Atomic absorption spectrophotometry element analysis

BeryUium aUoys ate usuaUy analyzed by optical emission or atomic absorption spectrophotometry. Low voltage spark emission spectrometry is used for the analysis of most copper-beryUium aUoys. Spectral interferences, other inter-element effects, metaUurgical effects, and sample inhomogeneity can degrade accuracy and precision and must be considered when constmcting a method (17). 

Cabezon et al. [662] simultaneously separated copper, cadmium, and cobalt from seawater by coflotation with octadecylamine and ferric hydroxide as collectors prior to analysis of these elements by flame atomic absorption spectrometry. The substrates were dissolved in an acidified mixture of ethanol, water, and methyl isobutyl ketone to increase the sensitivity of the determination of these elements by flame atomic absorption spectrophotometry. The results were compared with those of the usual ammonium pyrrolidine dithiocarbamate/methyl isobutyl ketone extraction method. While the mean recoveries were lower, they were nevertheless considered satisfactory. 

Gold may be identified by its physical properties. Trace quantities of gold may be analyzed by flame atomic absorption spectrophotometry (to 1 ppm) or by neutron activation analysis (to 1 ppb). The metal may be dissolved in aqua regia and the solution diluted appropriately prior to analysis. The most sensitive wavelength for this element is 242.8nm. 

In a search for sources of alkaline materials in rural air and rain, we have sampled and performed multi-element analyses on ambient particulate matter and potential source materials. Ambient aerosols were sampled daily using single Nuclepore filters or Florida State University "streakers." Samples of soil and unpaved road materials were also collected and analyzed. The samples were analyzed by various multi-element methods, including ion-and proton-induced X-ray emission and X-ray fluorescence, as well as by atomic absorption spectrophotometry. Visual observations, as well as airborne elemental concentration distributions with wind direction and elemental abundances in aerosols and source materials, suggested that soil and road dust both contribute to airborne Ca. Factor analysis was able to identify only a "crustal" source, but a simple mass balance suggested that roads are the major source of Ca in rural central Illinois in summer. 

Sample analyses were carried out by a number of laboratories. We are grateful to Mr. Mark E. Peden and Ms. Loretta M. Skowron of the Water Survey s Analytical Chemistry Laboratory Unit for atomic absorption spectrophotometry, Mr. L. R. Henderson of the Illinois State Geological Survey for X-ray Fluorescence specto-scopy, and Dr. T. A. Cahill of the University of Califomia-Davis for elemental analysis. Mr. R. G. Semonin reviewed the manuscript. This material is based upon work supported by the National Science Foundation under Grant No. ATM-7724294, and by the Department of Energy, Division of Biomedical and Environmental Research, under Contract No. EY-76-S-02-1199. 

Atomic absorption spectrophotometry is another technique for trace element determinations used in environmental analysis by EPA 7000 and 200 analytical method series. In contrast to ICP-AES, which is based on the detection of ionized species emission spectra, in AA methods the elements are detected by the quantity of the radiation they absorb in the unexcited, free atom state. 

One of the most challenging aspects of atomic spectrometry is the incredibly wide variety of sample types that require elemental analysis. Samples cover the gamut of solids, liquids, and gases. By the nature of most modem spectrochemical methods, the latter two states are much more readily presented to sources that operate at atmospheric pressure. The most widely used of these techniques are flame and graphite furnace atomic absorption spectrophotometry (FAAS and GF-AAS) [1,2] and inductively coupled plasma atomic emission and mass spectrometries (ICP-AES and MS) [3-5]. As described in other chapters of this volume, ICP-MS is the workhorse technique for the trace element analysis of samples in the solution phase—either those that are native liquids or solids that are subjected to some sort of dissolution procedure. 

Trace element analysis of foods can be carried out to check for contamination by toxic elements, such as lead and cadmium, or to determine beneficial micronutrients, or as an aid to distinguishing geographical origin. In fats, small numbers of trace elements are measured after digestion of the sample in acid followed atomic absorption spectrophotometry (AAS) or by direct graphite furnace vaporization. An AAS procedure for measuring lead in edible oils and fats has been collaboratively trialed with cocoa butter as a test material (Firestone, 1994). 

The selection of the method of analysis is a vital step in the solution of an analytical problem. A choice cannot be made until the overall problem is defined, and where possible a decision should be taken by the client and the analyst in consultation. Inevitably, in the method selected, a compromise has to be reached between the sensitivity, precision and accuracy desired of the results and the costs involved. For example. X-ray fluorescence spectrometry may provide rapid but rather imprecise quantitative results in a trace element problem. Atomic absorption spectrophotometry, on the other hand, will supply more precise data, but at the expense of more time consuming chemical manipulations. 

Because each element absorbs at very discrete wavelengths, the lamp used for analysis of a particular metal emits light only at the desired wavelengths and is specific for that element. The two kinds of lamps used in atomic absorption spectrophotometry are the hollow cathode lamp (HCL) and the electrodeless discharge... 

Table 1 shows the detection limits of atomic absorption spectrophotometry for various metals. In general, flame atomic absorption spectrophotometry is quantitative in the lower parts-per-million levels and is readily automated for routine, high-volume samples. The other three techniques are used primarily for trace analysis and are quantitative to the lower parts-per-million levels for many elements. 

