Atomic absorption methods

Walsh, A. The Development of Atomic Absorption Methods of Elemental Analysis 1952-1962, Anal Chem. 1991, 63, 933A-941A. 

Chemical Analysis. Chemical analysis is deterrnined with conventional atomic absorption methods. Rehable wet techniques are sometimes employed (see Table 5). 

Chemical Analysis. Chemical impurities commonly analyzed include Na20, Fe202, and Si02. The hydroxide is first dissolved in boiling concentrated HQ. Atomic absorption methods have replaced older colorimetric procedures. 

On the basis of data obtained the possibility of substrates distribution and their D-values prediction using the regressions which consider the hydrophobicity and stmcture of amines was investigated. The hydrophobicity of amines was estimated by the distribution coefficient value in the water-octanole system (Ig P). The molecular structure of aromatic amines was characterized by the first-order molecular connectivity indexes ( x)- H was shown the independent and cooperative influence of the Ig P and parameters of amines on their distribution. Evidently, this fact demonstrates the host-guest phenomenon which is inherent to the organized media. The obtained in the research data were used for optimization of the conditions of micellar-extraction preconcentrating of metal ions with amines into the NS-rich phase with the following determination by atomic-absorption method. 

Ward, F.N. Nakagawa, H.M. Harms, T.F. Von Sickle, G.H. Atomic Absorption Methods of Analysis Useful in Geochemical Exploration, Geological Survey Bulletin 1289, Reston, VA, 1969 1-45. 

Reference methods are generally arrived at by consensus and fairly extensive testing by a number of laboratories. For example, the flame atomic absorption method for Ca in serum developed under the leadership of the agency fondly remembered as NBS, now NIST (Cali et al. 1972), was established after several inter-laboratory comparison exercises. The results were evaluated after each exercise and the procedure was changed as necessary. After five exercises, it was felt that the state-of-the-art had been reached, with the reference method being capable of measuring Ca in serum with an accuracy of 2% of the true value determined by IDMS (note that attainment of high accuracy and precision is not only a matter of the method, but is a function of both the method and analyst expertise). 

Ward FN, Nakagawa HM, Harms TF, VanSickle GH (t969) Atomic-absorption methods of analysis useful in geochemical exploration. U.S. Government Printing Office, Washington DC, 45 pp. 

Principles and Characteristics Flame emission instruments are similar to flame absorption instruments, except that the flame is the excitation source. Many modem instruments are adaptable for either emission or absorption measurements. Graphite furnaces are in use as excitation sources for AES, giving rise to a technique called electrothermal atomisation atomic emission spectrometry (ETA AES) or graphite furnace atomic emission spectrometry (GFAES). In flame emission spectrometry, the same kind of interferences are encountered as in atomic absorption methods. As flame emission spectra are simple, interferences between overlapping lines occur only occasionally. 

Mercury was determined after suitable digestion by the cold vapour atomic absorption method [40]. Lead was determined after digestion by a stable isotope dilution technique [41-43]. Copper, lead, cadmium, nickel, and cobalt were determined by differential pulse polarography following concentration by Chelex 100 ion-exchange resin [44,45], and also by the Freon TF extraction technique [46]. Manganese was determined by flameless atomic absorption spectrometry (FAA). 

Koide et al. [537] have described a graphite furnace atomic absorption method for the determination of rhenium at picomolar levels in seawater and parts-per-billion levels in marine sediments, based upon the isolation of heptavalent rhenium species upon anion exchange resins. All steps are followed with 186-rhenium as a yield tracer. A crucial part of the procedure is the separation of rhenium from molybdenum, which significantly interferes with the graphite furnace detection when the Mo Re ratio is 2 or greater. The separation is accomplished through an extraction of tetraphenylarsonium perrhenate into chloroform, in which the molybdenum remains in the aqueous phase. 

Negative interferences by transition metal cations such as nickel and copper and nitrite were observed. However, these interferences have also been reported for the hydride generation atomic absorption method, and are due to... 

A calibration exercise for an atomic absorption method to be used in the determination of a metal yielded the following results ... 

