Electrothermal atomization chromium

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. 

The collection behaviour of chromium species was examined as follows. Seawater (400 ml) spiked with 10-8 M Crm, CrVI, and Crm organic complexes labelled with 51Cr was adjusted to the desired pH by hydrochloric acid or sodium hydroxide. An appropriate amount of hydrated iron (III) or bismuth oxide was added the oxide precipitates were prepared separately and washed thoroughly with distilled water before use [200]. After about 24 h, the samples were filtered on 0.4 pm nucleopore filters. The separated precipitates were dissolved with hydrochloric acid, and the solutions thus obtained were used for /-activity measurements. In the examination of solvent extraction, chromium was measured by using 51Cr, while iron and bismuth were measured by electrothermal atomic absorption spectrometry. The decomposition of organic complexes and other procedures were also examined by electrothermal atomic absorption spectrometry. 

The elements covered are aluminium, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel, vanadium, and zinc. Electrothermal atomic absorption and anodic and cathodic scanning voltammetric methods are discussed. 

Figure 2.37 Analysis of chromium by atomic absorption spectrophotometry using electrothermal atomization.

J. C. Rodriguez-Garcia, J. Barciela-Garcia, C. Herrero-Latorre, S. Garcia-Martin and R. M. Pena-Crecente, Direct and combined methods for the determination of chromium, copper and nickel in honey by electrothermal atomic absorption spectroscopy, J. Agric. Food Chem., 53(17), 2005, 6616-6623. 

The sequential extraction of chromium from soils has been studied [89]. A three-step sequential extraction scheme has been proposed using acetic acid, hydroxylamine hydrochloride and ammonium acetate as extracting agents. Steps 1 and 2 were measured by electrothermal atomic absorption spectrometry (ETAAS). Step 3 was measured by flame atomic absorption spectrometry. Interfering effects when measuring chromium in soils were circumvented through the use of a 1% 5-hydroxyquinoline suppressor agent. 

One example may illustrate the algorithm used for error resolution (for mathematical details see also [DOERFFEL, 1990]) Four samples were taken simultaneously from the same location in a river. These samples were divided into four subsamples and centrifuged in order to separate the suspended material. The subsamples were then analyzed four times and the chromium concentration was determined by means of AAS with electrothermal atomization. By following this procedure, error resolution for these origins of variance is possible ... 

Tab. 4-2. Contributions to variance in the analysis of chromium in river water samples using AAS with electrothermal atomization...

In 140 water samples from the river Saale, sampled from 1986 to 1988 according to the technique described in Section 8.1.1.1, the heavy metals iron and zinc were determined using flame AAS and lead, cadmium, chromium, cobalt, copper, and nickel by AAS with electrothermal atomization in the soluble fraction (particle diameter <0.45 pm). The sampling points, located in Thuringia (Germany), are illustrated in Fig. 8-7. The method of standard addition, with three additions, was used to minimize matrix effects. The components ammonium, chloride, magnesium, nitrate, nitrite, phosphate, oxygen,... 

In analytical spectrometry there are many types of calibration curves which are set up by measuring spectrometric reference solutions. The measurements yield a curve of absorbance versus concentration, and the points between the data of the reference solutions are interpolated by fitting a suitable curve, which normally follows the Beer-Lambert law and which gives rise to a straight line through the origin of the coordinate system. The measurement conditions and the results of the calibration curve evaluations in the case of chromium and lead measurements by electrothermal atomic absorption spectrometry are presented in Table 1. 

Batley, G.E. and J.P Matousek. 1980. Determination of chromium speciation in natural waters by electrodeposition on graphite tubes for electrothermal atomization. Anal. Chem. 52 1570-1574. 

The determination of chromium in most biological samples is difficult because of the matrix interference and the very low concentrations present in these samples. Prior to 1978, numerous erroneous results were reported for the chromium level in urine using electrothermal atomic absorption spectrometry (EAAS) because of the inability of conventional atomic absorption spectrometry systems to correct for... 

