Atomic spectroscopy analysis

In using atomic spectroscopy analysis the sample introduction is an extension to sample preparation. To understand the limitations of practical sample introduction systems it is necessary to reverse the train of thought, which tends to flow in the direction of sample solution > nebulisation > spray chamber > excitation > atomisation. An introduction procedure must be selected that will result in a rapid breakdown of species in the atomiser to give reproducible results irrespective of the sample matrix. In designing an FI A system to carry out atomic emission and to generate efficient free atom production for excitation the following criteria must be adhered to as closely as possible ... 

Aono M and Souda R 1985 Quantitative surface atomic structure analysis by low energy ion scattering spectroscopy Japan. J. Appl. Phys. Part 1 24 1249-62... 

Chemical Analysis. The presence of siUcones in a sample can be ascertained quaUtatively by burning a small amount of the sample on the tip of a spatula. SiUcones bum with a characteristic sparkly flame and emit a white sooty smoke on combustion. A white ashen residue is often deposited as well. If this residue dissolves and becomes volatile when heated with hydrofluoric acid, it is most likely a siUceous residue (437). Quantitative measurement of total sihcon in a sample is often accompHshed indirectly, by converting the species to siUca or siUcate, followed by deterrnination of the heteropoly blue sihcomolybdate, which absorbs at 800 nm, using atomic spectroscopy or uv spectroscopy (438—443). Pyrolysis gc followed by mass spectroscopic detection of the pyrolysate is a particularly sensitive tool for identifying siUcones (442,443). This technique rehes on the pyrolytic conversion of siUcones to cycHcs, predominantly to [541-05-9] which is readily detected and quantified (eq. 37). 

Naiiow-line uv—vis spectia of free atoms, corresponding to transitions ia the outer electron shells, have long been employed for elemental analysis usiag both atomic absorption (AAS) and emission (AES) spectroscopy (159,160). Atomic spectroscopy is sensitive but destmctive, requiring vaporization and decomposition of the sample iato its constituent elements. Some of these techniques are compared, together with mass spectrometry, ia Table 4 (161,162). 

Analytical Atomic Spectroscopy Surface Analysis," Mnnual Book ofMSTM Standards, part 3.06, American Society for Testing and Matedals, Philadelphia, Pa., 1992. 

Fluorescence spectroscopy Analysis in which the intensity and wavelength of the energy that is emitted from excited atoms is used to indicate the presence of certain compounds. 

M. Cullen (ed.), Atomic Spectroscopy in Elemental Analysis, Blackwell Publishing, Oxford (2003). 

Young, S. M. M. and M. Pollard (2000), Atomic spectroscopy and spectrometry, in Ciliberto, E. and G. Spoto (eds.), Modern Analytical Methods in Art and Archaeology, Chemical Analysis Series, Vol. 155, Wiley, New York, pp. 21-54. 

Determination of trace metals in seawater represents one of the most challenging tasks in chemical analysis because the parts per billion (ppb) or sub-ppb levels of analyte are very susceptible to matrix interference from alkali or alkaline-earth metals and their associated counterions. For instance, the alkali metals tend to affect the atomisation and the ionisation equilibrium process in atomic spectroscopy, and the associated counterions such as the chloride ions might be preferentially adsorbed onto the electrode surface to give some undesirable electrochemical side reactions in voltammetric analysis. Thus, most current methods for seawater analysis employ some kind of analyte preconcentration along with matrix rejection techniques. These preconcentration techniques include coprecipitation, solvent extraction, column adsorption, electrodeposition, and Donnan dialysis. 

Asaro, F., Applied Gamma-Ray Spectrometry and Neutron Activation Analysis, Proceedings of the XX. Colloquium Spec-troscopicum Internationale and 7. International Conference on Atomic Spectroscopy Praha 1977 Invited Lectures II, 413-426. 

W.C. Martin, Sources of Atomic Spectroscopy Data for Astrophysics , in PL. Smith and W. L. Wiese (eds.), Atomic and Molecular Data for Space Astronomy Needs, Analysis and Availability, Springer, Berlin, 1992. 

Fig. 2. Solid-phase arsenic in ppm versus depth in m from a continuous core. The core consists of clayey silt to depth of 28 m, and fine sand thereafter with a silt horizon at 34 m depth. As was measured by digestion with an HCI-HNO3-H2O aqua regia solution followed by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy analysis.

