Continuum-source atomic absorption spectrometry

Figure 21-19 Graphite furnace absorption spectrum of bronze dissolved in HN03. [From B. T. Jones. B. W Smith, and J. D. Winetordner. Continuum Source Atomic Absorption Spectrometry in a Graphite Furnace with Photodiode Array Detection. Anal. Chem. 1989,61. 1670.]...

H. Becker-Ross, S. Florek, U. Heitmann, R. Weisse, Influence of the spectral bandwidth of the spectrometer on the sensitivity using continuum source atomic absorption spectrometry, Fresenius J. Anal. Chem., 355 (1996), 300. 

Welz B, Becker-Ross H, Florek S, Heitmann U, Vale MGR. Braz J. High-resolution continuum-source atomic absorption spectrometry - what can we expect Chem Soc 2003 14 220-9. 

Historical Development of Continuum Source Atomic Absorption Spectrometry... 

D.L.G. Borges, Direct determination of Lead in Biological Samples by High-Resolution Continuum Source Atomic Absorption Spectrometry, Master thesis, Uni-versidade Federal de Santa Catarina, Florianopolis, Brazil, 2005. 

A.F. Silva, D.L.G. Borges, F.G. Lepri, B. Welz, A.J. Curtius, U. Heitmann, Determination of cadmium in coal using solid sampling graphite furnace high-resolution continuum source atomic absorption spectrometry, calibration against aqueous standards and Ir as a permanent modifier, J. Anal. Atom. Spectrom. (2005) submitted. 

Continuum-source atomic absorption spectrometry in the case of a high-... 

ScHUETZ M., Murphy J., Fields R. F. and Haenly J. M. (2000) Continuum source-atomic absorption spectrometry using a two-dimensional charge-coupled device, Spectrochim. Acta, Part B 55 1895-1912. 

Florek S. and Heitmann U. (2002) Investigation of interferences in the determination of thallium in marine sediment reference materials using high-resolution continuum-source atomic absorption spectrometry and electrothermal atomization, Spectrochim. Acta, Part B 57 1043—1055. 

U. Heitmann, S. Florek, M. D. Huang, Sensitivity, linearity and working range of a modem continuum-source atomic absorption spectrometer, Seventh Rio Symposium on Atomic Spectrometry, Book of Abstracts, Florianopolis, SC, Brazil, 7-12 April 2002,... 

J.A. Rust, J.A. Nobrega, C.P. CaUoway Jr., and B.T. Jones. Advances with tungsten coil atomizers continuum source atomic absorption and emission spectrometry. Spectrochimica Acta Part B 60 589-598, 2005. 

Atomic Fluorescence Spectrometry. A spectroscopic technique related to some of the types mentioned above is atomic fluorescence spectrometry (AFS). Like atomic absorption spectrometry (AAS), AFS requires a light source separate from that of the heated flame cell. This can be provided, as in AAS, by individual (or multielement lamps), or by a continuum source such as xenon arc or by suitable lasers or combination of lasers and dyes. The laser is still pretty much in its infancy but it is likely that future development will cause the laser, and consequently the many spectroscopic instruments to which it can be adapted to, to become increasingly popular. Complete freedom of wavelength selection still remains a problem. Unlike AAS the light source in AFS is not in direct line with the optical path, and therefore, the radiation emitted is a result of excitation by the lamp or laser source. 

Welz, B., D.L. Borges, F.G. Lepri, M.G.R. Vale, and U. Heitmann. 2007. High-resolution continuum source electrothermal atomic absorption spectrometry—an analytical and diagnostic tool for trace analysis. Spectrochim. Acta B 62 873-883. 

J. M. Harnly, The future of atomic absorption spectrometry a continuum source with a charge coupled array detector, J. Anal. Atom. Spectrom., 14 (1999), 137. 

A. S. Ribeiro, M. A. Vieira, A. F. Silva, D. L. G. Borges, B. Welz, U. Heitmann, A. J. Curtius, Determination of cobalt in biological samples by line-source and high-resolution continuum source graphite furnace atomic absorption spectrometry using solid sampling or alkaline treatment, Spectrochim. Acta, 60B (2005), 693. 

The most important radiation sources in atomic absorption spectrometry are the hollow cathode lamps and electrodeless discharge lamps. Other sources which have been used are lasers, flames, analytical plasmas, and normal continuum sources like deuterium and xenon arc lamps. 

Atomic absorption spectrometry (AAS) has been widely used. Although flame AAS was useful in the past [45], electrothermal AAS is now preferred [30,46-48] as well as a simultaneous multielement atomic absorption continuum source coupled with a carbon furnace atomizer (SIMAAC) [49] or inductively coupled plasma atomic emission spectrometry (ICPAES) [39]. 

