Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Iron Isotopes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1999

Iron isotope biosignatures.

The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.

Earth, Planet↗
PubMed2004

[Application of double focusing magnetic sector high resolution ICP-MS to the study of iron stable isotope trace].

Iron absorption efficiency study is one of the key steps to overcome iron deficiency anemia. Determination of iron isotope ratios is the base of iron absorption study. For this purpose radioactive isotope trace method, neutron activation, and thermal ionization mass spectrometry etc. have been used as accessory means. A double focusing inductively coupled plasma mass spectrometry (DF-ICP-MS) was used to determine isotope ratios of Fe in food and human faeces in this paper. Interferences of 40Ar16O to 56Fe and 40Ar14N to 54Fe were avoided by using higher resolution (3000). Longer times and fast electronic scanning were employed to decrease the influence of signal fluctuations from the plasma. Instrumental parameters of the mass spectrometer were optimized while keeping the total integral time under 27s. RSD values obtained for isotope ratios of 5Fe/56Fe, 57Fe/56Fe and 58 Fe/56Fe were 0.23%, 0.14%, 0.22%, respectively, for a natural standard solution of 5 microg x mL(-1). The method has been used to iron nutrition studies.

Iron↗
PubMed1995

Determination of iron absorption using erythrocyte iron incorporation of two stable isotopes of iron (57Fe and 58Fe) in very low birthweight premature infants.

Due to limited erythropoiesis, iron needs for the premature infant during the first 2 months of life are low. With the potential for increased use of erythropoietin in the preterm infant, iron requirements may become markedly higher. The ability of the preterm infant to absorb iron, therefore, becomes crucial. Previous studies using single stable isotopes of iron without metabolic balances were unable to quantitatively determine iron absorption since the percentage of absorbed iron appearing in the erythrocyte could not be measured. The objective of the current study was to determine iron absorption using the method of erythrocyte iron incorporation of two stable isotopes of iron given by the enteral and parenteral route to very low birth weight (VLBW) infants. Results obtained were compared to iron absorption values from studies using single isotopes and metabolic balance techniques. Six VLBW premature infants (gestational age 26.8 +/- 1.7 weeks, postnatal age 3.6 +/- 1.9 weeks, birth weight 863 +/- 117 g) were studied. Iron dosages were (i.v.) 0.15 mg/kg (57FeSO4) and (enteral) 1.5 mg/kg (58FeSO4). Erythrocyte isotope ratios, 57Fe/54Fe and 58Fe/54Fe, were determined by inductively coupled plasma mass spectrometry (ICP/MS) from single blood samples (100 microliters) collected before and after concurrent enteral (58Fe) and parenteral (57Fe) administration of isotopes. Only 17.8% of the i.v.-infused iron dose was incorporated into hemoglobin on day 15. Using a correction factor based on the percentage of i.v. iron (57Fe) incorporated into erythrocytes, the corrected incorporation of 58Fe was calculated to be 26.3 +/- 13.0% of the enteral dose of 58FeSO4.

Absorption↗
PubMed1979

A method for the detection and assay of iron stable isotope tracers in blood serum.

Methodology for use of stable isotopes of iron (54Fe, 57Fe, and 58Fe) as biological tracers was developed. Tracers were quantitated by measurement of ion abundances with a quadrupole mass spectrometer. The volatility of the iron was enhanced by chelation with 2,4-pentanedione prior to analysis. Samples were introduced into the mass spectrometer via a direct inlet probe. Ion abundance ratios were calculated from integrated ion current measurements obtained for selected ions in the two-ligand fragment of the chelate. Stable isotope tracer concentrations were calculated from these ratios. A prodecure was developed for the formation and purification of serum iron chelates. The method was used to analyze iron standards and blood serum samples containing known amounts of added 58Fe. The disappearance from pony serum of injected 58Fe was used as an in vivo test of the method. It was estimated that a minimum of 1.5 mg of either 54Fe, 57Fe, or 58Fe would be required to label 1 g of natural iron at detectable levels. The methods has promise as an alternative to radioisotope tracer techniques for some applications involving human subjects.

Animals↗
PubMed2005

Coupled Fe(II)-Fe(III) electron and atom exchange as a mechanism for Fe isotope fractionation during dissimilatory iron oxide reduction.

Microbial dissimilatory iron reduction (DIR) is an important pathway for carbon oxidation in anoxic sediments, and iron isotopes may distinguish between iron produced by DIR and other sources of aqueous Fe(II). Previous studies have shown that aqueous Fe(II) produced during the earliest stages of DIR has delta56Fe values that are 0.5-2.0%o lowerthan the initial Fe(III) substrate. The new experiments reported here suggest that this fractionation is controlled by coupled electron and Fe atom exchange between Fe(II) and Fe(III) at iron oxide surfaces. In hematite and goethite reduction experiments with Geobacter sulfurreducens, the 56Fe/54Fe isotopic fractionation between aqueous Fe(II) and the outermost layers of Fe(III) on the oxide surface is approximately -3%o and can be explained by equilibrium Fe isotope partitioning between reactive Fe(II) and Fe(III) pools that coexist during DIR. The results indicate that sorption of Fe(II) to Fe(III) substrates cannot account for production of low-delta56Fe values for aqueous Fe(II) during DIR.

