Elemental assay

At PicArsn, both thermal and fast NAA were compared for non-destructive gross element assay in selected materials used in ammo (Ref 14), specifically A1 in aluminized high expls (eg, Minols), Cl in AP and Mn in manganese dioxide (as used in pyrotechnic flare compns). 

Analyses performed may include conventional wet chemistry, coupled with atomic absorption spectroscopy or other metal-scan techniques to provide a quantitative elemental assay, plus X-ray diffraction to determine the major crystalline constituents. 

TABLE 10. Elemental Assay, Percent Hydrolysis, and Limiting Viscosity lumber for Partially Hydrolysed Lignin Copolymer -... 

The table in this appendix recommends primary standards for many elements. An elemental assay standard must contain a known amount of the desired element. A matrix matching standard must contain extremely low concentrations of undesired impurities, such as the analyte. If you want to prepare 10 ppm Fe in 10% aqueous NaCl, the NaCl must not contain significant Fe impurity, because the impurity would then have a higher concentration than the deliberately added Fe. 

Precise and accurate trace element assays on coal are extremely difficult and require constant vigilance to avoid errors that can be introduced both in the laboratory and in the coal-handling procedures. In the future this program will extend the present studies to coals from different parts of the country, study additional trace elements in coal such as arsenic, selenium, beryllium, and others, and apply the developed techniques to more power plants. 

Isotope dilution involves isotopes of the same element, thus eliminating differences in chemical behavior that can plague techniques that use different elements for the spike than the one being analyzed. This, along with the fact that quantitative recovery is not necessary once spike and sample have been equilibrated, makes isotope dilution less subject to error arising in chemical processing than many elemental assay techniques, a fact of great importance at low concentration levels. 

The literature on isotope dilution is so voluminous that it is impossible to cover the subject thoroughly in a single chapter. It is in fact tantamount to impossible to locate all relevant papers, let alone read them. There are also questions arising from the definition of inorganic. Elemental assay has traditionally been an inorganic discipline and analysis of, say, body fluids biological. The question is where, for example, to place analysis of lead in human serum. The area into which such analyses fall depends on whether it is the analyte or the sample that is used for the def-... 

For chemical analysis of each sample, approximately 10 g of soil was transferred to a Gooch crucible. Surface debris such as twigs were removed, and the crucibles were heated in a muffle furnace at 500 °C for 24 h to remove organic components. The ashed soil was then pulverized with a pestle in a porcelain mortar. For each soil position, four 0.5-g portions of fine powder were analyzed separately, and the results were averaged. Soil analyses were performed in-house by atomic absorption spectrometry on a Varian Model 1250 spectrophotometer according to our previously reported method, which involves total dissolution of the sample in acid (11,12). The elements assayed were strontium, zinc, magnesium, calcium, sodium, lead, iron, aluminum, manganese, and potassium. 

Hamilton EI, Minski MJ and Cleary JJ (1972/ 1973) Problems concerning multi-element assay in biological materials. Sci Total Environ 1 1 — 14. Hart MM and Adamson RH (1971) Antitumor activity and toxicity of salts of inorganic group 3a... 

A very important observation at this point is that an IDMS assay is in principle a physical measurement since it is a measurement of ratio of isotopes and not of a ratio of elements (as in classical analytical chemistry). Indeed two numbers of atoms are compared in a ratio determination and these atoms belong to the same element. Hence ail the chemical interferences, normal in a chemical assay, do not affect the result anymore. Combined with the fact that the requirement of being quantitative - essential and difficult in classical chemistry assay - must not be fulfilled (after spiking), this means that IDMS ranks higher in the hierarchy of methods than normal elemental assay methods since it is far less subject to potential chemical error sources. In other words its inherent potential for good precision and accuracy (i.e. small overall uncertainty) and - at least as important -the transparency of the uncertainty propagation in (Eqs. 4 and 5) give it the character of what some have called a "reference method" or even a definitive method". 

Elemental assay Muscovite mica, North Carolina Phlogopite mica, Canada Phlogopite mica, Finland... 

In other cases, the subsamples are dissolved in nitric acid in the operators analytical laboratory. An aliquant of each subsample, carrying about 4 mg of plutonium, is taken into a 5 ml penicillin vial and dried carefully to form an adherent film of nitrate salt on the bottom of the vial. The two aliquants are intended for elemental assays. Another fraction of at least one subsample is usually prepared for isotopic analysis and dried as above. With current products issued from high burnup spent fuel, some 20 penicillin vials could be packed together into a single Type A container and flown to SAL. 

Safeguards analytical laboratories use essentially the same sorts of techniques and equipment as research and plant laboratories for nuclear material isotopic and elemental assay and... 

As a result of the industrial use of U, commercially acquired U-containing chemicals or U standard solutions intended for elemental assay purposes will not necessarily have the natural isotopic composition, but will most often be depleted in U [66]. An unnatural isotopic composition may also be encountered for Li in chemicals, as it may be depleted in Li, as a result of its use as LiD as fusion fuel in thermonuclear weapons and in nuclear fusion [67]. 

Finally, in the context of elemental assay via isotope dilution and tracer experiments using stable isotopes, an isotopically enriched spike or tracer is added to a sample wherein the element of interest typically shows the natural isotopic composition. These isotopically enriched spikes are another example of human-made variations. 

Analysis of Reagent Purity this compound can be characterized by elemental assay and H NMR spectroscopy. H NMR (300... 

The levels of the various elements assayed were as follows ... 

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