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.

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%.

scholarly journals Quantification of plasma remdesivir and its metabolite GS-441524 using liquid chromatography coupled to tandem mass spectrometry. Application to a Covid-19 treated patient

2020 ◽  
Vol 58 (9) ◽  
pp. 1461-1468 ◽  
Author(s):  
Jean-Claude Alvarez ◽  
Pierre Moine ◽  
Isabelle Etting ◽  
Djillali Annane ◽  
Islam Amine Larabi
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Half Life ◽  
Limit Of Detection ◽  
Treated Patient ◽  
Internal Standard ◽  
Therapeutic Drug ◽  
Active Metabolites ◽  
Limit Of Quantification ◽  
Positive Mode

AbstractObjectivesA method based on liquid chromatography coupled to triple quadrupole mass spectrometry detection using 50 µL of plasma was developed and fully validated for quantification of remdesivir and its active metabolites GS-441524.MethodsA simple protein precipitation was carried out using 75 µL of methanol containing the internal standard (IS) remdesivir-13C6 and 5 µL ZnSO4 1 M. After separation on Kinetex® 2.6 µm Polar C18 100A LC column (100 × 2.1 mm i.d.), both compounds were detected by a mass spectrometer with electrospray ionization in positive mode. The ion transitions used were m/z 603.3 → m/z 200.0 and m/z 229.0 for remdesivir, m/z 292.2 → m/z 173.1 and m/z 147.1 for GS-441524 and m/z 609.3 → m/z 206.0 for remdesivir-13C6.ResultsCalibration curves were linear in the 1–5000 μg/L range for remdesivir and 5–2500 for GS-441524, with limit of detection set at 0.5 and 2 μg/L and limit of quantification at 1 and 5 μg/L, respectively. Precisions evaluated at 2.5, 400 and 4000 μg/L for remdesivir and 12.5, 125, 2000 μg/L for GS-441524 were lower than 14.7% and accuracy was in the [89.6–110.2%] range. A slight matrix effect was observed, compensated by IS. Higher stability of remdesivir and metabolite was observed on NaF-plasma. After 200 mg IV single administration, remdesivir concentration decrease rapidly with a half-life less than 1 h while GS-441524 appeared rapidly and decreased slowly until H24 with a half-life around 12 h.ConclusionsThis method would be useful for therapeutic drug monitoring of these compounds in Covid-19 pandemic.

THE IDENTIFICATION AND HALF LIVES OF FISSION-PRODUCT Rb92 AND Rb93

1960 ◽  
Vol 38 (12) ◽  
pp. 1614-1622 ◽  
Author(s):  
K. Fritze ◽  
T. J. Kennett
Keyword(s):  
Fission Product ◽  
Decay Rate ◽  
Half Life ◽  
Fission Products ◽  
Strontium Isotopes ◽  
A Value ◽  
Γ Ray ◽  
Rubidium Isotopes

The existence of two new rubidium isotopes, Rb92 and Rb93, has been established and their half lives measured. The half lives of these short-lived fission products were determined using a technique of timed precipitations. The values obtained for Rb92 and Rb93 were 5.3 ± 0.5 sec and 5.6 ± 0.5 sec respectively. The half lives of the strontium and yttrium daughters were also determined. The strontium isotopes were studied by observing the decay rate of a characteristic γ-ray peak. For Sr92, the decay of the 1.37-Mev line gave a value of 2.71 ± 0.02 hr. A γ-ray peak at 590 kev, which was found to be associated with Sr93, decayed with a half life of 7.54 ± 0.06 min. The half lives of the yttrium daughters were determined by β counting. The values found for Y92 and Y93 were 3.53 ± 0.02 hr and 10.1 ± 0.1 hr respectively.