Adsorption↗
PubMed1994

Absorption of non-haem iron from food during normal pregnancy.

OBJECTIVE: To determine whether the increased iron demands of pregnancy could be met by increased absorption from dietary sources. DESIGN AND SETTING: Longitudinal prospective study in the research unit of a maternity hospital. SUBJECTS: 12 normal pregnant women. INTERVENTIONS: At 12, 24, and 36 weeks' gestation (within one week) and 16-24 weeks after delivery women ate a breakfast of meat, bread, and orange juice (3.2 mg iron), extrinsically labelled with the stable isotope iron-54 (2.8 mg); the stable isotope iron-57 (200 micrograms) was given intravenously. MAIN OUTCOME MEASURES: Serum samples were taken for 10 hours after administration of the isotopes; ratios of the isotopes were measured by inductively coupled plasma mass spectrometry, and the absorption of oral iron was calculated. RESULTS: The geometric mean (95% confidence interval) absorption of iron at 12, 24, and 36 weeks' gestation was 7% (5% to 11%), 36% (28% to 47%), and 66% (57% to 76%) respectively. At 16-24 weeks after delivery the absorption was 11% (6% to 21%). The mean increase in absorption at 36 weeks (compared with that at 12 weeks) was 9.1 times (6.0 to 13.7). One pregnant woman developed iron deficiency anaemia but was otherwise indistinguishable from the others. CONCLUSIONS: An increase in the absorption of iron from food is a physiological consequence of normal pregnancy, not the result of developing anaemia during pregnancy, and such an increase is large enough to meet the increased requirements of pregnancy provided that the dietary intake is adequate.

Female↗
PubMed1986

Erythrocyte incorporation of ingested stable isotope of iron (58Fe).

Because of a possible hazard from the use of radioisotopes to determine iron absorption by infants, the use of stable isotopes for this purpose has much appeal. We have applied the method of inductively coupled plasma mass spectrometry (ICP/MS) to determine the mass ratio, 58Fe/57Fe, in blood before and after oral administration of 58Fe. From the increase in erythrocyte enrichment with 58Fe, we have calculated percentage absorption of iron. We have shown that the coefficient of variation of measured mass isotope ratio is 0.1-1.0%, depending on the conditions of the measurement. The method has been applied to a feasibility study involving four infants. Each infant was given 58Fe either as a single dose or as one dose on each of two consecutive days. Each dose provided 1.945 mg iron and 1.440 mg 58Fe. Samples of blood were obtained before isotope administration and at 14, 42, and 60 days thereafter. Isotopic analysis of the samples demonstrates that this approach results in a sufficiently large isotope enrichment to permit satisfactory measurement of iron availability. It is concluded that this new method is highly promising for studies of iron availability in infants and children.

Absorption↗
PubMed2001

Isotopic homogeneity of iron in the early solar nebula.

The chemical and isotopic homogeneity of the early solar nebula, and the processes producing fractionation during its evolution, are central issues of cosmochemistry. Studies of the relative abundance variations of three or more isotopes of an element can in principle determine if the initial reservoir of material was a homogeneous mixture or if it contained several distinct sources of precursor material. For example, widespread anomalies observed in the oxygen isotopes of meteorites have been interpreted as resulting from the mixing of a solid phase that was enriched in 16O with a gas phase in which 16O was depleted, or as an isotopic 'memory' of Galactic evolution. In either case, these anomalies are regarded as strong evidence that the early solar nebula was not initially homogeneous. Here we present measurements of the relative abundances of three iron isotopes in meteoritic and terrestrial samples. We show that significant variations of iron isotopes exist in both terrestrial and extraterrestrial materials. But when plotted in a three-isotope diagram, all of the data for these Solar System materials fall on a single mass-fractionation line, showing that homogenization of iron isotopes occurred in the solar nebula before both planetesimal accretion and chondrule formation.

Journal Article↗
PubMed1978

Absorption of stable isotopes of iron, copper, and zinc during oral contraceptives use.

The absorption of iron, copper, and zinc was determined in 22 women 19 to 25 years of age from the difference between intake and fecal output of the stable isotopes 58Fe, 65Cu, and 70Zn, as measured by neutron activation analysis. Of the 22 women, 14 were using oral contraceptive agents, and the other eight were not. Absorption in the group using oral contraceptive agents did not differ significantly from the group not using oral contraceptive agents. The overall iron absorption averaged 14%, copper 57%, and zinc 38%.

Adult↗