[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Espinosa 684 stated that the presence of zinc

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Espinosa [684] stated that the presence of zinc dithiophosphate is the basis for differentiating between automotive and locomotive oils. In environmental
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Methodological Developments and Applications 721 protection studies he applied XRF techniques to the determination of Zn originating from this additive in various kinds of oils. Comparing fresh oils the presence of Zn, Ca, P and S was detected by means of XFR method [692]. Although the spectra obtained manifested to be generally similar, the peak intensities differed slightly in fact. The calculated sets of peak integral ratios: S/Zn, Ca/Zn were in general systematically dif- ferent for the studied oil samples. It was found that the elemental analysis providing information on the additives is complementary to IR spectroscopy in differentiating among oil samples. Freitag [685] reported on the application of TXRF to the determination of trace elements in lubricating oils. It is useful for analysis of wear particles that occur only in amounts of the order of micrograms – such quantities being sufficient for complete analysis. When comparing analytical results and inferring about the similarity of examined oil samples, it is necessary to use some statistical methods. Ob- served differences are small and only application of statistical analysis in the evaluation of obtained results allows us to decide whether they are caused by real differences in the chemical composition of these samples or by random errors. However, this requires many repetitions of measurements for each sam- ple, which in practice can be a problem due to the large overall number of measurements necessary. Lloyd [687] and Siegel [689] applied with success synchrotron X-ray fluo- rescence to differentiation between petroleum products. The XRF method is also used in the analysis of other heavy products of the petroleum industry, e.g. oils, greases, and bituminous masses, detected in the form of blots visible to the naked eye on the clothing of car accident victims or persons suspected of starting fires. Glass Microtraces Glass fragments are known to transfer to the clothing of a person breaking a window. These fragments may be used as evidence, associating the breaker with the crime. Traces in the form of glass fragments are also revealed in cases of traffic accidents, fights or robberies. Fragments of the glass have various sizes. Those found at the scene of the event are larger fragments, whereas those revealed on the clothing, hair or body of persons are small – with linear dimension less than 1 mm. Routine examination of glass fragments encompasses establishing their elemental composition and determining some physical properties, such as the refractive index and density. These data can be used by a forensic scientist for comparison of samples of glass, and also for ascertaining the kind of object they could have been broken off from, hence, establishing their origin.
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