Emission spectroscopy, metal analysis

AA, and IR spectroscopy. Metal analysis may be performed by atomic absorption or emission spectroscopy and their stoichiometric amounts in the carbonyl complexes may be determined. Samples may be digested carefully and cautiously with nitric acid in a fume hood before the determination of metal contents. For mass spectrometric determination the carbonyl complex should be dissolved in an organic solvent, injected onto a GC column and identified from the characteristic mass ions. The carbonyl ligands in the complex may be determined by thermal decomposition of the metal carbonyl followed by analysis of carbon monoxide on a GC-TCD. 

Trace-element analysis of metals can give indications of the geographic provenance of the material. Both emission spectroscopy (84) and activation analysis (85) have been used for this purpose. Another tool in provenance studies is the measurement of relative abundances of the lead isotopes (86,87). This technique is not restricted to metals, but can be used on any material that contains lead. Finally, for an object cast around a ceramic core, a sample of the core material can be used for thermoluminescence dating. 

The predorninant method for the analysis of alurninum-base alloys is spark source emission spectroscopy. SoHd metal samples are sparked direcdy, simultaneously eroding the metal surface, vaporizing the metal, and exciting the atomic vapor to emit light ia proportion to the amount of material present. Standard spark emission analytical techniques are described in ASTM ElOl, E607, E1251 and E716 (36). A wide variety of weU-characterized soHd reference materials are available from major aluminum producers for instmment caUbration. 

Rubidium metal is commeicially available in essentially two grades, 99 + % and 99.9 + %. The main impurities ate other alkali metals. Rubidium compounds are available in a variety of grades from 99% to 99.99 + %. Manufacturers and suppliers of mbidium metal and mbidium compounds usually supply a complete certificate of analysis upon request. Analyses of metal impurities in mbidium compounds are determined by atomic absorption or inductive coupled plasma spectroscopy (icp). Other metallic impurities, such as sodium and potassium, are determined by atomic absorption or emission spectrograph. For analysis, mbidium metal is converted to a compound such as mbidium chloride. 

Bromo-2-pyridyla2o)-5-diethylamiQophenol (5-Br-PADAP) is a very sensitive reagent for certain metals and methods for cobalt have been developed (23). Nitroso-naphthol is an effective precipitant for cobalt(III) and is used in its gravimetric determination (24,25). Atomic absorption spectroscopy (26,27), x-ray fluorescence, polarography, and atomic emission spectroscopy are specific and sensitive methods for trace level cobalt analysis (see... 

Pretreatment of the collected particulate matter may be required for chemical analysis. Pretreatment generally involves extraction of the particulate matter into a liquid. The solution may be further treated to transform the material into a form suitable for analysis. Trace metals may be determined by atomic absorption spectroscopy (AA), emission spectroscopy, polarogra-phy, and anodic stripping voltammetry. Analysis of anions is possible by colorimetric techniques and ion chromatography. Sulfate (S04 ), sulfite (SO-, ), nitrate (NO3 ), chloride Cl ), and fluoride (F ) may be determined by ion chromatography (15). 

There are now two main methods used for flame emission spectroscopy. The original method, known as flame photometry, is now used mainly for the analysis of alkali metals. 

The metal content analysis of the samples was effected by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES Varian Liberty II Instrument) after microwaves assisted mineralisation in hydrofluoric/hydrochloric acid mixture. Ultraviolet and visible diffuse reflectance spectroscopy (UV-Vis DRS) was carried out in the 200-900 nm range with a Lambda 40 Perkin Elmer spectrophotometer with a BaS04 reflection sphere. HF was used as a reference. Data processing was carried out with Microcal Origin 7.1 software. 

Also known as specific susceptibility. mas sa.sep-ta bil-ad-e mass-to-charge ratio analychem In analysis by mass spectroscopy, the measurement of the sample mass as a ratio to its ionic charge. mas to charj. ra sho ) matrix analy chem The analyte as considered in terms of its being an assemblage of constituents, each with its own properties. ma-triks matrix effects analy chem 1. The enhancement or suppression of minor element spectral lines from metallic oxides during emission spectroscopy by the matrix element (such as graphite) used to hold the sample. 2. The combined effect exerted by the various constituents of the matrix on the measurements of the analysis. ma triks i.feks )... 

Chapters 7 and 8 describe two major techniques for the monitoring of trace elements in environmental samples atomic absorption (AA) and inductively coupled plasma-atomic emission spectroscopy (ICP). AA is most ideally suited for analyses where a limited number of trace metal concentrations are needed with high accuracy and precision. ICP has the advantage of multielement analysis with high speed. 

Iron metal can be analyzed by x-ray spectroscopy, flame- and furnace atomic absorption, and ICP atomic emission spectroscopy at trace concentration levels. Other instrumental techniques include ICP-mass spectrometry for extreme low detection level and neutron activation analysis. 

Actinide metal samples are characterized by chemical and structure analysis. Multielement analysis by spark source mass spectrometry (SSMS) or inductively coupled argon plasma (ICAP) emission spectroscopy have lowered the detection limit for metallic impurities by 10 within the last two decades. The analysis of O, N, H by vacuum fusion requires large sample, but does not distinguish between bulk and surface of the material. Advanced techniques for surface analysis are being adapted for investigation of radioactive samples (Fig. 11) ... 