Direct visualization of a vast cortical calcium compartment in Paramecium by secondary ion mass spectrometry (SIMS) microscopy: possible involvement in exocytosis

1995 ◽  
Vol 108 (5) ◽  
pp. 1895-1909 ◽  
Author(s):  
N. Stelly ◽  
S. Halpern ◽  
G. Nicolas ◽  
P. Fragu ◽  
A. Adoutte
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Membrane Vesicles ◽  
Cell Periphery ◽  
A Value ◽  
External Reference ◽  
Ion Mass Spectrometry ◽  
First Time ◽  
Secondary Ion

The plasma membrane of ciliates is underlaid by a vast continuous array of membrane vesicles known as cortical alveoli. Previous work had shown that a purified fraction of these vesicles actively pumps calcium, suggesting that alveoli may constitute a calcium-storage compartment. Here we provide direct confirmation of this hypothesis using in situ visualization of total cell calcium on sections of cryofixed and cryosubstituted cells analyzed by SIMS (secondary ion mass spectrometry) microscopy a method never previously applied to protists. A narrow, continuous, Ca-emitting zone located all along the cell periphery was observed on sections including the cortex. In contrast, Na and K were evenly distributed throughout the cell. Various controls confirmed that emission was from the alveoli, in particular, the emitting zone was still seen in mutants totally lacking trichocysts, the large exocytotic organelles docked at the cell surface, indicating that they make no major direct contribution to the emission. Calcium concentration within alveoli was quantified for the first time in SIMS microscopy using an external reference and was found to be in the range of 3 to 5 mM, a value similar to that for sarcoplasmic reticulum. After massive induction of trichocyst discharge, this concentration was found to decrease by about 50%, suggesting that the alveoli are the main source of the calcium involved in exocytosis.

Pharmacokinetics, Pharmacodynamics and Tolerability of a Potent, Non-peptidic, GP IIb/IIIa Receptor Antagonist following Multiple Oral Administrations of a Prodrug Form

1998 ◽  
Vol 79 (01) ◽  
pp. 169-176 ◽  
Author(s):  
Nishit Modi ◽  
Sherron Bullens ◽  
Cheryl Pater ◽  
Michael Lipari ◽  
Kirk Robarge ◽  
...  
Keyword(s):  
Half Life ◽  
Rhesus Monkeys ◽  
Ex Vivo ◽  
Active Form ◽  
Plasma Concentrations ◽  
Volume Of Distribution ◽  
A Value ◽  
Terminal Half Life ◽  
The Right

SummaryRo 44-3888 is a potent and selective antagonist of GP IIb/IIIa. Following IV administration to rhesus monkeys, the (mean ± SD.) clear ance, volume of distribution and terminal half-life of Ro 44-3888 were 4.4 ± 1.8 ml/min/kg, 0.8 ± 0.4 l/kg and 2.5 ± 0.8 h respectively. Oral administration of Ro 48-3657 (1 mg/kg), a doubly protected prodrug form, produced peak concentrations of Ro 44-3888 (152 ± 51 ng/ml), 4.2 ± 2.2 h after dosing. Terminal half-life and estimated bioavailabil ity were 5.1 ± 1.6 h and 33 ± 6% respectively. No effect on blood pressure, heart rate or platelet counts were seen. Adenosine diphosohate (ADP) induced platelet aggregation (PA) and cutaneous bleeding times (CBT) were determined prior to and after the last of 8 daily oral administrations of Ro 48-3657 (0.25 or 0.5 mg/kg) to eight rhesus monkeys. Peak and trough plasma concentrations were proportional to dose and steady state was achieved after the second administration. Inhibition of PA and prolongation of CBT were concentration dependent. The ex vivo IC50 (82 nM) for ADP-mediated PA correlated with a value (58 nM) determined in vitro. The CBT response curve was displaced to the right of the PA curve. CBT was prolonged to ≥25 min when levels of Ro 44-3888 exceeded 190 nM and PA was >90% inhibited. Therefore, in rhesus monkeys, Ro 48-3657 is reproducibly absorbed and converted to its active form, is well tolerated, and has a concentration-dependent effect on PA and CBT. These properties make Ro 48-3657 an attractive candidate for evaluation in patients at high risk for arterial thrombosis.

