scholarly journals Absolute and relative measurement of the 243Am half-life

2020 ◽  
Vol 326 (3) ◽  
pp. 1785-1793 ◽  
Author(s):  
M. Marouli ◽  
S. Pommé ◽  
V. Jobbágy ◽  
H. Stroh ◽  
R. Van Ammel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Alpha Particle ◽  
Half Life ◽  
Specific Activity ◽  
Isotope Dilution Mass Spectrometry ◽  
Standard Uncertainty ◽  
Mass Content ◽  
A Value ◽  
Activity Measurements ◽  
Relative Standard

AbstractThe half-life of 243Am has been measured by an absolute and a relative method, i.e. by determining the specific activity of 243Am and the specific activity ratio with 241Am. A mixed 241,243Am reference material was produced and certified for its americium mass content and its isotope amount ratios. The characterisation of the mass content of 243Am was established by isotope dilution mass spectrometry using an 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by thermal ionisation mass spectrometry. Activity measurements were performed by alpha-particle counting at a defined solid angle, as well as high-resolution alpha-particle spectrometry. From the 243Am/241Am activity and isotopic amount ratios, a value of 16.988 (24) was derived for the 243Am/241Am half-life ratio. Using a value of 432.6 (6) a for the 241Am half-life, the corresponding 243Am half-life value, 7349 (15) a, is in good agreement with the result obtained from the absolute method, 7342 (14) a. The mean value, 7345 (14) a, agrees well with data from literature and lowers the relative standard uncertainty to 0.2%.

Half-Life Determination of 41Ca and Some Other Radioisotopes

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 436-446 ◽  
Author(s):  
Walter Kutschera ◽  
Irshad Ahmad ◽  
Michael Paul
Keyword(s):  
Mass Spectrometry ◽  
Electron Capture ◽  
Half Life ◽  
Specific Activity ◽  
Low Energy ◽  
X Rays ◽  
Weighted Mean ◽  
Electron Capture Decay

We have performed a new determination of the half-life of 41Ca by measuring the specific activity of an enriched Ca material with known 41Ca abundance. We measured the activity via the 3.3-keV X-rays emitted in the electron capture decay of 41Ca, and the 41Ca abundance was measured by low-energy mass spectrometry. The result, t1/2 = (1.01 ± 0.10) × 105 yr, agrees with the recent ‘geological’ half-life of Klein et al., (1991), t1/2 = (1.03 ± 0.07) × 105 yr, and with the corrected value of Mabuchi et al. (1974), t1/2 = (1.13 ± 0.12) × 105 yr. We recommend the weighted mean of these three measurements, t1/2 = (1.04 ± 0.05) × 105 yr, as the most probable half-life of 41Ca. We also discuss the situation of the radioisotopes, 32Si, 44Ti, 79Se and 126Sn, whose half-lives, though still uncertain, are potentially interesting for future AMS studies and other applications.

The half life of plutonium-240 determined by specific-activity measurements

1984 ◽  
Vol 35 (3) ◽  
pp. 171-172 ◽  
Author(s):  
Frederick J. Steinkruger ◽  
George M. Matlack ◽  
Richard J. Beckman
Keyword(s):  
Half Life ◽  
Specific Activity ◽  
Activity Measurements

THE HALF-LIFE OF RUBIDIUM-87

1966 ◽  
Vol 44 (12) ◽  
pp. 3033-3038 ◽  
Author(s):  
C. C. McMullen ◽  
K. Fritze ◽  
R. H. Tomlinson
Keyword(s):  
Mass Spectrometry ◽  
Half Life ◽  
A Value

The quantity of 87Sr produced from the decay of 87Rb during an accurately known period of time has been determined. The analysis of the 87Rb and the 87Sr content of four different rubidium samples was performed by mass spectrometry. A value of (4.72 ± 0.04) × 1010 years was calculated from the results of the measurements for the half-life of 87Rb.

