Transverse heated graphite furnace

Temperature distribution in (a) longitudinally and (b) transversely heated graphite furnace. 

Figure 21-8 (a) Transversely heated graphite furnace maintains nearly constant temperature over its whole length, thereby reducing memory effect from previous runs. The i vov platform is uniformly heated by radiation from the outer wall, not by conduction. The platform is attached to the wall by one small connection that is hidden from view. [Courtesy Perkin-Bmer Corp., Norwalk, Cl] (to) Heating profiles comparing analyte evaporation from wall and from platform. [From W. Slavin, Atomic Absorption Spectroscopy, Anal. Chem. 1982,54,685A.]... 

Gawalko and coworkers elucidated the characteristics of closed-vessel and focused open-vessel MW sample preparation techniques for the subsequent determination of Cd, Cu, and Pb, and Se in wheat, wheat products, corn bran, and rice flour by ET-AAS with transverse-heated graphite furnace [23]. Both techniques were evaluated using a total of 15 CRMs for the three food types. In the case of rice, these were the NIES 10a, 10b, and 10c Rice Flour and the NRC Rice Flour. The two techniques were equivalent in terms of agreement with the certified figures. Up to 12 samples could be processed with the closed system with minimal amounts of acid and reduced risk of contamination. Larger masses of samples could be treated by the open-vessel system. 

E. J. Gawalko, T. W. Nowicki, J. Babb, R. Tkachuk, Comparison of closed-vessel and focused open-vessel microwave dissolution for determination of cadmium, copper, lead, and selenium in wheat, wheat products, corn bran, and rice flour by transverse-heated graphite furnace atom, Int. J. Assoc. Off. Anal. Chem., 80 (1997), 379-387. 

Kumar, S.J., Meeravah, N.N., Arunachalam, J. (1998) Determination of trace impurities in high purity gaUium by inductively coupled plasma mass spectrometry and cross vaUdation of results by transverse heated graphite furnace atomic absorption spectrometry. Analytica Chimica Acta, 371,305-316. 

M.-S. Chan and S.-D. Huang. Direct determination of cadmium and copper in seawater using a transversely heated graphite furnace atomic absorption spectrometer with Zeeman-effect background corrector. Talanta 51 373-380, 2000. 

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. 

Figure 33. Temperature distribution in a longitudinally (left) and transversely (right) heated graphite furnace...

The characteristic mass at the main absorption line, using a transversely heated graphite tube atomizer, is mo = l-6pg. The sensitivity obtained with HR-CS AAS, both in a flame and in the graphite furnace, is significantly better than that with LS AAS. A few less sensitive analytical lines that might be used for the determination of higher rubidium concentrations are compiled in Table 6.22 together with information about their spectral environment. 

AAS = atomic absorption spectrometry EC-THGA = end-capped transversal heating graphite tubes GF-AAS = graphite furnace atomic absorption spectrometry HMA/HMDC = hexamethylene ammonium/hexamethylene dithiocarbamidate LOD = limit of detection... 

The transversely heated furnace (THGA, Fig. 8. IB) avoids many of the problems associated with the longitudinally heated furnace. The graphite tube of a transversely heated... 

Fig. 8.1. Typical graphite furnaces (A) longitudinally heated model, (B) transversely heated model. For details, see text. (Reproduced with permission of Perkin-Elmer.)...

Figure 6.12 A graphite tube for a transversely heated furnace. [Courtesy of PerkinEhner Inc., Shelton, CT (www.perkinehner.com).]...

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