Atomic absorption spectrometry furnace

Atomic absorption spectrometry furnace tubes are supplied with a hard pyrolytic graphite surface. This helps to reduce the porosity of the tube, which minimizes adsorption of hot metal vapors and slows down the rate of oxidation of the graphite and the accompanying mechanical degradation of the furnace tube. 

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. 

L Vov, B. V. Graphite Furnace Atomic Absorption Spectrometry, AuflZ. Chem. 1991, 63, 924A-931A. 

Highly sensitive iastmmental techniques, such as x-ray fluorescence, atomic absorption spectrometry, and iaductively coupled plasma optical emission spectrometry, have wide appHcation for the analysis of silver ia a multitude of materials. In order to minimize the effects of various matrices ia which silver may exist, samples are treated with perchloric or nitric acid. Direct-aspiration atomic absorption (25) and iaductively coupled plasma (26) have silver detection limits of 10 and 7 l-lg/L, respectively. The use of a graphic furnace ia an atomic absorption spectrograph lowers the silver detection limit to 0.2 l-ig/L. 

Numerous methods have been pubUshed for the determination of trace amounts of tellurium (33—42). Instmmental analytical methods (qv) used to determine trace amounts of tellurium include atomic absorption spectrometry, flame, graphite furnace, and hydride generation inductively coupled argon plasma optical emission spectrometry inductively coupled plasma mass spectrometry neutron activation analysis and spectrophotometry (see Mass spectrometry Spectroscopy, optical). Other instmmental methods include polarography, potentiometry, emission spectroscopy, x-ray diffraction, and x-ray fluorescence. 

Electrothermal vaporization can be used for 5-100 )iL sample solution volumes or for small amounts of some solids. A graphite furnace similar to those used for graphite-furnace atomic absorption spectrometry can be used to vaporize the sample. Other devices including boats, ribbons, rods, and filaments, also can be used. The chosen device is heated in a series of steps to temperatures as high as 3000 K to produce a dry vapor and an aerosol, which are transported into the center of the plasma. A transient signal is produced due to matrix and element-dependent volatilization, so the detection system must be capable of time resolution better than 0.25 s. Concentration detection limits are typically 1-2 orders of magnitude better than those obtained via nebulization. Mass detection limits are typically in the range of tens of pg to ng, with a precision of 10% to 15%. 

Figure 15-12 is a schematic illustration of a technique known as acid volatile sulfides/ simultaneously extracted metals analysis (AVS/SEM). Briefly, a strong acid is added to a sediment sample to release the sediment-associated sulfides, acid volatile sulfides, which are analyzed by a cold-acid purge-and-trap technique (e.g., Allen et ai, 1993). The assumption shown in Fig. 15-12 is that the sulfides are present in the sediments in the form of either FeS or MeS (a metal sulfide). In a parallel analysis, metals simultaneously released with the sulfides (the simultaneously extracted metals) are also quantified, for example, by graphite furnace atomic absorption spectrometry. Metals released during the acid attack are considered to be associated with the phases operationally defined as "exchangeable," "carbonate," "Fe and Mn oxides," "FeS," and "MeS."... 

Vol. 149. A Practical Guide to Graphite Furnace Atomic Absorption Spectrometry. By David J. Butcher and Joseph Sneddon... 

Asplla, K. I., Chakrabartl, C. L., and Bratzel, M. P., Jr. "Pyrolytic Graphite-Tube Micro-Furnace for Trace Analysis by Atomic Absorption Spectrometry". Anal. Chem. (1972),... 

Cruz, R. B. and Loon, J. C. van "A Critical Study of the Application of Graphite-Furnace Non-Flame Atomic Absorption Spectrometry to the Determination of Trace Base Metals In Complex Heavy-Matrix Sample Solutions". Anal. Chlm. Acta (1974), 72, 231-243. 

Davidson, I. W. F. and Secrest, W. L. "Determination of Chromium In Biological Materials by Atomic Absorption Spectrometry Using a Graphite Furnace Atomizer". Anal. 

Kamel, H., Brown, D.H., Ottaway, J.M. and Smith, W.E. (1977) Determination of gold in separate protein fractions of blood serum by carbon furnace atomic-absorption spectrometry. Analyst, 102, 645-663. 

