs in the range of 92.7-104.7% and 92.8-109.0% for Fe and Sr, respectively. The LODs (3σ) were 0.54 and 0.17 μg g-1 for Fe and Sr, respectively. In addition, the applicability of this method to quantitative imaging of unknown solid samples was demonstrated for actual biological hard tissues (a mouse incisor, human primary tooth, and fish otolith) using the result of shot-analysis. The results were consistent with the reported concentration range obtained by wet chemical analysis.

Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Based on Melting of the Donor Phase: a New Approach for the Determination of Trace Elements in Solid Samples

A novel ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) based on melting of the donor phase for the determination of Cd, Cu, and Fe in margarine samples using high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS) is proposed. Considering that margarine is in the solid phase at room temperature, requiring heat for melting, the microextraction process was assisted by an ultrasonic bath to ensure the melting point of the samples and to increase the extraction efficiency of the analytes by UA-DLLME. After the extraction procedure, the aqueous phase was collected and directly introduced into a graphite furnace. The procedure was applied for extraction and multi-element determination, exploring the strategy of simultaneous and sequential determination of analytes by HR-CS ET AAS. A low volume of nitric acid solution in the presence of ethanol and hydrogen peroxide allowed the metals to be separated from the sample in an aqueous phase with subsequent determination by HR-CS ETAAS. In the extraction procedure, 5.0 g of each margarine sample was sonicated under heating in the presence of 100 μL of a solution containing HNO3 0.1 mol L−1, ethanol (95.1%, v v−1), and H2O2 3% (v v−1) in a volume proportion of 2:1:1. The influences of the time of extraction, temperature of extraction, and amplitude of sonication were examined, and the proposed conditions were as follows: extraction time, 10 min; temperature, 60 °C; and amplitude, 100%. Using 5 g of margarine sample, limits of detection of 0.03, 0.52, and 224 ng g−1 were obtained for Cd, Cu, and Fe, respectively. Recovery tests were performed, and the results ranged from 87 to 108% for Cd, 91 to 115% for Cu, and 85 to 112% for Fe. The results obtained by the proposed extraction procedure agreed with those obtained after wet digestion of the sample and determination by inductively coupled plasma optical emission spectrometry (ICP OES).

A Comparison of ETV and LA for the Determination of Trace Elements in Solid Samples by MIP OES

AbstractThe performance of electrothermal vaporization (ETV) and laser ablation (LA) of dry aerosols as sample introduction systems for microwave induced plasma optical emission spectrometry (MIP OES) are compared and evaluated in terms of detection limits, precision and accuracy for the determination of trace elements (Ca, Cd, Cu, Fe, Mg, Mn, Sr, Zn) in the same solid micro samples. In MIP OES both radiation sources can be independently adjusted to optimize the sampling process and then its subsequent excitation. A univariate approach and simplex optimization procedure were used to obtain the best signal/noise (S/N) ratio and derive analytical figures of merit. A comparison using a Student’st-test between the results obtained by both ETV/LA-MIP OES methods for trace elements, and concentrations in standard reference material (SRM) and certified reference materials (CRMs) showed that there was no significant differences on a 95 % confidence level. The detection limits of the tested elements in solid samples by ETV/LA-MIP OES were in the range of 0.1 to 11 µg g−1for all elements determined, while the corresponding absolute values in the range of ng. The precision of the results for ETV-MIP OES and LA-MIP OES varied between 2 and 4 % and 3 and 7 %, respectively. The linear dynamic ranges in the ETV/LA-MIP OES are extend over three decades of concentration. The methods were validated by the analysis of NIST SRM 2711Montana Soil, NRCC CRM PACS-2 Marine Sediment and NRCC CRM TORT-2 Lobster Hepatopancreas of different matrix composition and by the standard addition technique.

Crucible Atomizers Open Up New Opportunities for the Atomic Absorption Analysis of Trace Elements in Solid Samples with the Use of Fractional Evaporation

The atomic absorption analysis of trace elements in natural solid samples with the use of an improved crucible atomizer with several condensation/evaporation zones is shown to be advantageous. A new approach to fractional preconcentration is proposed, including two stages of thermal decomposition (high-temperature and low-temperature) of solid sample components when elements are evaporated and their vapors are condensed in heated and unheated zones. This approach facilitates the efficient suppression of non-selective interferences and matrix effects. It also improves the metrological characteristics of the element analysis of samples of complex composition.

