Interference analytical tools

Today, ICP-AES is an indispensable inorganic analytical tool. However, because of the high plasma temperature, ICP-AES suffers from some severe spectral interferences caused by line-rich spectra of concomitant matrix elements such as Fe, Al, Ca, Ni, V, Mo and the rare-earth elements. This is at variance with AAS. The spectral interference can of course be minimised by using a (costly) high-resolution spectrometer. On the other hand, the high temperature of the ICP has the advantage of reducing chemical interferences, which can be a problem in AAS. 

The former phase, external control tool that can be tuned to vary the interference term and hence the reaction outcome. The latter phase, 5(E), serves as an analytical tool that provides a route to the phases of the scattering wavefunctions. 

There are several factors which make neutron activation analysis (NAA) an appropriate technique for investigating potential pollutants in coal and the combustion process. First, the multi-element nature of NAA is useful because of the large number of potential elemental pollutants, such as Se, Hg, As, Zn, Ni, Sb, and Cd. Also, the use of elemental ratios made possible by the multi-element capability facilitates the understanding of chemical behavior during the combustion process. Elemental ratios have been used previously in urban (15) and upper atmospheric (26) studies. Secondly, the sensitivity and selectivity of NAA allows determination of many elements present at very low concentrations (ppm or lower), and the results are unaffected by matrix interferences. This sensitivity also allows analysis of very small samples. Finally, the cost of NAA when conducted as a multi-element analytical tool is competitive with more conventional and less sensitive techniques on the cost-per-element-per-sample basis. 

Fluorescence spectrometry is a powerful analytical tool by virtue of its high sensitivity however, the usual presence of emission and excitation spectral interferences calls for additional sample pretreatments. This technique has been used in combination with SFE mainly in the determination of PAHs, which possess well-known luminescence properties. Screening these compounds from soil entailed the use of a high-pressure flow-cell such as that of Fig. 7.17B and allowed the extraction and determination of five individual PAHs in soil with relative standard deviations less than 5% also, it provided qualitative and semi-quantitative information from the screening of natural soil samples [113]. 

Photoneutrons are produced at considerable flux densities in the heavy metal of the bremsstrahlung converter. For example, in the linear accelerator used by the authors, a thermal neutron flux density of some 10 °cm s has been produced in the tantalum converter during normal operation (30MeV, 150 pA). This appears a relatively poor flux density compared to that of a standard nuclear research reactor. Nevertheless, in advantageous cases trace analyses can be performed. For example, routine analyses of several elements in air-dust samples were carried out by activation with photoneutrons (see below). Normally, however, the photoneutron flux is analytically negligible, whether as an analytical tool or as a source of interference. 

The applications described in this chapter demonstrate the potential of matrix-free laser-induced MS in inorganic chemistry. The minimum sample preparation, the lack of matrix interference in the low mass region, and the variety of simple and complex samples that can be ionized and characterized are some of the attractive features of LDI-MS. Although largely restricted to determination of biomolecules, LDI-MS has the potential of being used as an analytical tool for inorganic samples as well. 

Surface analytical tools Structural information Interference/limitations... 

The mechanical properties of hydraulic mortars are closely associated with the setting process which takes place when such mortars are mixed with water. The progress of this process can be monitored by time-dependent measurements of various properties including mechanical parameters such as tensile stress. Frequently, calibrations are required. Moreover, complications are encountered by invasive procedures. On the contrary, optical methods generally avoid such interferences since mechanical contacts between object and analytical tool do not take place. Measurements which are recorded in absolute units provide a further very important advantage. These conditions are met by LRC. 

A particularly useful analytical tool is the three-isotope plot, which allows one to confirm that measured isotope ratios are free from spectral interference from an... 

Resonance Raman spectroscopy (RRS) leads to increased selectivity in Raman spectral measurements. The Raman spectrum of individual components in a complex mixture can be selectively enhanced by a judicious choice of laser wavelength. Only the Raman bands of the chromophore which is in resonance at the wavelength of excitation are significantly enhanced. Raman bands of non-absorbing species are not enhanced and do not interfere with those of the chromophore. Clearly, resonance Raman is a very sensitive analytical tool capable of providing detailed molecular vibrational information. 

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