Poly-isotopic elements

For isotope diiution of bl-lsotopic and poly-isotopic elements the equation is the... 

For poly-isotopic elements like Pd, ID constitutes a further option for quantification. For ID, an isotope enriched spike is added to the sample, allowing the determination of the analyte content by measuring the isotope ratio of the spiked sample. One of the key features of the method is that the result is unaffected by instrumental signal drifts or analyte losses occurring after ID. Since total or reproducible analyte recovery is often problematic in trace and ultra trace analysis, ID is well suited for this task, especially if extensive sample pretreatment is employed (Heumann 2004). 

In isotope dilution analysis, a sample with an unknown concentration of the target element, usually in its natural isotopic composition, is mixed and chemically equilibrated with a known amount of an isotope-enriched spike compound of the corresponding element. This approach self-evidently requires the element to be determined to have at least two isotopes measurable by ICP-MS. For poly-isotopic elements, such as lead with four stable isotopes, only two isotopes need to... 

In non-nuclear teehniques, isotopes of the same element generally eaimot be distinguished, while in nuclear techniques, specific isotopes are measured instead of elements. Therefore, direct quantitative information on the associated elements ean be obtained since poly-isotopic elements have eonstant isotope ratios. Further, isotopes of a given element may be diseriminated therefore, analytieal information may be obtained by using elements enrlehed In respeet to a partieular stable isotope or labelled with a radioisotope, e.g. in isotope dilution analysis. In addition to analytical information, isotope studies may also yield kinetie and mechanistic information. 

We will now see that this is equally valid for IDMS of bi-isotopic elements (Eq. 4 and Fig. 2) and in the poly-isotopic case (Eq. 5 and Fig. 3). We note that R can be chosen 2 ways the major isotope abundance being in the denominator or in the nominator of Rx or Ry. We arbitrarily choose the latter, hence Ry 1 and quite different from Rb ( 1). We note that Ry is then little affected by Rb- Also because Ry appears in both nominator and denominator of Eq. 4, any uncertainty on Ry, will have very little effect on the uncertainty of Wx/A/y. On the other hand Rx will be small (the major isotope abundance will now be in the denominator of Rx) with respect to Rb or to 1, so any uncertainty on Rx will not contribute to the uncertainty of A/x/Wy. Consequently only the uncertainty of Rb in the denominator will largely determine the uncertainty of N /Ny and hence of the IDMS result. The precision with which an isotope dilution ratio can be measured, determines the precision of an IDMS determination as far as the isotopic measurement is concerned. Further limitations are, or may be ... 

The other major springboard for the fluorocarbon chemical industry was the "Manhattan Project to develop the atomic bomb. This required the large-scale production of highly corrosive elemental fluorine and uranium(VI) fluoride for the separation of the radioactive 235U isotope. Oils capable of resisting these materials were needed to lubricate pumps and compressors, and polymers were needed to provide seals. Peril uorinated alkanes and polymers such as PTFE and poly(chlorotrifluoroethylene) (PCTFE) proved to have the appropriate properties so practical processes had to be developed for production in the quantities required. In 1947 much of this work was declassified and was published in an extensive series of papers3 which described the fundamental chemistry on which the commercial development of various fluoro-organic products, especially fine chemicals, was subsequently based. 

Barbieri M, Peccerillo A, Poli G, Tolomeo L (1988) Major, trace element and Sr isotopic composition of lavas from Vico volcano (Central Italy) and their evolution in an open system. Contrib Mineral Petrol 99 485-497... 

Why docs an isotope pattern reappear in the product ion spectrum of the m/z 302 parent (Fig. 19, middle panel) The elemental composition of the parent is now Ci4Hi3NOF Cli The m/z 271 species shows no poly-... 

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