Determination of elemental concentration in geological samples using nanosecond laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) can be used for measuring the concentrations or ratios of various trace elements in solid samples.

Spectral Analysis of Trace Fluorine Phase in Phosphogypsum

Phosphogypsum, which contains more than 90% of the calcium sulfate dehydrate (CaSO4 · 2H2O), is a kind of important renewable gypsum resources. Unlike the natural gypsum, however, phosphorus, fluorine, organic matter and other harmful impurities in phosphogypsum limit its practical use. To ascertain the existence form, content and phase distribution of trace fluoride in phosphogypsum has important theoretical values in removing trace fluoride effectively. In this present paper, the main existence form and phase distribution of trace fluoride in phosphogypsum was investigated by the combination of X-ray photoelectron spectroscopy (XPS) and Electron microprobe analysis (EMPA). The results show that trace fluoride phase mainly includes NaF, KF, CaF2, K2SiF6, Na2SiF6, Na3AlF6, K3AlF6, AlF3 · 3H2O, AlF2.3(OH)0.7 · H2O, Ca5(PO4)3F, Ca10(PO4)6F2. Among them, 4.83% of fluorine exists in the form of fluoride (NaF, KF, CaF2); Accordingly, 8.43% in the form of fluoride phosphate (Ca5(PO4)3F, Ca10(PO4)6F2); 12.21% in the form of fluorine aluminate (Na3AlF6, K3AlF6); 41.52% in the form of fluorosilicate (K2SiF6, Na2SiF6); 33.02% in the form of aluminum fluoride with crystal water (AlF3 · 3H2O, AlF2.3(OH)0.7 · H2O). In the analysis of phase constitution for trace elements in solid samples, the method of combining XPS and EMPA has more advantages. This study also provides theoretical basis for the removal of trace fluorine impurity and the effective recovery of fluorine resources.

On-line double isotope dilution laser ablation inductively coupled plasma mass spectrometry for the quantitative analysis of solid materials

We report on the determination of trace elements in solid samples by the combination of on-line double isotope dilution and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The proposed method requires the sequential analysis of the sample and a certified natural abundance standard by on-line IDMS using the same isotopically-enriched spike solution. In this way, the mass fraction of the analyte in the sample can be directly referred to the certified standard so the previous characterization of the spike solution is not required. To validate the procedure, Sr, Rb and Pb were determined in certified reference materials with different matrices, including silicate glasses (SRM 610, 612 and 614) and powdered samples (PACS-2, SRM 2710a, SRM 1944, SRM 2702 and SRM 2780). The analysis of powdered samples was carried out both by the preparation of pressed pellets and by lithium borate fusion. Experimental results for the analysis of powdered samples were in agreement with the certified values for all materials. Relative standard deviations in the range of 6–21% for pressed pellets and 3–21% for fused solids were obtained from n=3 independent measurements. Minimal sample preparation, data treatment and consumption of the isotopically-enriched isotopes are the main advantages of the method over previously reported approaches.

Determinations of Rare Earth Element Abundance and U-Pb Age of Zircons Using Multispot Laser Ablation-Inductively Coupled Plasma Mass Spectrometry

We have developed a new calibration technique for multielement determination and U-Pb dating of zircon samples using laser ablation-inductively coupled plasma mass spectrometry (ICPMS) coupled with galvanometric optics. With the galvanometric optics, laser ablation of two or more sample materials could be achieved in very short time intervals (~10 ms). The resulting sample aerosols released from different ablation pits or different solid samples were mixed and homogenized within the sample cell and then transported into the ICP ion source. Multiple spot laser ablation enables spiking of analytes or internal standard elements directly into the solid samples, and therefore the standard addition calibration method can be applied for the determination of trace elements in solid samples. In this study, we have measured the rare earth element (REE) abundances of two zircon samples (Nancy 91500 and Prešovice) based on the standard addition technique, using a direct spiking of analytes through a multispot laser ablation of the glass standard material (NIST SRM612). The resulting REE abundance data show good agreement with previously reported values within analytical uncertainties achieved in this study (10% for most elements). Our experiments demonstrated that nonspectroscopic interferences on 14 REEs could be significantly reduced by the standard addition technique employed here. Another advantage of galvanometric devices is the accumulation of sample aerosol released from multiple spots. In this study we have measured the U-Pb age of a zircon sample (LMR) using an accumulation of sample aerosols released from 10 separate ablation pits of low diameters (~8 μm). The resulting (238)U-(206)Pb age data for the LMR zircons was 369 ± 64 Ma, which is in good agreement with previously reported age data (367.6 ± 1.5 Ma). (1) The data obtained here clearly demonstrate that the multiple spot laser ablation-ICPMS technique can become a powerful approach for elemental and isotopic ratio measurements in solid materials.