Nowka R, Muller H (1997) Direct analysis of solid samples by graphite furnace atomic absorption spectrometry with a transversely heated graphite atomizer and D2-background correction system (SS GF-AAS). Fresenius J Anal Chem 359 132-137. 

Backmank S, Karlsson RW (1979) Determination of lead, bismuth, zinc, silver and antimony in steel and nickel-base alloys by atomic-absorption spectrometry using direct atomization of solid samples in a graphite furnace. Analyst 104 1017-1029. 

Hinds MW (1993) Determination of gold, palladium and platinum in high purity silver by different solid sampling graphite furnace atomic absorption spectrometry methods, Spectrochim Acta 48B 435-445. 

Klemm W, Baumeach G (1995) Trace element determination in contaminated sediments and soils by ultrasonic slurry sampling and Zeeman graphite furnace atomic absorption spectrometry. Fresenius J Anal Chem 353 12-15. 

LtiCKER E, Konig H, Gabriel G, Rosopulo A (1992) Analytical quality control by solid sampling graphite furnace atomic absorption spectrometry in the production of animal tissue reference materials. Fresenius J Anal Chem 342 941-949. 

Kelko-Levai, A., Varga, I., Zih-Perenyi, K., and Lasztity, A., Determination of trace elements in pharmaceutical substances by graphite furnace atomic absorption spectrometry and total reflection X-ray fluorescence after flow injection ion-exchange preconcentration, Spectrochim. Acta Pt. B, 54, 827, 1999. 

ZGFAAS Zeeman graphite furnace atomic absorption spectrometry... 

Aroza I, Bonilla M, Madrid Y, et al. 1989. Combination of hydride generation and graphite furnace atomic absorption spectrometry for the determination of lead in biological samples. J Anal Atmos Spectra 4 163-166. 

Ellen G, Van Loon JW. 1990. Determination of cadmium and lead in foods by graphite furnace atomic absorption spectrometry with Zeeman background correction Test with certified reference materials. Food Addit Contam 7 265-273. 

Zhang Z-W, Shimbo S, Ochi N, et al. 1997. Determination of lead and cadmium in food and blood by inductively coupled plasma mass spectrometry a comparison with graphite furnace atomic absorption spectrometry. Science of the Total Environment 205(2-3) 179-187. 

Chapters 5 and 6 discuss the application of new techniques such as atomic absorption spectrometry with and without graphite furnace and Zeeman background correction, inductively coupled plasma mass spectrometry, X-ray fluo-... 

Zeeman Graphite Furnace Atomic Absorption Spectrometry... 

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. 

Many of the published methods for the determination of metals in seawater are concerned with the determination of a single element. Single-element methods are discussed firstly in Sects. 5.2-5.73. However, much of the published work is concerned not only with the determination of a single element but with the determination of groups of elements (Sect. 5.74). This is particularly so in the case of techniques such as graphite furnace atomic absorption spectrometry, Zeeman background-corrected atomic absorption spectrometry, and inductively coupled plasma spectrometry. This also applies to other techniques, such as voltammetry, polarography, neutron activation analysis, X-ray fluroescence spectroscopy, and isotope dilution techniques. 

Bishop [75] determined barium in seawater by direct injection Zeeman-modulated graphite furnace atomic absorption spectrometry. The V203/Si modifier added to undiluted seawater samples promotes injection, sample drying, graphite tube life, and the elimination of most seawater components in a slow char at 1150-1200 °C. Atomisation is at 2600 °C. Detection is at 553.6 nm and calibration is by peak area. Sensitivity is 0.8 absorbance s/ng (Mo = 5.6 pg 0.0044 absorbance s) at an internal argon flow of 60 ml/min. The detection limit is 2.5 pg barium in a 25 ml sample or 0.5 pg using a 135 ml sample. Precision is 1.2% and accuracy is 23% for natural seawater (5.6-28 xg/l). The method works well in organic-rich seawater matrices and sediment porewaters. 

Epstein and Zander [76] used graphite furnace atomic absorption spectrometry for the direct determination of barium in seawater and estuarine... 

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