Atomic absorption and flame emission spectroscopy, also called flame photometry, are two methods of quantitative analysis that can be used to measure approximately 70 elements (metals and non-metals). Many models of these instruments allow measurements to be conducted by these two techniques, which rely on different principles. Their applications are numerous, as concentrations in the mg/l (ppm) region or lower can be accessed. 

The modern investigations of trace elements in coals were pioneered by Goldschmidt, who developed the technique of quantitative chemical analysis by optical emission spectroscopy and applied it to coal ash. In these earliest works, Goldschmidt (31) was concerned with the chemical combinations of the trace elements in coals. In addition to identifying trace elements in inorganic combinations with the minerals in coal, he postulated the presence of metal organic complexes and attributed the observed concentrations of vanadium, molybdenum, and nickel to the presence of such complexes in coal. 

Investigation of atomic spectra yields atomic energy levels. An important chemical application of atomic spectroscopy is in elemental analysis. Atomic absorption spectroscopy and emission spectroscopy are used for rapid, accurate quantitative analysis of most metals and some nonmetals, and have replaced the older, wet methods of analysis in many applications. One compares the intensity of a spectral line of the element being analyzed with a standard line of known intensity. In atomic absorption spectroscopy, a flame is used to vaporize the sample in emission spectroscopy, one passes a powerful electric discharge through the sample or uses a flame to produce the spectrum. Atomic spectroscopy is used clinically in the determination of Ca, Mg, K, Na, and Pb in blood samples. For details, see Robinson. 

Recently, a very important development has been made to enhance the ease of manipulation and the range of applicability of emission spectroscopy to trace metal analysis. This development is the plasma source which can be employed as an. accessory source in most direct reading emission spectrometers in place of the arc or spark or may be incorporated directly in the design of the spectrometer by the manufacturer. This development has been discussed in detail in the recent literature ( 9,53-58). 

Runge, E. F., and F. R. Bryan Micro-Analysis of Metals by Optical Emission Spectroscopy. Appl. Spectr. 13, 74 (1959). 

The chemical composition with respect to Si and metallic impurities (mainly Fe, Ca, Al) is generally determined by wet chemical methods in combination with standard spectroscopic techniques (AAS, AES, XRF) (Table 8) [224-226]. A precondition is the dissolution of the powder. Typical dissolving processes are fusion with sodium carbonate or mixtures of sodium carbonate and boric acid, with alkaline hydroxides [225, 226] and special acid treatments [225]. A more effective analysis based on optical emission spectroscopy allows the direct analysis of impurities in the solid state and requires no dissolution step [227]. 

Inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry have been applied to the determination of zinc, as discussed under Multi-Metal Analysis of Soils in Sects. 2.55 (inductively coupled plasma atomic emission spectrometry) and 2.55 (inductively coupled plasma mass spectrometry). Other techniques include atomic absorption spectrometry (Sect. 2.55), X-ray fluorescence spectroscopy (Sect. 2.55), electron probe microanalysis (Sect. 2.55), photon activation analysis (Sect. 2.55), emission spectrometry (Sect. 2.55), neutron activation analysis (Sect. 2.55), spectrophotometry (Sect. 2.55) and ion chromatography (Sect. 2.55). 

ANALYSIS OF METALS BY ATOMIC ABSORPTION AND EMISSION SPECTROSCOPY... 

Metals can be conveniently determined by emission spectroscopy using inductively coupled plasma (ICP). A great advantage of ICP emission spectroscopy as applied to environmental analysis is that several metals can be determined simultaneously by this method. Thus, multielement analysis of unknown samples can be performed rapidly by this technique. Another advantage is that, unlike atomic absorption spectroscopy, the chemical interference in this method is very low. Chemical interferences are generally attributed to the formation of molecular compounds (from the atoms) as well as to ionization and thermochemical effects. The principle of the ICP method is described below. 

Species distribution studies have shown that trace element (e.g. metals) concentrations in soils and sediments vary with physical location (e.g. depth below bed surface) and with particle size. In these speciation studies the total element content of each fraction was determined using a suitable trace element procedure, for example, solid sample analysis by X-ray emission spectroscopy or neutron activation analysis, or alternatively by dissolution of sample and analysis by ICPOES, AAS or ASV. The type of sample fraction analysed can vary, and a few... 

In 1952, Walsh in Australia realized the inherent advantages of atomic absorption spectroscopy over methods based on flame emission for quantitative analysis, and he has given a personal account of the development of the technique.197 Walsh s death in 1998 resulted in a memorial issue of the journal Spectrochimica Acta (B). As well as a brief biography of Walsh and a list of his publications, this contained 22 papers on all aspects of the history of atomic absorption spectroscopy. Together they constitute a valuable record of the birth of this important technique, the difficulties of bringing satisfactory instruments to market, and the history of the application of the method to quantify metals in a wide variety of materials and environments.198... 

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