Correcting sensitivity drift during long-term multi-element signal measurements by solid sampling-ETV-ICP-MS

Solid sampling-electrothermal vaporisation-inductively coupled plasma-mass spectrometry (SS-ETV-ICP-MS) is an attractive technique for the direct simultaneous determination of trace elements in solid samples and especially in long-term studies (i.e. assessment of the homogeneity of reference materials). However, during these studies a downward drift in the instrument sensitivity has been observed due likely to deposits on the sampling and skimmer cones and on the ion lens of the mass spectrometer. Accordingly, in this paper, several means of correcting and/or suppressing sensitivity drift are proposed and evaluated for the monitoring of Cd, Cu, Hg, Mn, Pb, Sb, Se, Sn, Tl, U and V in different reference materials of inorganic and organic (biological) origin. From that studies, the combination of the use of the argon dimer as internal standard together with a modification in the ETV-ICP connection tube seems to be the best mean of getting stable sensitivity during at least 60 consecutive ETV runs.

Determination of trace elements bound to soil and sediment fractions (IUPAC Technical Report)

Abstract This paper presents an overview of methods for chemical speciation analysis of elements in samples of sediments and soils. The sequential leaching procedure is thoroughly discussed, and examples of different applications are shown. Despite some drawbacks, the sequential extraction method can provide a valuable tool to distinguish among trace element fractions of different solubility related to mineralogical phases. The understanding of the speciation of trace elements in solid samples is still rather unsatisfactory because the appropriate techniques are only operationally defined. The essential importance of proper sampling protocols is highlighted, since the sampling error cannot be estimated and corrected by standards. The Community Bureau of Reference (BCR) protocols for sediment and soil give a good basis for most of the solid samples, and the results can be compared among different laboratories.

Electrothermal vaporisation ICP-mass spectrometry (ETV-ICP-MS) for the determination and speciation of trace elements in solid samples - A review of real-life applications from the author's lab.

The use of electrothermal vaporisation (ETV) from a graphite furnace as a means of sample introduction in inductively coupled plasma mass spectrometry (ICP-MS) permits the direct analysis of solid samples. A multi-step furnace temperature programme is used to separate the vaporisation of the target element(s) and of the matrix components from one another. Sometimes, a chemical modifier is used to enable a higher thermal pre-treatment temperature, by avoiding premature analyte losses (stabilisation) or promoting the selective volatilisation of matrix components. In almost all instances, accurate results can be obtained via external calibration or single standard addition using an aqueous standard solution. Absolute limits of detection are typically ~1 pg, which corresponds to 1 ng/g for a typical sample mass of 1 mg. Real-life applications carried out in the author's lab are used to illustrate the utility of this approach. These applications aim at trace element determination in industrial and environmental materials. The industrial materials analysed include different types of plastics - Carilon, polyethylene, poly(ethyleneterephtalate) and polyamide - and photo- and thermographic materials. As samples from environmental origin, plant material, animal tissue and sediments were investigated. Some applications aimed at a multi-element determination, while in other, the content of a single, but often challenging, element (e.g., Si or S) had to be measured. ETV-ICP-MS was also used in elemental speciation studies. Separation of Se-containing proteins was accomplished using polyacrylamide gel electrophoresis (PAGE). Subsequent quantification of the Se content in the protein spots was carried out using ETV-ICP-MS. As the volatilisation of methylmercury and inorganic mercury could be separated from one another with respect to time, no chromatographic or electrophoretic separation procedure was required, but ETV-ICP-MS as such sufficed for Hg speciation in fish tissue.