Flame emission spectrometry is used extensively for the determination of trace metals in solution and in particular the alkali and alkaline earth metals. The most notable applications are the determinations of Na, K, Ca and Mg in body fluids and other biological samples for clinical diagnosis. Simple filter instruments generally provide adequate resolution for this type of analysis. The same elements, together with B, Fe, Cu and Mn, are important constituents of soils and fertilizers and the technique is therefore also useful for the analysis of agricultural materials. Although many other trace metals can be determined in a variety of matrices, there has been a preference for the use of atomic absorption spectrometry because variations in flame temperature are much less critical and spectral interference is negligible. Detection limits for flame emission techniques are comparable to those for atomic absorption, i.e. from < 0.01 to 10 ppm (Table 8.6). Flame emission spectrometry complements atomic absorption spectrometry because it operates most effectively for elements which are easily ionized, whilst atomic absorption methods demand a minimum of ionization (Table 8.7). 

The analytical techniques used for additives analysis are reviewed below. They are mainly chromatographic but enzymatic, flow injection analysis, inductively coupled plasma-atomic emission spectrometry and atomic absorption methods are also used. 

An atomic absorption method was published by AOAC Int. (2000) for determination of the anti-foaming agent polydimethylsiloxane in pineapple juice, that is based on extraction with 4-methyl-2-pentanone and aspiration into a nitrous oxide/acetylene flame. A silicone lamp was used for detection. 

In general, atomic absorption methods are subject to three types of interferences, namely ... 

In short, liquid-liquid extraction has been employed predominantly and effectively not only for the pre-concentration and isolation of a single chemical entity just before its actual estimation, but also for the extraction of classes of organic compounds or groups of metals, just prior to their usual estimation either by chromatographic techniques or by atomic-absorption methods. 

Analytical Techniques Atomic absorption spectrometry, 158, 117 multielement atomic absorption methods of analysis, 158, 145 ion microscopy in biology and medicine, 158, 157 flame atomic emission spectrometry, 158, 180 inductively coupled plasma-emission spectrometry, 158, 190 inductively coupled plasma-mass spectrometry, 158, 205 atomic fluorescence spectrometry, 158, 222 electrochemical methods of analysis, 158, 243 neutron activation analysis, 158, 267. 

Colovos, G. Eaton, W.S. Ricci, G.R. Shepard, L.S., Wang, H. Collaborative Testing of NIOSH Atomic Absorption Method , DHEW (NIOSH) Publication No. 79-1 Wt, 1978. 

C. D. Stalikas, G. A. Pilidis and M. I. Karayannis, Determination of lead and cadmium in environmental samples by simplex optimised atomic absorption methods, J. Anal. At. Spectrom., 11(8), 1996, 595-599. 

Contrary to potentiometric methods that operate under null current conditions, other electrochemical methods impose an external energy source on the sample to induce chemical reactions that would not otherwise spontaneously occur. It is thus possible to measure all sorts of ions and organic compounds that can either be reduced or oxidised electrochemically. Polarography, the best known of voltammetric methods, is still a competitive technique for certain determinations, even though it is outclassed in its present form. It is sometimes an alternative to atomic absorption methods. A second group of methods, such as coulometry, is based on constant current. Electrochemical sensors and their use as chromatographic detectors open new areas of application for this arsenal of techniques. 

Only one NAA determination was made on each of the 10 coals studied by O Gorman et al. No estimate of the method s precision or sensitivity is given. Combustion-double gold amalgamation-atomic absorption results agreed well with the neutron activation results, and the former method was therefore considered to be more reliable than a combustion-solution-atomic absorption method that gave lower results. 

The flameless atomic absorption method has a reproducibility of about 2% or better for homogeneous specimens. Checks (3) between AA and NAA (with radiochemical separation after irradiation) and isotope dilution spark source mass spectroscopy on thoroughly homogenized tuna fish and Bureau of Mines round-robin coal specimens indicate good agreement between the methods. (0.425 0.9%, 0.45 3.5%, and 0.45 4.4% for tuna by AA, NAA, and SSMS, respectively, and 1.004 is the average ratio of NAA to AA results for five coal samples.) The similar results indicate that the technique used in sample preparation... 

Soldatenkova NA, Smirnov VG. 1983. [Atomic absorption method of determining silver in the air]. Gig Tr Prof Zabol, Issue 6, 53-54. (Russian). 

It is, of course, possible to determine the amount of silicon present in a sample by pyrolysis to silica, followed by atomic absorption methods. 

ASTM D-4606. Standard Test Method for Determination of Arsenic and Selenium in Coal by the Hydride Generation/Atomic Absorption Method. 

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