Standards atomic absorption spectrometry

Atsuya I, Itoh K, Ariu K. 1991. Preconcentration by coprecipitation of lead and selenium with nickel-pyrrolidine dithiocarbamate complex and their simultaneous determination by internal standard atomic absorption spectrometry with the solid sampling technique. Pure Appl Chem 63(9) 1221-1226. 

The AOAC and Codex recommended methods for determination of potassium and sodium are by flame atomic emission spectrometry. These methods have the advantage of quick and simple sample preparation, aqueous dilution of sample and filtration, with rapid, reasonably accurate detection. The samples can be aspirated directly into the flame and the readings quantified by comparison with a range of known standards. Atomic absorption spectrometry can also be used, giving increased accuracy and low-level sensitivity and a far wider range of detectable... 

From J. A. Dean and T. C. Rains, Standard Solutions for Flame Spectrometry, in Flame Emission and Atomic Absorption Spectrometry, J. A. Dean and T. C. Rains (Eds.), Vol. 2, Chap. 13, Marcel Dekker, New York, 1971. 

Trace metals in sea water are preconcentrated either by coprecipitating with Ee(OH)3 and recovering by dissolving the precipitate or by ion exchange. The concentrations of several trace metals are determined by standard additions using graphite furnace atomic absorption spectrometry. 

The complex of the following destmctive and nondestmctive analytical methods was used for studying the composition of sponges inductively coupled plasma mass-spectrometry (ICP-MS), X-ray fluorescence (XRF), electron probe microanalysis (EPMA), and atomic absorption spectrometry (AAS). Techniques of sample preparation were developed for each method and their metrological characteristics were defined. Relative standard deviations for all the elements did not exceed 0.25 within detection limit. The accuracy of techniques elaborated was checked with the method of additions and control methods of analysis. 

Methods. As discussed in the previous chapter, a number of approaches have been used to assess the presence of potentially toxic trace elements in water. The approaches used in this assessment include comparative media evaluation, a human health and aquatic life guidelines assessment, a mass balance evaluation, probability plots, and toxicity bioassays. Concentrations of trace elements were determined by atomic absorption spectrometry according to standard methods (21,22) by the Oregon State Department of Environmental Quality and the U.S. Geological Survey. 

Haghighi, B., Maleki, N., and Safavi, A., Standard Additions in Flow-Injection Analysis with Atomic Absorption Spectrometry, Analytica Chimica Acta 357, 1997, 151-156. 

Aqueous standard solutions are a source of certain difficulties In electrothermal atomic absorption spectrometry of trace metals In biological fluids The viscosities and surface tensions of aqueous standard solutions are substantially less than the viscosities and surface tensions of serum, blood and other proteln-contalnlng fluids These factors Introduce volumetric disparities In pipetting of standard solutions and body fluids, and also cause differences In penetration of these liquids Into porous graphite tubes or rods Preliminary treatment of porous graphite with xylene may help to minimize the differences of liquid penetration (53,67) A more satisfactory solution of this problem Is preparation of standards In aqueous solutions of metal-free dextran (50-60 g/llter), as first proposed by Pekarek et al ( ) for the standardization of serum chromium analyses This practice has been used successfully by the present author for standardization of analyses of serum nickel The standard solutions which are prepared In aqueous dextran resemble serum In regard to viscosity and surface tension Introduction of dextran-contalnlng standard solutions Is an Important contribution to electrothermal atomic absorption analysis of trace metals In body fluids. 

Schramel, P. "Determination of Eight Metals In the International Biological Standard by Flameless Atomic Absorption Spectrometry". Anal. Chlm. Acta (1973), 67 69-77. 

Test Methods for Lead in Gasoline Method 1-Standard method test for lead in gasoline by atomic absorption spectrometry Yes 40 CFR 80, App. B EPA 1974... 

Eaton AD, Clesceri LS, Greenberg AE. 1995b. Method 3111, Metals by Flame Atomic Absorption Spectrometry, Standard Methods for the Examination of Water and Wastewater, American Public Health Association, Washington, DC. 

Ho M.D., Evans G.J. Operational speciation of cadmium, copper, lead and zinc in the NIST standard reference materials 2710 and 2711 (Montana soil) by the BCR sequential extraction procedure and flame atomic absorption spectrometry. Anal Commun 1997 34 353-364. 

A limited amount of work has been carried out on the determination of molybdenum in seawater by AAS [107-109] and graphite furnace atomic absorption spectrometry [110]. In a recommended procedure a 50 ml sample at pH 2.5 is preconcentrated on a column of 0.5 gp-aminobenzylcellulose, then the column is left in contact with 1 mol/1 ammonium carbonate for 3 h, after which three 5 ml fractions are collected. Finally, molybdenum is determined by AAS at 312.2 nm with use of the hot-graphite-rod technique. At the 10 mg/1 level the standard deviation was 0.13 xg. 

Benzwi [409] determined lithium in Dead Sea water using atomic absorption spectrometry. The sample was passed through a 0.45 pm filter and lithium was then determined by the method of standard additions. Solutions of lithium in hexanol and 2-ethylhexanol gave greatly enhanced sensitivity. 

