Method For Multielement Analysis Research Articles

Isotachophoretic separation behavior of rare-earth EDTA chelates and analysis of minor rare-earth elements in an iron ore by bidirectional isotachophoresis–particle-induced X-ray emission

Mobilities of 16 anions of rare-earth–EDTA 1:1 chelate (RE–EDTAs) were isotachophoretically measured by using two leading electrolytes (pH 3.6 and 6.0) in order to assess their separation behavior. The leading electrolyte was 20 m M hydrochloric acid. The pH of the solution was adjusted to 3.6 by adding β-alanine and to 6.0 by adding histidine. The obtained mobilities were very close to each other in the range 20.1·10 −5–21.9·10 −5 cm 2 V −1 s −1 with the minimum mobilities for Pr–EDTA and Nd–EDTA for pH 3.6 and 6.0, respectively, and pH dependence was hardly observed. On the basis of the above knowledge, minor rare-earth elements in a standard iron ore sample were determined as RE–EDTAs by bidirectional isotachophoresis–particle-induced X-ray emission (PIXE), where the Fe(II) matrix digested by alkali fusion was separated as Fe(II)Phen 3 2+ (phen=1,10-phenanthroline). Since 5% of the total iron was still detected as Fe(III)EDTA − and might disturb PIXE analysis of RE–EDTA −, itaconic acid was used as the spacer for Fe(III)EDTA − and RE–EDTA −. The fractions of RE–EDTA − were successfully analyzed off-line by a multielemental analytical method, PIXE [analytical result (3.62% (w/w) as RE 2O 3]; the nominal value was 3.37% (w/w) as RE x O y .

Determination of trace iron by electrothemal vaporization/ low-pressure helium ICP-MS.

Although ICP-MS offers a powerful multielement analytical method, the argon gas severely interferes with the determination of iron because of the formation of large background spectra. A combined method of electrothermal vaporization (ETV) and low-pressure helium-ICP-MS was therefore employed to overcome this problem. Mass spectral interferences, however, still occurred at m/z of 54 and 56, which were assigned to 40Ar14N+ and 40Ar16O+, respectively. We found that the polyatomic interferences were caused by leaks of the ambient air through the glass ETV chamber. In the present work, the chamber was newly designed and constructed from aluminum with specially prepared vacuum parts. A 5 μl volume of the sample was placed on a tungsten filament and heated at 2.6 A for 100 s to remove the solvent. After evacuating the chamber to 5 torr, the filament was heated to 2500°C by the discharge of a high-capacity condenser (0.27 F) for evaporating the sample. The resulting plume was transported to the plasma torch with a stream of carrier gas for the determination of the most abundant isotope, 56Fe+. The relative standard deviation for the signal intensity (50 pg of Fe, n = 9) was approximately 13%. The detection limit based on 3σ was 0.8 ng ml-1, which was 25-times lower compared with the conventional argon ICP-MS.

Precise Determination of Trace Elements in Geological Samples by ICP-MS Using Compromise Conditions and Fine Matrix-Matching Strategy

A simple method for multi-element analysis of geological samples has been developed. In this work, compromise conditions involving optimizing the operating parameters of the ICP, adjustment of ion optics voltages and selection of internal standards were carefully investigated. Matrix trace element-matching procedures were employed, in which the external calibration solutions were prepared by dividing the elements of interest into seven groups of different concentration levels according to their average contents of 20 typical standard reference rock samples. The proposed method offered simple procedure of sample preparation, instrument calibration, improved precision and reasonable element coverage. Detection limits ranged from 0.003 - 0.1 µg g-1 for heavier mass elements to 0.01 - 1 µg g-1 for lighter mass elements. Precision was near 1.1 - 10% RSD (lighter mass elements) and 2.0 - 8.0% RSD (heavier mass elements), respectively, with the exceptions of tungsten, molybdenum and thorium. Good agreement between certified and found values were achieved for standard reference rock samples AGV-1, BHVO-2 and GSR-3. Analytical data for rare earth elements were in conformity with values from the chondrite normalized curve.

Laser Ablation Inductively Coupled Plasma Mass Spectrometry for Determination of Trace Elements in Geological Glasses

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used as a powerful multielement analytical method for trace analysis of geological glasses which are useful as reference materials for geochemical in-situ microanalytical work. The quantification of the analytical results was carried out using the BCR-2G and NIST 612 glass standard reference material (SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most of the elements, with increasing mass an increasing of relative sensitivity coefficients was observed. The relative standard deviation (RSD) for determination of trace element concentration of most elements (N=3) are between 2 and 10%. The determination of trace elements in various geological glasses by LA-ICP-MS yielded a good agreement with the reference values and those results of other trace analytical methods.

