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The selenium determination in biological materials by the classical fluorometric method (FM) is time-consuming and also hazardous, as it requires the destruction of the organic matrix samples with hot HNO3/HClO4 mixtures prior to analysis. Accordingly, commercial analytical laboratories are increasingly using faster instrumental methods; for sample digestion, avoid using HClO4. Because of these procedural changes, the results obtained by commercial laboratories may be unreliable, especially for samples containing Se in organic forms. One such "difficult" substrate is Se yeast, which contains most of its Se as selenomethionine. To establish which methods for Se analysis and sample digestion are applicable, samples of Se yeast and of selenomethionine standards were sent to laboratories employing either flame atomic absorption spectrometry (FAAS), inductively coupled plasma-mass spectrometry (ICP-MS), or hydride generation atomic absorption spectrometry (HGAAS). The results were compared with those obtained by FM and non-destructive instrumental neutron activation analysis (INAA). ICP-MS, after microwave digestion of sample with HNO3/H2O2, produced results within 5% of the expected values, as did those obtained by FM and INAA. With FAAS, acceptable results were obtained after digestion with HNO3/HCl. With HGAAS, sample digestion with HNO3/H2O2 produced values that were systematically elevated by about 10% and exhibited standard deviations of > or = 10%. Thus, current methods of sample digestion are applicable for Se yeast analysis by ICP-MS and FAAS, but not by HGAAS.
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PMID:Evaluation of methods for total selenium determination in yeast. 1229 28

A new method for the determination of ultra-trace level of lanthanides such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Yb and Lu in human rib is explored. Closed-vessel microwave digestion with concentrated HNO3 is used for the sample preparation and the digested analyte is directly analyzed by ICP-MS. The method is sensitive and accurate and, is efficient for the determination of the fourteen lanthanides listed above. Detection limit for various elements ranges from 0.0007 microgram/L to 0.005 microgram/L. Calibration plots exhibit good linearity with high linear correlation coefficient r > or = 0.997. Recoveries of spiked samples ranges from 93.7% to 115.4%. Precision is < 3% RSD. Rhodium is used as the internal standard to compensate the signal suppression caused by the sample matrix. Isobaric overlap of polyatomic ions caused by matrix oxide/hydroxide of barium is corrected by interference correction factor. Two standard reference materials, namely "Human Hair GBW07601" and "Wheat Flour GBW08503" are used for quality control of the analyzed samples.
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PMID:[Application of microwave dissolution and inductively coupled plasma-MS spectrometry for determination of ultra-trace level of lanthanides in human rib]. 1260 26

In the event of a nuclear incident it is essential that analytical information on the distribution and level of contamination is available. An ICP-MS method is described which can provide data on plutonium contamination in food within 3 h of sample receipt without compromising detection limits or accuracy relative to traditional counting methods. The method can also provide simultaneous determinations of americium and neptunium. Samples were prepared by HNO3 closed-vessel microwave digestion, evaporated to dryness and diluted into a mobile phase comprising 1.5 M HNO3 and 0.1 mM 2,6-pyridinedicarboxylic acid. A commercially available polystyrene-divinylbenzene ion chromatography column provides on-line separation of 239Pu and 238U reducing the impact of the 238U1H interference. Oxidation of the sample using H2O2 ensures all Pu is in the Pu(+4) state. The oxidation also displaces Np away from the solvent front by changing the oxidation state from Np(+3) to Np(+4) and produces the insoluble Am(+4) ion. Simultaneous Pu, Am and Np analyses therefore require omission of the oxidation stage and some loss of Pu data quality. Analyses were performed using a magnetic sector ICP-MS (Finnigan MAT Element). The sample is introduced to the plasma via an ultrasonic nebuliser-desolvation unit (Cetac USN 6000AT+). This combination achieves an instrumental sensitivity of 238U > 2 x 10(7) cps/ppb and removes hydrogen from the sample gas, which also inhibits the formation of 238U1H. The net effect of the improved sample introduction conditions is to achieve detection levels for Pu of 0.020 pg g(-1) (4.6 x 10(-2) Bq kg(-1)) which is significantly below 1/10th of the most stringent EU (European Union) legislation, currently 0.436 pg g(-1) (1 Bq kg(-1)) set for baby food. The new method was evaluated with a range of biological samples ranging from cabbage to milk and meat. Recovery of Pu agrees with published values (100% +/- 20%).
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PMID:A rapid and accurate method for the determination of plutonium in food using magnetic sector ICP-MS with an ultra-sonic nebuliser and ion chromatography. 1261 74

Trace impurities in lead-tin solders were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES) for the forensic discrimination of solder samples from different origins by a comparison of the concentration for each element. After about 10 mg of sample was accurately measured and taken into a glass tube, 1 ml of HNO3 was added. The tube was capped and heated at 80 degrees C for 10 min. After cooling to the room temperature, 1 ml of HCl and 2 ml of purified water were added. It was then agitated until the sample was completely dissolved, followed by dilution to 10 ml. Five elements (Sb, Bi, Cu, As and Ag) in this solution were determined by ICP-AES. The observed values for these elements in the NIST Standard Reference Material 1131 showed good agreement with the certified ones. Eighteen kinds of solder samples could be distinguished from each other, since all of the pairs among these samples provided remarkable difference in the concentration of the trace elements. The copper concentration should have been excluded from the comparison when it increased after melting by a soldering iron made of copper.
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PMID:Forensic discrimination of lead-tin solder based on the trace impurity analysis by ICP-AES. 1267 51