Trace amounts of molybdenum were concentrated from acidified seawater on a strongly basic anion exchange resin (Bio-Rad AG1 X-8 in the chloride form) by treating the water with sodium azide. Molybdenum (VI) complexes with azide were stripped from the resin by elution with ammonium chlo-ride/ammonium hydroxide solution (2 M/2 M). Relative standard deviations of better than 8% at levels of 10 xg per litre were attained for seawater using graphite furnace atomic absorption spectrometry. 

Carr [562] has studied the effects of salinity on the determination of strontium in seawater by atomic absorption spectrometry using an air-acetylene flame. Using solutions containing 7.5 mg/1 strontium and between 5 and 14% sodium chloride, he demonstrated a decrease in absorption with increasing sodium chloride concentration. To overcome this effect a standard additions procedure is recommended. 

The average concentration and standard deviation of the Pacific Ocean waters ( xg/l) were 2.00 0.09 by neutron activation analysis, and 1.86 0.12 by atomic absorption spectrometry. For the Adriatic water the corresponding values were about 1.7 xg/l. The difference between the values for the same seawater is within the range to be expected from the standard deviations observed. 

A method described by Hirata and Honda [618] uses a flow injection analysis manifold for pH adjustment of a seawater sample, followed by concentration of zinc on a column packed with Chelex 100 resin. The zinc was eluted with nitric acid and determined by atomic absorption spectrometry. The detection limit is 0.5 p,g/l and the relative standard deviation is 2.7% at the 10 ig/l level. 

Fang et al. [661] have described a flow injection system with online ion exchange preconcentration on dual columns for the determination of trace amounts of heavy metal at pg/1 and sub-pg/1 levels by flame atomic absorption spectrometry (Fig. 5.17). The degree of preconcentration ranges from a factor of 50 to 105 for different elements, at a sampling frequency of 60 samples per hour. The detection limits for copper, zinc, lead, and cadmium are 0.07, 0.03, 0.5, and 0.05 pg/1, respectively. Relative standard deviations are 1.2-3.2% at pg/1 levels. The behaviour of the various chelating exchangers used was studied with respect to their preconcentration characteristics, with special emphasis on interferences encountered in the analysis of seawater. 

Orren [663] used atomic absorption spectrometry to determine these elements in seawater in both their soluble and insoluble forms. The alkali metals are determined directly, but the other elements are first concentrated by solvent extraction. The particulate matter content is derived by dissolving the membranes used to filter the sample and determine the metals in the resulting solution. For organic standards of known metal content, the efficiency of the technique was almost 100%. 

Hatcher, H., Tite, M.S. and Walsh, J.N. (1995). A comparison of inductively-coupled plasma emission spectrometry and atomic absorption spectrometry analysis on standard reference silicate materials and ceramics. Archaeometry 37 83-94. 

Table 12.13 compares results obtained by this method with those obtained by a molybdenum blue method of spectrophotometry [115, 116]. Values obtained by atomic absorption spectrometry are higher than those obtained by the molybdenum blue method and this is believed to reflect the greater inherent accuracy of the former method. A UK standard method also... 

Once the sample is in solution in the acid and the digest made up to a standard volume the determination of metals is completed by standard procedures such as atomic absorption spectrometry or inductively coupled plasma optical emission spectrometry. 

A convenient method is the spectrometric determination of Li in aqueous solution by atomic absorption spectrometry (AAS), using an acetylene flame—the most common technique for this analyte. The instrument has an emission lamp containing Li, and one of the spectral lines of the emission spectrum is chosen, according to the concentration of the sample, as shown in Table 2. The solution is fed by a nebuhzer into the flame and the absorption caused by the Li atoms in the sample is recorded and converted to a concentration aided by a calibration standard. Possible interference can be expected from alkali metal atoms, for example, airborne trace impurities, that ionize in the flame. These effects are canceled by adding 2000 mg of K per hter of sample matrix. The method covers a wide range of concentrations, from trace analysis at about 20 xg L to brines at about 32 g L as summarized in Table 2. Organic samples have to be mineralized and the inorganic residue dissolved in water. The AAS method for determination of Li in biomedical applications has been reviewed . 

Nickel is normally present at very low levels in biological samples. To determine trace nickel levels in these samples accurately, sensitive and selective methods are required. Atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES), with or without preconcentration or separation steps, are the most common methods. These methods have been adopted in standard procedures by EPA, NIOSH, lARC, and the International Union of Pure and Applied... 

Atomic absorption spectrometry (AA). This is a standard laboratory analytical tool for metals. The metal is extracted into a solution and then vaporized in a flame. A light beam with a wavelength absorbed by the metal of interest passes through the vaporized sample for example, to measure zinc, a zinc resonance lamp can be used so that the emission and absorbing wavelengths are perfectly matched. The absorption of the light by the sample is measured and Beer s law is applied to quantify the amount present. 

The following blank-corrected readings were obtained for the determination of nickel in steel, using nickel standards dissolved in iron solution (10 g k ). The determination was performed by atomic absorption spectrometry using an air-acetylene flame and the 232 nm nickel line. 

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