Harnley JM, Patterson KY, Veillon C, et al. 1983. Comparison of electrothermal atomic absorption spectrometry and atomic emission spectrometry for determination of chromium in urine. Anal Chem 55 1417-1419. 

Lendinez E, Lopez MC, Cabrera C, et al. 1998. Determination of chromium in wine and other alcoholic beverages consumed in Spain by electrothermal atomic absorption spectometry. J Aoac Int 8(5) 1043-1047. 

Stupar J, Dolinsek F. 1996. Determination of chromium, manganese, lead and cadmium in biological samples including hair using direct electrothermal atomic absorption spectrometry. Spectrochim Acta Part B 51 665-683. 

Veillon C, Patterson KY, Bryden NA. 1982. Determination of chromium in human urine by electrothermal atom absorption spectrometry. Anal Chim Acta 136 344. 

P. Vinas, N. Campillo, I. Lopez-Garcia, M. Hemandez-Cordoba, Electrothermal atomic absorption spectrometric determination of molybdenum, aluminium, chromium and manganese in milk, Anal. Chim. Acta, 356 (1997), 267-276. 

Y. He, M. L. Cervera, A. Pastor, M. de la Guardia, Determination of chromium (III) and chromium (VI) in mineral water by bidirectional electrostacking and electrothermal atomic absorption spectrometry, Anal. Chim. Acta., 447 (2001), 135-142. 

M. H. Canuto, H. G. Luna Siebald, G. Magela de Lima, J. B. Borda Silva, Antimony and chromium determination in Brazilian sugar cane spirit, cachaca, by electrothermal atomic absorption spectrometry using matrix matching calibration and ruthenium as permanent modifier, J. Anal. Atom Spectrom., 18 (2003), 1404-1406. 

Schermeier AJ, O Coimor LH, Pearson KH. Semi-automated determination of chromium in whole blood and serum by Zeeman electrothermal atomic absorption spectrophotometry. Clin Chem Acta 1985 152 123-34. 

Shemieani R and Rajabi M (2001) Preconcentration of chromium (III) and speciation of chromium by electrothermal atomic absorption spectrometry using cellulose adsorbent. Fresenius J Anal Chem 371 1037-1040. 

Kumpulainen, J., Lehto, J., Koivistoinen, P, Uusitupa, M. and Vuori, E. (1983). Determination of chromium in human milk, serum and urine by electrothermal atomic absorption spectrometry without preliminary ashing. Sci. Tot. Environ., 31, 71. 

Christensen, J.M. and Pedersen, L.M. (1986). Enzymatic digestion of whole blood for improved determination of cadmium, nickel and chromium by electrothermal atomic absorption spectrophotometry Measurements in rheumatoid arthritis and normal humans. Acta Pharmacol. Toxicol. 59, 399-402. 

There are three techniques used for the determination of chromium in tissues and body fluids (1) neutron activation analysis (NAA), (2) isotope dilution mass spectrometry (IDMS), and (3) electrothermal atomic absorption spectroscopy (ETAAS). 

Soares M, Bastos M and Ferreria M (1994) Determination of Total Chromium and Chromium (IV) in Animal Feeds by Electrothermal AAS. J Anal Atom Spectrom 9 1269-1272. 

Flameless atomic absorption using an electrothermal atomiser is essentially a non-routine technique requiring specialist expertise. It is slower than flame analysis only 10—20 samples can be analysed in an hour furthermore, the precision is poorer (1—10%) than that for conventional flame atomic absorption (1%). The main advantage of the method, however, is its superior sensitivity for any metal the sensitivity is 100—1000 times greater when measured by the flameless as opposed to the flame technique. For this reason flameless atomic absorption is employed in the analysis of water samples where the flame techniques have insufficient sensitivity. An example of this is with the elements barium, beryllium, chromium, cobalt, copper, manganese, nickel and vanadium, all of which are required for public health reasons to be measured in raw and potable waters (section I.B). Because these elements are generally at the lOOjugl-1 level and less in water, their concentration is below the detection limit when determined by flame atomic absorption as a result, an electrothermal atomisation (ETA) technique is often employed for their determination. 

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