Resano, M., Briceno, J., Belarra, M.A. (2009) Direct determination of Hg in polymers by means of sohd samphng— graphite furnace atomic absorption spectrometry. A comparison of the performance of line source and continuum source instrumentation. Spectrochim. Acta Part B, 64, 520-529. 

B. Welz, S. Mores, E. Carasek, M. G. R. Vale, M. Okruss and H. Beeker-Ross, High-resolution continuum source atomic and molecular absorption spectrometry - a review, Appl. Spectrosc. Rev., 2010, 45, 327-354. 

M. Resano, L. Rello, M. Florez and M. A. Belarra, On the possibilities of high-resolution continuum source graphite furnace atomic absorption spectrometry for the simultaneous or sequential monitoring of multiple atomic lines, Spectrochimica Acta, Part B, 2011, 66, 321-328. 

Quartz tube (QT) atomisation and high-resolution continuum source hydride generation atomic absorption spectrometry (FIR-CS HG-AAS) were used to determine lead. A full two-level factorial design characterised the effects of the reagent concentrations. The experimental conditions were determined using a Box-Behnken design. 

S. L. C. Ferreira, D. C. Lima, I. T. A. Moreira and O. M. C. de Oliveira, Critical study using experimental design of the determination of lead by high-resolution continuum source hydride generation atomic absorption spectrometry, J. Anal. At. Spectrom., 2011, 26(10), 2039-2044. 

D. C. Baxter, W. Freeh and I. Berglund, Use of partial least squares modelling to compesate for spectral interferences in electrothermal atomic absorption spectrometry with continuum source background correction,... 

Dittert, I.M., Silva, J.S.A., Araujo, R.G.O., Curtius, A.J., Welz, B., Becker-Ross, H., (2010), Simultaneous determination of cobalt and vanadium in imdiluted crude oil using high resolution continuum source graphite furnace atomic absorption spectrometry. /, Anal. At. Spectrom. 25, 590-595. 

Lepri, F.G., Welz, B., Borges, D.L.G., Silva, A.F., Vale, M.G.R., Heitmann, U., (2006), Speciation analysis of volatile and nonvolatile vanadium compounds in Brazilian crude oils using high resolution continuum source graphite furnace atomic absorption spectrometry. Anal. Chim. Acta, 558,195-200. 

Atomic fluorescence spectrometry has a number of potential advantages when compared to atomic absorption. The most important is the relative case with which several elements can be determined simultaneously. This arises from the non-directional nature of fluorescence emission, which enables separate hollow-cathode lamps or a continuum source providing suitable primary radiation to be grouped around a circular burner with one or more detectors. 

Atomic fluorescence flame spectrometry is receiving increased attention as a potential tool for the trace analysis of inorganic ions. Studies to date have indicated that limits of detection comparable or superior to those currently obtainable with atomic absorption or flame emission methods are frequently possible for elements whose emission lines are in the ultraviolet. The use of a continuum source, such as the high-pressure xenon arc, has been successful, although the limits of detection obtainable are not usually as low as those obtained with intense line sources. However, the xenon source can be used for the analysis of several elements either individually or by scanning a portion of the spectruin. Only chemical interferences are of concern they appear to be qualitatively similar for both atomic absorption and atomic fluorescence. With the current development of better sources and investigations into devices other than flames for sample introduction, further improvements in atomic fluorescence spectroscopy are to be expected. 

Molecular absorption spectrometry (MAS) is based on the formation of stable, volatile two-atomic compounds in the atomization cell, and the molecular absorption of the compound formed is then measured at the absorption band by means of a continuum or a line-like radiation source. These methods are described in the next section (6.7). 

Fig. 2.3. Absorbance as a function of optical density for selected shock tube investigations employing OH electronic absorption spectrometry. The unmarked curve represents the semi-empirical relationship derived in Reference 37, evaluated at a pressure (5 1 atm) and temperature (1520 K) typical of recombination experiments in an argon diluent. Tlie curves labelled 6 1, 3 1 and 1 3 were empirically determined over a selected range of recombination pressures and temperatures for mixtures dilute in argon with those particular initial H2/O2 ratios (Reference 32). The curve identified by HJ (Reference 24) was empirically determined in a 1 % Hg-l % 02-98 % Ar mixture at 1300 K for a selected range of pressures. The cross-hatched area represents the approximate range of absorbances and optical densities observed with an atomic bismuth line source (Reference 41). Also shown are the line HH derived from photographic spectroscopy using instrumental definition of absorption line centres on a continuum (Reference 48), and a solid circle (beyond the range of the abscissa) denoting the photoelectric absorbance reported in Reference 47 for a continuum source at an optical density of 750 x 10" moles liter cm.

---