Direct determination of cadmium in solids using a capacitively coupled microwave plasma atomic emission spectrometer

A capacitively coupled microwave plasma (CMP) operating at 800 W was examined for the direct determination of cadmium in solids. The laboratory-constructed system contained a tungsten cup electrode capable of holding microsample quantities. A low-powered plasma was used to heat the sample, while at higher powers the plasma was used for sample vaporization and excitation. This plasma enabled thermal vaporization (TV) sample introduction to be accomplished in situ as the plasma formed directly around the sample. Thus, the need for sample preparation, procedural steps and sample transport was eliminated. This technique was capable of the direct determination of trace elements in solid samples in less than 5 min. The effects of experimental parameters such as gas flow rate, atomization power and electrode position were investigated. Detection limits obtained for Cd by TV-CMP-AES were in the picogram range with a relative standard deviation of <20%. The accuracy and precision of the method were also evaluated by measuring Cd in several NIST Standard Reference Materials.

Helium Radiofrequency Atomization and Excitation Source(He-RFAES) for Simultaneous Direct Determination of Trace Elements in Solid Samples.

A radiofrequency Ar discharge lamp with a hot electrode, radiofrequency atomization/excitation source (R-FAES) , has been developed for direct determinations of trace elements in solid samples by atomic emission spectrometry In this work, a He RFAES was developed to attain higher excitation temperatures. Among the advantages of the RFAES is the capability of direct simultaneous determinations of elements including halogens in solid samples. At the center of a stainless-steel cylinder, a tantalum cup loaded with a small size sample (5-10 μl or mg) was located and served as a discharge electrode. When an r.f. He plasma was formed between the tantalum cup and the grounded cylindrical enclosure under a reduced pressure, the cup was con-currently heated to a high temperature, owing to the r.f. power dissipation. As a consequence, the sample loaded in the cup was atomized and excited in the He plasma. Compared with graphite, tantalum was effec-tive to attain higher cup temperatures (>2300°C). Basic characteristics and analytical performance were evaluated with standard solutions. The RFAES was successfully applied to simultaneous direct determina-tions of elements including Cl in a NIST standard reference material of biological matrix, SRM 1571 Orchard Leaves.

Trace analysis of ceramic surfaces by laser ionization mass spectrometry

Laser ionization mass spectrometry (LIMS) is an analytical method for the simultaneous determination of concentrations of trace elements in solid samples and for the analysis of layers with thicknesses >1 μm. This laser-induced surface analytical method is limited by the laser focus and crater depth of the laser system applied. Results of mass spectrometric trace analysis on a silicon carbide surface, ZrO2 and high-Tc superconducting ceramics are discussed.

Sample Preparation Techniques—An Important Part in Trace Element Analysis for Environmental Research and Monitoring

Abstract For the determination of minute amounts of elements in environmental samples combined analytical procedures are frequently employed. The combination of suitable sample preparation techniques with adequate detection methods lead to powerful analytical procedures. Decomposition methods are an important part of combined procedures for the determination of trace elements in solid samples. After a short summary of the potential sources for systematic errors two new decomposition methods are described that are suitable for the ashing of organic environmental samples. In one method the organic sample is ashed in a high-frequency excited oxygen plasma. The second method is a high pressure decomposition that permits mineralization of the sample in sealed quartz vessels with nitric acid at temperatures up to 320°C. For both methods the ratio of sample weight to decomposition reagents is comparatively high. This makes these methods in combination with adequate detection methods suitable for the determinatio...

Convenient method for the determination of trace elements in solid samples using an inductively coupled plasma

A method for the determination of trace elements in solid samples is described. The sample is loaded into a graphite cup, which is inserted horizontally into the tail region of the inductively coupled plasma. Application of the method to carrier distillation analysis of impurities in uranium oxide shows that detection limits in the range 0.02–5 µg g–1 with a relative standard deviation of 4–12% are obtainable.

Atomabsorptionsspektrometrie durch Laserverdampfung mit nachfolgender elektrothermischer Atomisierung

The determination of trace elements in solid samples by the combination of laser-evaporation and flameless AAS is used. A ruby laser with passive Q-switch vaporizes microamounts of solids in a chamber. The solid aerosol is transported by an Ar gas flow into a hot graphite furnace, where the solid particles are atomized for the AA-measurement. The influence of the parameters of the laser and the flow rate of Ar is exemplified by a silver determination. Several problems connected with the use of standard powders in laser-AAS are discussed. The vaporization of solids by the laser is the reason for the poor standard deviation of the absorbance values. The analytical results reported here were obtained by the standard addition-technique.