Low-pressure helium ICP-MS with a water-cooled plasma torch.

Although ICP mass spectrometry offers a powerful multi element analytical method, the background spectra often interfere with the determination. The detectability for halogens is not adequate because of insufficient ionization. In the present work, a low-pressure helium ICP was studied in order to overcome these problems. A plasma was sustained with a water-cooled torch at 400 800 W forward power with a maximum signal intensity at 500 W. The optimal plasma gas-flow rate and sampling depth were 40 ml min-1 and 17 mm, respectively. The signal intensities of 127I+ were much higher than those of the conventional atmospheric-pressure Ar ICP. Background species (ArN+ and Ar2+) were not observed, which may allow the determination of traces of Se (as 80Se+) as well.

Multi-elemental trace analysis of human serum by double-focusing ICP-MS

A method is described for the determination of a selected range of trace and ultratrace elements in human serum, using a double-focusing ICP-MS instrument (ELEMENT, Finnigan-MAT). Serum samples were diluted 1+4 with ultrapure water and addition of Sc, Ga, Y and Tl as internal standards, to a final concentration of 10 µg L –1 , was used for matrix interference correction. Low and medium resolution scans were performed on the instrument for the analyses, the first scan, at m/Δm=300, for the determination of Rb, Sr, Mo, Cd, Pb and U and the second scan, at m/Δm=3000, for the determination of those elements subject to interference at low resolution: Al, Ca, Cr, Mn, Fe, Co, Cu, Zn and Se. A SRM, 1598 Inorganic Constituents in Bovine Serum (NIST), was analysed for validation of the multi-element analysis method. Good agreement was achieved between the found levels and the certified values. The method was also applied to the multi-analysis of trace elements in serum samples from healthy subjects and from uraemic patients. Preliminary experiments carried out with both quadrupole and double-focusing ICP-MS instruments proved to be invaluable for the study of spectral and non-spectral interferences in ICP-MS detection.

Incorporation of Surface Topography in the XPS Analysis of Curved or Rough Samples Covered by Thin Multilayers

Approaches are described for the analysis of XPS signals from samples comprising thin conformal coatings on substrates with non-ideal surface topography. In particular, attention is focused on arbitrarily shaped rough or curved substrates. Relations are derived for the relative x-ray photoelectron intensities emitted from various elements in such non-ideal samples. The surface topography of arbitrarily rough samples is analysed by atomic force microscopy to provide a frequency histogram of the local slopes, which is incorporated into a global, multi-element analysis method for interpretation of the observed XPS elemental intensities. An analogous approach is used for the analysis of curved samples. Our algorithms also enable simultaneous analysis of successively coated multilayer structures. When the elemental composition of the individual layers is known, the fit procedure enables determination of the thickness values of single-layer and multilayer coatings. The range of validity of the theory is discussed. © 1997 by John Wiley & Sons, Ltd.

Use of NAA in marine environment and in archaeology in Greece

Neutron activation analysis (NAA) is a very sensitive and accurate multielement analytical method that is widely applied to the investigation of environmental and archaeological problems. The first part of this paper is a review of pollution studies of toxic trace elements in sediments, seawater and marine organisms of Saronikos Gulf, Greece by NAA. The second part of this paper is a review of provenance studies based on minor and trace element research in ancient ceramics, obsidian, flint, limestone, marble and lead by Instrumental NAA, performed at the NCSR Demokritos.

Characterization of a method for multielement analysis of human blood and serum by ICP-MS

Characterization of a method for multielement analysis of human blood and serum by ICP-MS

Characterization of a method for multielement analysis of human blood and serum by ICP-MS

Characterization of a method for multielement analysis of human blood and serum by ICP-MS

Measurement of Trace Metallic Contaminants on Silicon Wafer Surfaces in Native and Dielectric Silicon Oxides by Vapor Phase Decomposition Flow Injection Inductively Coupled Plasma‐Mass Spectrometry

A highly sensitive multielement analytical method known as vapor phase decomposition flow injection inductively coupled plasma‐mass spectrometry (ICP‐MS) was developed and used to measure the concentration of trace metals on silicon wafer surfaces. The method uses hydrogen fluoride vapor to decompose and release metal contaminants from a surface oxide. These trace metals are then collected by scanning a small drop of dilute acid solution throughout the wafer surface. Trace metals in the solution are measured by ICP‐MS using flow injection (FI) sample introduction. Potentially, 60 elements can be measured with detection limits ranging from 108 to 1011 atom/cm2. Typical surface concentrations of trace metals on silicon wafers with native oxides and dielectric oxides were measured and presented.