The Half-life of 130Te Double β-decay

1966 ◽  
Vol 21 (1-2) ◽  
pp. 84-90 ◽  
Author(s):  
N. Takaoka ◽  
K. Ogata
Keyword(s):  
Half Life ◽  
High Sensitivity ◽  
General Tendency ◽  
Β Decay ◽  
A Value ◽  
Three Samples ◽  
Isotopic Analyses ◽  
Isotopic Abundances ◽  
Double Β Decay ◽  
Small Excess

In order to determine the half-life of the 130Te double β-decay, the amounts and isotopic composition of xenon extracted from tellurium ores, from the Oya gold mine in Japan, have been measured with a high-sensitivity mass spectrometer. Compared with atmospheric xenon an excess was definitely found at mass numbers 129, 130 and 131 in the extracted xenon. The excess of 130Xe is predominant, the average amount in three samples being (1.32 ± 0.09) × 10-11 ccSTP/g 130Te. Attributing the excess 130Xe to the double β-decay of 130Te, the half-life is estimated to be (8.20 ± 0.64) × 1020 years, assuming an age of (9.06 ± 0.29) × 107 years for the Te ores. The latter value is the K-Ar age of porphyrite, which is in close geological connection with the Te ores.In order to investigate the other excesses than that of 130Xe, isotopic analyses were also carried out on Xe from three other Te ores from the same mine. The ratios (129Xe/131Xe) excess=1.58 and (129Xe/130Xe) excess = 2.1 were found to be the same for all samples. The origin of these excesses is discussed.In addition a small excess of 128Xe was found. If this is attributed to 128Te double β-decay, the half-life of 128Te is estimated to be 3 × 1022 years, a value shorter by about three orders of magnitude than the theoretically expected half-life. The above estimated half-life may be a lower limit of the 128Te half-life.The general tendency of the isotopic abundances (except for the above excesses), of the xenon extracted from Te ores seems to be to slightly increase in excess as one moves toward the lighter isotopes (as compared with atmospheric xenon).

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.

METABOLISM OF [14C]NORGESTREL IN MAN

1968 ◽  
Vol 42 (4) ◽  
pp. 591-598 ◽  
Author(s):  
P. LITTLETON ◽  
K. FOTHERBY ◽  
K. J. DENNIS
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Thin Layer ◽  
Half Life ◽  
Human Subjects ◽  
Gas Liquid Chromatography ◽  
Apparent Difference ◽  
Enzymic Hydrolysis ◽  
Acidic Compounds ◽  
Related Compounds

SUMMARY [14C]Norgestrel was administered to seven human subjects and 43% of dose was excreted in the urine within 5 days; the biological half-life of the radioactivity was 24 hr. Enzymic hydrolysis released only 32% of the the urinary radioactivity and a further 25% was excreted as sulphate conjugates. The metabolites excreted in the urine were much less polar than those following the administration of the related compounds, norethisterone or lynestrenol. The 3αOH,5β and 3βOH,5β isomers of the tetrahydronorgestrel (13β-ethyl-17α-ethynyl-5β-gonane-3α,17β-diol) were isolated from urine and identified by mass spectrometry and thin-layer and gas—liquid chromatography. Plasma radioactivity decreased more rapidly than after the administration of norethisterone and lynestrenol. About 2% of the administered dose was converted to acidic compounds. There was no apparent difference in the rate of excretion of radioactivity or in the metabolites after either oral or intravenous administration of norgestrel.

Severe isopropanolemia without acetonemia or clinical manifestations of isopropanol intoxication

1993 ◽  
Vol 39 (9) ◽  
pp. 1922-1925 ◽  
Author(s):  
K M Chan ◽  
E T Wong ◽  
W S Matthews
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Serum Concentration ◽  
Half Life ◽  
Clinical Manifestations ◽  
Gas Chromatography Mass Spectrometry ◽  
Toxicological Analysis ◽  
Chromatography Mass Spectrometry ◽  
Osmolal Gap

Abstract This is the first reported case of severe isopropanolemia in a patient who did not experience associated clinical manifestations and acetonemia. The patient was found lying face down in a hotel lobby but at admission was alert and oriented to place and person. Toxicological analysis of the patient's serum revealed the presence of isopropanol at a concentration of 72 mmol/L. An increased serum osmolal gap (81 mOsm/kg) was also observed. The serum concentration of isopropanol decreased to 9.5 mmol/L 15.5 h after admission with an estimated half-life of elimination of 5-7 h. No serum acetone was detected throughout the patient's hospitalization. The identity of isopropanol was confirmed by gas chromatography/mass spectrometry. The patient remained awake and alert while in the hospital and was discharged 5 days after admission. These unusual findings raise some fundamental questions about the role of isopropanol conversion to acetone in the manifestation of symptoms usually associated with isopropanol intoxication.

Sign in / Sign up

Export Citation Format

Share Document