scholarly journals 230Th-234U model ages of some uranium standard reference materials

2011 ◽  
Vol 1 (1) ◽  
pp. 31-35 ◽  
Author(s):  
R. W. Williams ◽  
A. M. Gaffney
Keyword(s):  
Reference Materials ◽  
Closed System ◽  
Half Life ◽  
Certified Reference Materials ◽  
Isotope Dilution Mass Spectrometry ◽  
Standard Reference Materials ◽  
National Bureau ◽  
System Behavior ◽  
Icp Ms ◽  
Solid Form

Abstract The “age” of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to a source. The 230Th- 234U chronometer can be used to determine the production date of even very recently-produced material ( 234U half life = 245250 ± 490 years; 230Th half life = 75690 ± 230 years [1]), provided that the 230Th/234U at the time of formation is known, and that there has been no Th-U fractionation in the sample since production. For most samples of uranium, ages determined with this chronometer are “model ages”, because they are based on the assumptions of a) some initial amount of 230Th in the sample, and b) closed-system behavior of the sample since production. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for materials where these assumptions may be tested. The U isotopic standards have known purification and production dates and closed-system behavior in the solid form (U3O8) may be reliably assumed. In addition, these materials are widely available and can serve as informal round-robin inter-laboratory comparison samples. We determined 230Th-234U model ages for seven of these isotopic standards by isotope dilution mass spectrometry using a multi-collector ICP-MS. The standards dated for this study are U005-A, U010, U030-A, U100, U850, U900 and U970. Model ages obtained range from ∼ 30 to ∼ 52 years ago (reference date: 5-May-2009). The model age of U100 is the same as the purification date, within uncertainty. The other six standards analyzed all give model ages older than the purification dates of record. The magnitude of the discrepancy between model age and purification date does not correlate with the model age or the amount of 232Th in the samples. This indicates that excess 230Th in these six standards results from incomplete purification during production.

A Method for the Routine Determination of Methylmercury in Marine Tissue by GC Isotope Dilution-ICP-MS

2012 ◽  
Vol 95 (4) ◽  
pp. 1189-1194 ◽  
Author(s):  
Stig Valdersnes ◽  
Amund Maage ◽  
Daniel Fliegel ◽  
Kåre Julshamn
Keyword(s):  
Reference Material ◽  
Reference Materials ◽  
Isotope Dilution ◽  
Isotope Dilution Mass Spectrometry ◽  
Standard Reference Materials ◽  
Statistical Measures ◽  
Icp Ms ◽  
Wide Range ◽  
Z Scores

Abstract Currently, there is no legal limit for methyl mercury (MeHg) in food; thus, no standardized method for the determination of MeHg in seafood exists within the European jurisdiction. In anticipation of a future legislative limit an inductively coupled plasma isotope dilution mass spectrometry (GC-ICP-ID-MS) method was developed in collaboration with the European Standardization Organization (CEN). The method comprises spiking the tissue sample with Me201Hg, followed by decomposition with tetramethylammonium hydroxide, pH adjustment and derivatization with sodium tetraethylborate, and finally organic extraction of the derivatized MeHg in a hexane phase. Subsequently, the sample is analyzed via GC-ICP-MS and the result calculated using the ID equation. The working range of the method was 0.0005–1.321 mg/kg MeHg in marine tissue, with an internal reproducibility (RSD) of 12–1%. The method was validated based on statistical measures, such as the z-scores, using the commercially available reference materials from National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1566b, NIST SRM 2977 and National Research Council of Canada (NRCC) TORT 2, NRCC, DORM 3, NRCC DOLT 4, and European Reference Material (ERM) CE 464. Z-scores for all standard reference materials, except for NIST SRM 1566b, were better than |1.5|. The wide range of marine tissues used during the validation ensures that the method will be applicable for measuring of MeHg in seafood matrixes of all kinds.

scholarly journals Uranium, thorium, and potassium analyses using pXRF spectrometry

2021 ◽  
Author(s):  
R D Knight ◽  
B A Kjarsgaard ◽  
E G Potter ◽  
A Plourde
Keyword(s):  
Reference Materials ◽  
Certified Reference Materials ◽  
Standard Reference Materials ◽  
Regression Equations ◽  
Exponential Relationship ◽  
Icp Ms ◽  
Total Digestion ◽  
Correction Curve ◽  
High Concentrations ◽  
Digestion Methods

