Sample destruction analysis

ABSTRACT The aim of this study was to test portable infrared spectroscopy for non-destructive analysis of ancient construction mortar. Mortar samples from the House of the Vestals, in Pompeii, Italy, were initially examined with traditional analytical techniques, including X-ray fluorescence, X-ray diffraction and thin section analysis. These techniques were used to establish mineralogical and chemical profiles of the samples and to verify the results of experimental field methods. Results showed the lime-based binder was composed of calcite, and the volcanic sand aggregate contained clinopyroxene, plagioclase, sanidine and olivine crystals. 

The high sensitivity of modem instrumental techniques such as ICP-MS (Chapter 9) means that in many cases only small samples (typically, a hundred milligrams or less) need be taken for destructive analysis. However, this also means that the amounts of some individual elements may be very low, and problems of contamination can be significant. Common external contaminants include A1 from deodorants, Pb from paint or car exhausts, Zn from skin particles (and therefore from dust), and Na from sweat. The levels of contamination for each batch of samples will be revealed by the sample... 

Williams-Thorpe, O., Potts, P. J., and Webb, P. C. (1999). Field-portable non-destructive analysis of lithic archaeological samples by X-ray fluorescence instrumentation using a mercury iodide detector Comparison with wavelength-dispersive XRF and a case study in British stone axe provenancing. Journal of Archaeological Science 26 215-237. 

Elemental analysis of sample digests Non-destructive analysis of solid samples... 

A number of conclusions may be drawn from this discussion of the destructive analysis of samples. 

Destructive analysis will continue to be necessary, for many types of samples, owing to the nature of certain samples. The complexity of the composition of some samples often imposes use of a separation step prior to the analysis itself. Furthermore, the classical techniques are... 

Destructive analysis is also necessary when there is a need to concentrate the components of a given sample, the components being present at very low concentrations (or in traces), often in a very complex matrix. 

The techniques of destructive analysis involve taking some special precautions concerning the sampling in general, and the dissolution-decomposition process in particular, in order to avoid the risk of contamination. 

There is no such thing as a completely non-destructive analysis. Upon interaction of the beam with the sample, a series of surface-disruption phenomena can occur. This fact is illustrated in Table 14.10 for the four major surface analysis techniques mentioned above. The least surface disruption occurs in ESCA and the measurements are characteristic of the surface. However, when charged particles such as electrons and ions are... 

Collaborative Testing. A second approach to assessing accuracy, when no certified reference material is available, may be used in conjunction with analysis by independent methods and in-house materials. Sample exhanges with other laboratories can help establish the existence or absence of systematic errors in a method. Collaborative tests are most useful in this regard when some of the participating laboratories use different sample preparation and quantification. The utility of independent analysis methods and comparisons between destructive and non-destructive analysis is again emphasized here. 

The JACADS closure activities will involve the dismantling and destruction of that portion of the facility that cannot be decontaminated to meet the 5R cleanliness standard. An area decommissioning matrix delineates the areas that will be decontaminated and dismantled, decontaminated and abandoned in place, or solely abandoned in place (U.S. Army, 2000c). The remaining systems, structures, and components (SSCs) that are left in place must meet the Resource Conservation and Recovery Act (RCRA) criteria for decontamination as well as the Army standard of 5R. Areas that were kept free of any agent or hazardous materials will be sampled to demonstrate their cleanliness in accordance with the final closure sampling and analysis plan. 

In 2006, a table-top energy-dispersive XRF (ED-XRF) spectrometer was acquired by the Archaeometry Lab to facilitate non-destructive analysis of obsidian and other types of artifacts. One of the first projects performed on the new XRF spectrometer was the re-analysis of the geological samples from sources in Peru. As a result, it is now possible for the Archaeometry Lab to use either XRF or NAA to successfully determine the provenance of obsidian artifacts from Peru. Due to its light weight, the spectrometer also has the potential to be transported from the laboratory to museums and to archaeological sites for in situ analysis. 

NIR in the diffuse reflectance mode is a technique that also allows non-destructive analysis of polymers with very little or no sample preparation [80, 81]. NIR is based on measurement of light reflected by the sample when exposed to electromagnetic radiation in the range from 780 nm (12820 cm-1) to 2500 nm (4000 cm-1). Qualitatively this is the region be-... 

Analytical technique Non-destructive analysis possible (conservation of the sample after analysis) Sample quantity required Sample preparation Analysis type Spatial resolution Limit of detection... 

Analysis of a painting is essential if there is any doubt about its provenance, or if there is suspicion that it is not the claimed artist s work. More often analysis is designed to discover the materials the artist used and how he applied them, and to uncover any later additions, as well as to assess the extent of deterioration and identify attempts by previous restorers to rectify them. Chemists have at their disposal several analytical tools. Some are by nature destructive, by which is meant that a sample will be removed and so permanently lost from the painting, but many modem ones are non-destructive like the Raman technique mentioned above. Non-destructive methods of analysis are preferred, and while the term destructive analysis implies permanent damage to a painting this only involves extracting a minute piece that would normally be hidden under the frame, or one that is so tiny that its removal will not be noticed. From such miniscule fragments the modem analytical chemist can deduce an enormous amount of data. 

Comparative studies were performed to evaluate microwave digestion with conventional sample destruction procedures. These included the analysis of shellfish, meats, rocks, and soils. Generally, comparable accuracy at much shorter digestion time was found for the MAE vs the classical digestion method (39). 

A wealth of information on the subject of sample destruction can be found in a comprehensive book on sample preparation for trace element analysis [3]. 

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