Passive sorption sampling method with neutron activation analysis seems to offer perspective in atomospheric trace-element investigation

Investigations of trace elements in the atmosphere require the application of highly sensitive multielement analytical methods and methods allowing sampling of contrasting element speciations. Instrumental neutron activation analysis was used to determine 30 element concentrations in samples under investigation. The results of investigating properties of aerosol samples on filters and some aspects of the study of atmospheric trace-element vapor-gas and submicron aerosol phases are presented. A method for investigating the vapor-gas and submicron aerosol phases of atmospheric trace elements by sorption on collectors with neutron activation analysis of exposed collectors is offered.

A rapid preconcentration method for multielement analysis of natural freshwaters

This study describes an inexpensive and rapid preconcentration method which can be applied directly in the field. It is based on coprecipitation with magnesium hydroxide and has been applied for Al, Fe, Mn, Zn, Cu, Ni, V, Cr, Co, Cd, Be, Y, Sc and Yb in freshwaters. The method has been tested using inductively coupled plasma-atomic emission spectrometry (ICP-AES) by adding known amounts of metals to distilled water and natural freshwater. The detection limit for ICP-AES can be enhanced more than two orders of magnitude for Al, Y, Sc, Yb and approximately one order of magnitude for the other tested elements.

Estimation of Sulfur in Grain by X‐Ray Fluorescence Spectrometry and Its Relation to Sulfur and Aniino Acids of Field Crops1

Energy dispersive X‐ray fluorescence spectrometry (EDXRF) is a rapid method of multielement analysis which includes S. Since most S in grain is associated with the S amino acids in protein, a measure of total S concentration might indicate, in part, grain nutritive value. A study was conducted to determine if total S measured by EDXRF was associated with concentration of cystine, cysteine, and methionine of corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] grain. Results showed that total S when determined as a percent of dry weight was positively correlated with S amino acids in the crops investigated. The highest correlation for methionine with S was for wheat (r = 0.913) followed by sorghum (r = 0.893), corn (r = 0.854), and soybean (r = 0.796). Correlations with S were equally as high for cysteine + cystine in these crops. Total S correlated highly with protein levels in sorghum, wheat, and soybean, but not in corn. Sulfur as a percentage of protein was strongly associated with the S amino acids calculated as a percentage of protein in corn, but not in sorghum, wheat or soybean. The N/S ratio was negatively and significantly correlated with S amino acids (percentage of protein) only in corn and soybean. Total S measured by EDXRF and calculated as percent of dry wt appeared to be a reliable indicator of S amino acid content in the crops studied. Total S may be used as an index of S amino acids in grains when crops are being screened for that character in plant breeding programs.

Chemical composition of nucleation and accumulation mode particles collected in Vienna, Austria

Atmospheric aerosol samples were collected by six-stage low pressure impactors in Vienna downtown. Aerosol particles were deposited on aluminum foils in five size fractions in the size range of 0.04–25 μm AD. The concentration of the components Cl −, Br −, NO 3 −, SO 4 2−, Ca, Cu, Fe, Mg, Pb. Sr, Zn and total C was determined by multi-element analytical methods. A comparison of the relative composition of the size fractions containing nucleation mode and accumulation mode particles showed the components derived from traffic emissions (Pb, Br − and C) to be significantly enriched in the nucleation mode size fraction. On the other hand, each of the components Cl −, SO 4 2−,Ca, Cu, Fe, Mg and Sr has a similar relative concentration in the nucleation mode and in the accumulation mode size fraction. For all samples collected on days with prevailing westerly winds a strong negative correlation between wind speed and sulfate particle size as well as sulfate concentration was observed.

Elemental concentrations in airborne particles from welding and metal spraying operations

An accelerator-based arrangement in which facilities using particle-induced X-rays and gamma-rays and scattered particles are included constitutes a very powerful analytical set-up especially when combined with adequate sampling techniques. In this paper, the designs of two major work environment investigations are described. In one of the investigations (in which 3000 multielemental analyses were performed) a thorough characterization of welding aerosols from different welding operations was carried out. In the other investigation (400 analyses), special concern was devoted to metal spraying operations involving chromium and nickel exposure to workers. To exemplify the fact that the PIXE technique is a fast, multielemental analytical method only requiring very small samples, some results are discussed.

Monostandard activation analysis: Evaluation of the method and its accuracy

The different approaches of the monostandard activation analysis are evaluated critically in order to put them into a common formulation. The nuclear data relevant to the method, which are selected and verified by experiment, are presented for general application. The accuracy of the method for multielement analysis is discussed by comparing the analytical results of the various reference materials from different methods and laboratories with those from monostandard activation analysis.