High precision analyses

Kane JS, Siems DF, Arbogast BF (1992) Geochemical exploration reference samples GXR-r to GXR-4 and GXR-6 evaluation of homogeneity based on high precision analyses. Geostds Newslett 16 45-54. 

From the preceding discussion it should be clear that the level of isotopic fractionation for a major rock-forming element like Mg in an object that was once molten in the early Solar System is a barometer of either total pressure (large F) or partial pressures relative to saturation (small F). In order to use Mg as a cosmobarometer, high-precision analyses of Mg isotope ratios in both chondrules and C AIs are required. 

Oil shale and coal conversion technologies are presently in a stage of rapid development. Analysis of materials involved in these processes is an important part of the investigation of possible environmental and health impacts of the processes. High precision analyses are desirable even in those cases where sampling uncertainties are relatively large, so that the analytical procedures will not add appreciably to the overall error. 

Like terrestrial °Ne/ Ne ratios, it might be expected that Ar/ Ar ratios vary due to different initial sources building the Earth or to early fractionation events. Measurements of MORE and OIB Ar/ Ar ratios typically are atmospheric within error, but have been of low precision due to the low abundance of these isotopes. While some high-precision analyses of MORE and OlE... 

Classical or wet chemistry analysis techniques such as titrimetry and gravimetry remain in use in many laboratories and are still widely taught in Analytical Chemistry courses. They provide excellent introductions to the manipulative and other skills required in analytical work, they are ideal for high-precision analyses, especially when small numbers of samples are involved, and they are sometimes necessary for the analysis of standard materials. However, there is no doubt that most analyses are now performed by instrumental methods. Techniques using absorption and emission spectrometry at various wavelengths, many different electrochemical methods, mass spectrometry, gas and liquid chromatography, and thermal and radiochemical methods, probably account for at least 90% of all current analytical work. There are several reasons for this. 

Accuracy for all thorium measurements by TIMS is limited by the absence of an appropriate normalization isotope ratio for internal correction of instrumental mass fractionation. However, external mass fractionation correction factors may be obtained via analysis of suitable thorium standards, such as the UC-Santa Cruz and IRMM standards (Raptis et al. 1998) for °Th/ Th, and these corrections are usually small but significant (< few %o/amu). For very high precision analysis, the inability to perform an internal mass fractionation correction is probably the major limitation of all of the methods for thorium isotope analysis discussed above. For this reason, MC-ICPMS techniques where various methods for external mass fractionation correction are available, provide improved accuracy and precision for Th isotope determinations (Luo et al. 1997 Pietruszka et al. 2002). 

Norman M, McCulloch M, O Neill H, Brandon A (2004) Magnesium isotopes in the Earth, Moon, Mars, and Pallasite parent body high precision analysis of olivine by laser ablation multi-collector ICPMS. Lunar and Planetary Science Conference XXXV 1447... 

High precision analysis of the multiple rare isotopes of a specific element permit the distinction of different mass-dependent fractionation mechanisms. 

C. Pin, B. Le Fevre, S. Joannon, Isotope dilution and plasma source mass spectrometry An optimal combination for high precision analysis of trace elements. Can. 

At the beginning of the 1990s, two new ionization methods, electrospray ionization (ESI) [9] and matrix-assisted laser desorption/ionization (MALDI) coupled to time-of-flight (TOF) analysers [10] that avoided such inconveniences, were developed and continue to revolutionize the role of mass spectrometry in biological research. These methods allow the high-precision analysis of biomolecules of very high molecular weight. 

For superconductor materials and precursors high-precision analysis is very important. To this aim flame atomic absorption can be applied, provided the precision is optimized, as is possible, for example, by using internal standardization and multichannel spectrometers. It should, however, be remembered that to control the stoichiometric composition, in addition the determination of non-metals such... 

Severinghaus et al. (1998) demonstrated that thermal fractionation of the air in polar fim layers can be detected and separated from the gravitational effect by high precision analysis of and " Ar/ Ar ratios. Rapid temperature changes at the surface induce... 

PS-core particles to the core-shell latices, Fig. 17 also shows the slightly asymmetric size distribution found for rather narrowly distributed latex systems. For a highly precise analysis of the SAXS-data the directly measured distributions should be used instead of the Gaussian distribution often used in the analysis of colloidal particles [47]. 

White,W.M.,Albardde,F.,Tdlouk,P.(2000)High-precision analysis of Pb isotope ratios by multi-collector ICP-MS. Chemical Geology, 167, 257-270. 

The disadvantages of differential reactor are low conversion, requiring accurate and sensitive analysis methods, high-precision analysis instruments otherwise it will be very difficult to ensure data accuracy and repeatability, which often restrict the choice for the differential reactor. 

Chemical analysis of the metal can serve various purposes. For the determination of the metal-alloy composition, a variety of techniques has been used. In the past, wet-chemical analysis was often employed, but the significant size of the sample needed was a primary drawback. Nondestmctive, energy-dispersive x-ray fluorescence spectrometry is often used when no high precision is needed. However, this technique only allows a surface analysis, and significant surface phenomena such as preferential enrichments and depletions, which often occur in objects having a burial history, can cause serious errors. For more precise quantitative analyses samples have to be removed from below the surface to be analyzed by means of atomic absorption (82), spectrographic techniques (78,83), etc. 

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