Atomic absorption spectrophotometry already then in its second edition. Price (1974) (Analytical Atomic Absorption Spectrometry) published about thelOth book on AAS since inception of the technique with the aim of being a textbook on practical AAS (FAAS). It contains the usual introduction to principles, instrumenttation and analytical techniques, with a large detailed chapter of applications to different materials followed by details for individual elements. A nice expanded version of the author s first book (Price 1979) on Spectrochemical Analysis by Atomic Absorption, includes newer developments such as EAAS. Kirkbright and Sargent (1974) (Atomic Absorption and Fluorescence Spectrometry) produced a massive, excellent, comprehensive treatise on the techniques of atomic absorption and fluorescence spectrometries, with details on... 

Hunt, B.J. (1969). The estimation of magnesium in plasma, muscle and bone, by atomic absorption spectrophotometry, Clin. Chem. 15, 979-996 lida, C., Uchida, T. and Kojima, I. (1980). Decomposition of bovine liver in a sealed teflon vessel for determination of metals by AAS, Anal. Chim. Acta, 113, 365 International Atomic Energy Agency (1978). Activation analysis of hair as an indicator of contamination of man by environmental trace element pollutants. A report of the co-ordinated research programme on nuclear based methods for analysis of pollutants in human hair. IAEA/RU/50... 

Analytical. Chitln and chitosan samples, diets, fecal samples and animal carcasses were wet digested In HNO -HCIO prior to element analysis. Determination of Ca, Mg, Fe, Zn and Cu were by atomic absorption spectrophotometry (23) Phosphorus was measured by the method of Fiske-Subbarow (24). 

Determination of the rare-element content in rock samples is a more difficult analytical problem than determination of the main components. The development of optical spectroscopy, X-ray fluorescence analysis, atomic absorption spectrophotometry (AAS), mass spectrometry and other analytical methods from the middle of the 20 century made careful mapping of the composition of the crust possible, even for the rarer elements. The content of each element is given in the corresponding element chapter. 

IR is an absorption method. Analysis utilizing absorption measurements can also be done with spectrophotometry and atomic absorption spectrophotometry (AAS). In the former method a monochromatic light (visible or ultraviolet) is passed through a solution containing a compound of an element with unknown concentration. The light absorption is measured and converted to concentration. 

The instrument is usually calibrated by measuring the absorbance produced by a range of standard solutions and then plotting an empirical working curve. In this way atomic absorption spectrophotometry may be used for the analysis of some 68 elements and in many cases the limit of sensitivity is as low as 0 1 parts per million. Unfortunately the assumption that the linewidth of the source... 

Elemental composition A1 52.91%, 0 47.08%. A1 may be anlayzed by atomic absorption or emission spectrophotometry or by colorimetric methods after acid digestion. Different forms of alumina may be identified by x-ray diffraction analysis. The X-ray crystallogaphic data for the mineral corundum are as follows ... 

Elemental analysis A1 15.77% O 56.12% S 28.11%. A1 may he determined hy colorimetric method or hy atomic absorption or emission spectrophotometry sulfate may he determined by BaCb precipitation method in the aqueous solution of the salt. 

The element may be analyzed by several instrumental techniques including atomic absorption and emission spectrophotometry, ICP-MS, x-ray fluorescence, and neutron activation analysis. 

All metals at trace concentration, or in trace quantities, can be analyzed by atomic absorption (AA) spectrophotometry in flame or graphite furnace (electrothermal reduction) mode. A rapid, multi-element analysis may use... 

Various spectroscopic techniques such as flame photometry, emission spectroscopy, atomic absorption spectrometry, spectrophotometry, flu-orimetry, X-ray fluorescence spectrometry, neutron activation analysis and isotope dilution mass spectrometry have been used for marine analysis of elemental and inorganic components [2]. Polarography, anodic stripping voltammetry and other electrochemical techniques are also useful for the determination of Cd, Cu, Mn, Pb, Zn, etc. in seawater. Electrochemical techniques sometimes provide information on the chemical species in solution. 

Many researchers have attempted to determine mercury levels in the blood, urine, tissues, and hair of humans and animals. Most methods have used atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), or neutron activation analysis (NAA). In addition, methods based on mass spectrometry (MS), spectrophotometry, and anodic stripping voltametry (ASV) have also been tested. Of the available methods, cold vapor (CV) AAS is the most widely used. In most methods, mercury in the sample is reduced to the elemental state. Some methods require predigestion of the sample prior to reduction. At all phases of sample preparation and analysis, the possibility of contamination from mercury found naturally in the environment must be considered. Rigorous standards to prevent mercury contamination must be followed. Table 6-1 presents details of selected methods used to determine mercury in biological samples. Methods have been developed for the analysis of mercury in breath samples. These are based on AAS with either flameless (NIOSH 1994) or cold vapor release of the sample to the detection chamber (Rathje et al. 1974). Flameless AAS is the NIOSH-recommended method of determining levels of mercury in expired air (NIOSH 1994). No other current methods for analyzing breath were located. 

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