Different techniques have been employed in order to evaluate the most efficient procedure for the extraction of selenium from soil as required for speciation. Selenium contaminated sediments from Stewart Lake Wetland, California were used. A strong acid mineralization of the samples gives quantitative total selenium, which is then used to estimate recoveries for the milder extraction methods. The different extraction methodologies involve the sequential use of water, buffer (phosphate, pH 7) and either acid solution (e.g. HNO3 or HCl) or basic solutions (e.g. ammonium acetate, NaOH or TMAH). Pyrophosphate extraction was also evaluated and showed that selenium was not associated with humic acids. The extractants were subsequently analyzed by size exclusion chromatography (SEC) with UV (254 and 400 nm) and on-line ICP-MS detection; anion exchange chromatography, and ion-pair reversed phase chromatography with ICP-MS detection. For sequential extractions the extraction efficiencies showed that the basic extractions were more efficient than the acidic. The difference between the acidic and the basic extraction efficiency is carried to the sulfite extraction, suggesting that whatever is not extracted by the acid is subsequently extracted by the sulfite. The species identified with the different chromatographies were selenate, selenite, elemental selenium and some organic selenium.
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PMID:Sequential extractions of selenium soils from Stewart Lake: total selenium and speciation measurements with ICP-MS detection. 1283 87

In the present work a method for simultaneous metals determination, in urban air particulate matter by ICP-AES has been set up. A large number of elements (18) has been analyzed, including major (Al, Fe, K, and Mg), minor (Na, Pb and Zn) and trace (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Sb, Sr and V) elements. The procedure consists of microwave sample acidic total digestion by HNO3/HF mixture and subsequent analysis by ICP-AES, using different assemblies depending on sample treatment procedure: a quartz Meinhard nebulizer/cyclonic chamber, if HF excess was eliminated, or a cross-flow nebulizer/plastic Scott chamber, suitable for application with HF. A cyclonic chamber for hydride generation was used for As, Sb and Hg determination. The procedure was tested with Standard Reference Materials 1648 NIST Urban Particulate Matter and Certified Reference Material No8 NIES "Vehicle Exhaust Particulates". Two sampling supports, quartz fibre and polycarbonate filters, have been examined in order to find the most suitable i.e. the one characterized by less interference. Some real samples of urban air particulate matter, TSP, PM10 and PM2.5 fractions, collected during an intercomparison campaign promoted by Regione Lombardia, have been analyzed with the procedure developed.
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PMID:Optimization of an urban particulate matter multi-element analysis method by inductively coupled plasma--atomic emission spectrometry (ICP-AES). 1291 Nov 46

This article introduced a method for the determination of total quantity of rare earths, Ca, Mg, Mn and Fe in rare-earths-magnesium with ICP-AES. The total quantity of rare-earths was calculated by the quantum of cerium, the measurement channel of cerium was fixed by the method of Offset Profile Add Lines, by changing the entrance slit angle, based on the fixed channels of the ICP-AES. The sample was melted with HNO3, HF, HClO4 and HCl, the difficulty of melting sample was properly settled. The method of internal standard was used in the determination, cobalt elected for the internal standard, and the same concentration cobalt liquor was added in the sample liquor. This article made the measurement parameters test, for example the quantum of pump, the height of observation, etc, and examined the liner range, accuracy, background equal concentration, detection limits and precision. The results showed that the method was simpler than chemical analytic method in operating, and could simultaneously determined many kinds of elements. It was compared with chemical method, the results were satisfactory.
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PMID:[Determination of total quantity of rare earths, Ca, Mg, Mn and Fe in rare-earths-magnesium by ICP-AES with offset profile add lines]. 1293 44

In this paper, the decomposition method of sulfur and the determination of trace arsenic in sulfur by GFAAS with La(NO3)3-Ni(NO3)2 matrix modifier were studied in detail. The decomposition of sulfur with mixed acid HNO3-HClO4 by controlled temperature electrothermal method or pressure crucible method was efficient and safe. The sensitivity of the determination of arsenic with La(NO3)3-Ni(NO3)2 matrix modifier was higher than with Ni(NO3)2 or Mg(NO3)2 matrix modifiers. The detection limit was 0.034 microgram.mL-1 (k = 3). The analytical results of the sulfur samples were coincident with the results of determination by HG-ICP-AES. The adding recoveries were 97.5%-110% and the relative standard deviation was less than or equal to 2.1% (n = 4).
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PMID:[Determination of trace arsenic in sulfur by graphite furnace atomic absorption spectrometry with La(NO3)3-Ni(NO3)2 matrix modifier]. 1294 52

A new method is described for the analysis of whole coal for the major ash forming elements by ICP-AES. The major ash forming elements were extracted with HF and HNO3 in an ultrasonic water bathe. The best proportion of the acid and the time of extraction were studied. Compared with the ash content of coal, the extraction ratio is more than 95%. Recovery ratio is between 96%-104%. RSD of extraction and determination is less than 4% (n = 9).
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PMID:[Acid extraction of coal for the determination of major ash forming elements by ICP-AES]. 1294 63

A method for the determination of trace tin in aluminum alloy by ICP-AES is proposed. The sample is dissolved in the acid mixture of HCl, HNO3, and a little HF is added dropwise. By fuming with sulfuric acid, the sample is then dissolved in HCl media for the determination of tin. Two sensitive wavelengths of tin in ultra-violet region are selected as analytical lines. The results are in accordance with spectrophotometric and FAAS methods, and a standard reference material of aluminum alloy is also analyzed with satisfactory results. The method is simple, rapid and sensitive, It can be used for the determination of trace tin in aluminum alloys.
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PMID:[Determination of trace tin in aluminum alloy by ICP-AES]. 1295 53


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