Baudelet M., Boueri M., Yu J., Mao S., Piscitelli V., Mao X., Russo R. 2007. Time-resolved ultraviolet laser-induced breakdown spectroscopy for organic material analysis. Spectrochimica Acta Part B Atomic Spectroscopy, 20,1329-1334. 

Elemental analysis at the trace or ultratrace level can be performed by a number of analytical techniques however, atomic spectroscopy remains... 

Elemental analysis can be performed at ultratrace levels with any atomic spectrometric technique and the final selection is based on the identity and the number of elements to be determined. The initial step that is common to all analyses by atomic spectroscopy is the generation of a homogeneous solution. 

All reagents and solvents that are used to prepare the sample for analysis should be ultrapure to prevent contamination of the sample with impurities. Plastic ware should be avoided since these materials may contain ultratrace elements that can be leached into the analyte solutions. Chemically cleaned glassware is recommended for all sample preparation procedures. Liquid samples can be analyzed directly or after dilution when the concentrations are too high. Remember, all analytical errors are multiplied by dilution factors therefore, using atomic spectroscopy to determine high concentrations of elements may be less accurate than classical gravimetric methods. 

On the basis of the preceding discussion, it should be obvious that ultratrace elemental analysis can be performed without any major problems by atomic spectroscopy. A major disadvantage with elemental analysis is that it does not provide information on element speciation. Speciation has major significance since it can define whether the element can become bioavailable. For example, complexed iron will be metabolized more readily than unbound iron and the measure of total iron in the sample will not discriminate between the available and nonavailable forms. There are many other similar examples and analytical procedures that must be developed which will enable elemental speciation to be performed. Liquid chromatographic procedures (either ion-exchange, ion-pair, liquid-solid, or liquid-liquid chromatography) are the best methods to speciate samples since they can separate solutes on the basis of a number of parameters. Chromatographic separation can be used as part of the sample preparation step and the column effluent can be monitored with atomic spectroscopy. This mode of operation combines the excellent separation characteristics with the element selectivity of atomic spectroscopy. AAS with a flame as the atom reservoir or AES with an inductively coupled plasma have been used successfully to speciate various ultratrace elements. 

Atomic spectroscopy is an excellent method of analysis for trace or ultratrace levels of many elements in the periodic table. The major disadvantage of all atomic spectroscopic methods is that they provide no information on the oxidation state of the element or its speciation. This disadvantage can be redressed by the use of selective reagents coupled... 

R.M. Harrison and S. Raposomanikos, Environmental Analysis using Chromatography Interfaced with Atomic Spectroscopy, Ellis Horwood Series in Analytical Chemistry, Ellis Horwood Ltd., Chichester, 1992. 

Analysis for atoms means that atomic spectroscopy is limited to the elements. In fact, the keyword for atomic spectroscopy is metals. The vast majority of methods involving atomic spectroscopy are methods for determining metals. 

Ruzicka, J. Hansen, E. H. Flow-Injection Analysis, Wiley New York, 1981. Valcarcel, M. Gallego, M. Separation techniques. In Flow Injection Atomic Spectroscopy, Bruguera, J. L. Ed., Marcel Dekker New York, 1989. 

This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atomic spectroscopy suitable to the novice and expert. Although a widely used and accepted method for metal and nonmetal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each chapter will completely cover an area of atomic spectroscopy where rapid development has occurred. 

Environmental Analysis using Chromatography Interfaced with Atomic Spectroscopy, Harrison, R.M., and Rapsomanakis, S., Ellis Horwood, Chichester, 1989. Becoming dated, but still a valuable guide to this specialist area. 

Heavy metal contamination of pH buffers can be removed by passage of the solutions through a Chelex X-100 column. For example when a solution of 0.02M HEPES containing 0.2M KCl (IL, pH 7.5) alone or with calmodulin, is passed through a column of Chelex X-100 (60g) in the K form the level of Ca ions falls to less than 2 x 10 M as shown by atomic absorption spectroscopy. Such solutions should be stored in polyethylene containers that have been washed with boiling deionised water (5min) and rinced several times with deionised water. TES and Tris have been similarly decontaminated from metal ions (see reference on atomic absorption analysis on p 62). 

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