The application of portable XRF spectrometry (pXRF) for determining concentrations of uranium (U), thorium (Th) and potassium (K) was evaluated using a combination of 12 Certified Reference Materials, 17 Standard Reference Materials, and 25 rock samples collected from areas of known U occurrences or mineralization. Samples were analysed by pXRF in Soil, Mining Cu/Zn and Mining Ta/Hf modes. Resulting pXRF data were compared to published recommended values, obtained by total or near total digestion methods with ICP-MS and ICP-OES analysis. Results for pXRF show a linear relationship, for thorium, potassium, and uranium (<5000 ppm U) as compared to the recommended concentrations. However, above 5000 ppm U, pXRF results show an exponential relationship with under reporting of pXRF concentrations compared to recommended values. Accuracy of the data can be improved by post-analysis correction using linear regression equations for potassium and thorium, and samples with <5000 ppm uranium; an exponential correction curve is required at >5000 ppm U. In addition, pXRF analyses of samples with high concentrations of uranium (e.g. >1 wt.% U) significantly over-estimated potassium contents as compared to the published values, indicating interference between the two elements not calibrated by the manufacturer software.

Elemental concentrations in the National Bureau of Standards' environmental coal and fly ash Standard Reference Materials

1975 ◽  
Vol 47 (7) ◽  
pp. 1102-1109 ◽  
Author(s):  
J. M. Ondov ◽  
W. H. Zoller ◽  
Ilhan. Olmez ◽  
N. K. Aras ◽  
G. E. Gordon ◽  
...  
Keyword(s):  
Fly Ash ◽  
Reference Materials ◽  
Standard Reference Materials ◽  
National Bureau ◽  
Elemental Concentrations

New Standard Reference Materials for X-Ray Powder Diffraction

1982 ◽  
Vol 26 ◽  
pp. 45-51
Author(s):  
Camden R. Hubbard
Keyword(s):  
Reference Materials ◽  
Nuclear Power ◽  
Standard Reference Materials ◽  
Measurement Technology ◽  
National Bureau ◽  
State Governments ◽  
X Ray ◽  
Ferrous Metals ◽  
Research Organizations ◽  
Improve Measurement

Standard Reference Materials (SRMs) from the National Bureau of Standards are samples or artifacts certified for one or more particular parameters. The NBS has produced SRHs since 1905 to aid commerce, to improve measurement technology and to assist in the enforcement of regulations. Today nearly 900 different SRHs are available to serve major segments of industry such as ferrous metals, nonferrous metals, mining, glass, primary chemicals, computer, nuclear power and electronics. In addition to the industrial customers, major SRM users include both federal and state governments, universities and nonprofit research organizations.

Measurement and Standard Reference Materials in Clinical Chemistry

1968 ◽  
Vol 14 (10) ◽  
pp. 929-943 ◽  
Author(s):  
Donald S Young ◽  
Thomas W Mears
Keyword(s):  
Uric Acid ◽  
Reference Materials ◽  
Measurement System ◽  
High Purity ◽  
Clinical Chemistry ◽  
Standard Reference Materials ◽  
National Bureau ◽  
Additional Component ◽  
Clinical Laboratories ◽  
Chemical Measurements

Abstract The concepts of the measurement system based upon four parameters—length (meter), mass (kilogram), time (second), and temperature (kelvin)—are developed. The proper daily operation of an analytic laboratory depends upon these basic measurements and others derived from them, e.g., the liter. An additional component of chemical measurement which directly influences accuracy is the purity of the standards and reagents employed. The standard reference materials program of the National Bureau of Standards provides a central source of guaranteed high-purity reference materials which are available to all. The reliability of chemical measurements should increase as new standard reference materials such as cholesterol, uric acid, urea, and creatinine are utilized to standardize methods and to calibrate instruments in the clinical laboratories of this country.

X-Ray Powder Diffraction For Studying the Mineralogy of fly ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Gregory I. McCarthy
Keyword(s):  
Fly Ash ◽  
Powder Diffraction ◽  
Reference Materials ◽  
Standard Reference Materials ◽  
National Bureau ◽  
Fly Ashes ◽  
X Ray ◽  
High Calcium

ABSTRACTA brief summary of the use of x-ray powder diffraction for studying the mineralogy of fly ash is presented. Mineralogies of low-, intermediate- and high-calcium fly ashes are discussed and illustrated by results from XRD characterization of U.S. National Bureau of Standards fly ash Standard Reference Materials.

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