The half life of 239Pu: By specific activity measurements and by mass spectronetric determination of daughter growth

1978 ◽  
Vol 29 (8) ◽  
pp. 505-507 ◽  
Author(s):  
A.H. Jaffey ◽  
H. Diamond ◽  
W.C. Bentley ◽  
K.F. Flynn ◽  
D.J. Rokop ◽  
...  
Keyword(s):  
Half Life ◽  
Specific Activity ◽  
Activity Measurements

A redetermination of the half-life of239Pu by specific activity measurements

1981 ◽  
Vol 64 (1-2) ◽  
pp. 181-193 ◽  
Author(s):  
D. Brown ◽  
K. M. Glover ◽  
M. King ◽  
G. Phillips ◽  
F. J. G. Rogers ◽  
...  
Keyword(s):  
Half Life ◽  
Specific Activity ◽  
Activity Measurements

scholarly journals Need for speed: evaluation of dilute and shoot-mass spectrometry for accelerated metabolic phenotyping in bioprocess development

2021 ◽  
Author(s):  
Alexander Reiter ◽  
Laura Herbst ◽  
Wolfgang Wiechert ◽  
Marco Oldiges
Keyword(s):  
Mass Spectrometry ◽  
Matrix Effects ◽  
Isotope Dilution Mass Spectrometry ◽  
Random Mutagenesis ◽  
Product Formation ◽  
Small Scale ◽  
Limited Information ◽  
Bioprocess Development ◽  
Response Factors ◽  
Relative Standard

AbstractWith the utilization of small-scale and highly parallelized cultivation platforms embedded in laboratory robotics, microbial phenotyping and bioprocess development have been substantially accelerated, thus generating a bottleneck in bioanalytical bioprocess sample analytics. While microscale cultivation platforms allow the monitoring of typical process parameters, only limited information about product and by-product formation is provided without comprehensive analytics. The use of liquid chromatography mass spectrometry can provide such a comprehensive and quantitative insight, but is often limited by analysis runtime and throughput. In this study, we developed and evaluated six methods for amino acid quantification based on two strong cation exchanger columns and a dilute and shoot approach in hyphenation with either a triple-quadrupole or a quadrupole time-of-flight mass spectrometer. Isotope dilution mass spectrometry with 13C15N labeled amino acids was used to correct for matrix effects. The versatility of the methods for metabolite profiling studies of microbial cultivation supernatants is confirmed by a detailed method validation study. The methods using chromatography columns showed a linear range of approx. 4 orders of magnitude, sufficient response factors, and low quantification limits (7–443 nM) for single analytes. Overall, relative standard deviation was comparable for all analytes, with < 8% and < 11% for unbuffered and buffered media, respectively. The dilute and shoot methods with an analysis time of 1 min provided similar performance but showed a factor of up to 35 times higher throughput. The performance and applicability of the dilute and shoot method are demonstrated using a library of Corynebacterium glutamicum strains producing l-histidine, obtained from random mutagenesis, which were cultivated in a microscale cultivation platform. Graphical abstract

A New Method for Plasminogen Standardization

1968 ◽  
Vol 20 (03/04) ◽  
pp. 548-554
Author(s):  
J Gajewski ◽  
G Markus
Keyword(s):  
Proteolytic Activity ◽  
Specific Activity ◽  
Molar Ratio ◽  
Sharp Transition ◽  
Equivalence Point ◽  
Constant Amount ◽  
Residual Level ◽  
Activity Measurements ◽  
Complete Saturation ◽  
Human Plasminogen

SummaryA method for the standardization of human plasminogen is proposed, based on the stoichiometric interaction between plasminogen and streptokinase, resulting in inhibition of proteolytic activity. Activation of a constant amount of plasminogen with increasing amounts of streptokinase yields linearly decreasing activities, as a function of streptokinase, with a sharp transition to a constant residual level. The point of transition corresponds to complete saturation of plasmin with streptokinase in a 1:1 molar ratio, and is therefore a measure of the amount of plasminogen present initially, in terms of streptokinase equivalents. The equivalence point is independent of the kind of protein substrate used, buffer, pH, length of digestion and, within limits, temperature. The method, therefore, is not subject to the variations commonly encountered in the usual determination based on specific activity measurements.

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