Electrothermal atomization applications

The scope of this review Is limited to electrothermal atomic absorption spectrometry, with emphasis upon Its clinical applications. This article Is Intended to supplement the recent treatises on the basic technique which have been written by Aggett and Sprott ( ) > Ingle ( ), Klrkbrlght (34), Price (63), and Woodrlff (83). This resume does not consider various related topics, such as (a) atomic fluorescence or emission spectrometry (b) non-flame atomization devices which employ direct current... 

In Table I are listed comprehensive citations of published methods for analyses of trace metals In body fluids and other clinical specimens by means of electrothermal atomic absorption spectrometry. Readers are cautioned that many of the early methods that are cited In Table I have become outmoded, owing to Improvements In Instrumentation for electrothermal atomic absorption spectrometry. All of the published methods need to be critically evaluated In the prospective analyst s laboratory before they can be confidently employed for diagnostic measurements of trace metals In body fluids. Despite these caveats, the author believes that Table I should be helpful as a guide to the growing literature on clinical and biological applications of electrothermal atomic absorption spectrometry. 

The literature on applications of electrothermal atomizers is now extremely large and, because of the details of the furnace programmes used, is well worth consulting. The tables in the Atomic Spectrometry Updates reports (see Appendix C) offer the best way of accessing this information. 

Q. Why is electrothermal atomization widely used in clinical applications ... 

I. Arambarri, R. Garcia and E. Millan, Application of experimental design in a method for screening sediments for global determination of organic tin by electrothermal atomic absorption spectrometry (ETAAS), Fresenius J. Anal. Chem., 371(7), 2001, 955-960. 

B. Do, S. Robinet, D. Pradeau and F. Guyon, Speciation of arsenic and selenium compounds by ion-pair reversed-phase chromatography with electrothermal atomic absorption spectrometry. Application of experimental design for chromatographic optimisation, J. Chromatogr. A, 918(1), 2001, 87-98. 

Using palladium-magnesium nitrate mixtures as chemical modifiers, Hinds and Jackson [114] effectively delayed the atomisation of lead until atomic absorption spectrometer furnace conditions were nearly isothermal. This technique was used to determine lead in soil slurries. Zhang et al. [115] investigated the application of low-pressure electrothermal atomic absorption spectrometry to the determination of lead in soils. 

AMS = accelerated mass spectroscopy EDTA = ethylene diamine tetra acetic acid GFAAS = graphite furnace atomic absorption spectrometry ICP-AES = inductively coupled plasma - atomic emission spectroscopy NAA = neutron activation analysis ETAAS = electrothermal atomic absorption spectrometry SEC/ICP-MS = size-exclusion chromatography/ICP-AES/mass spectrometry HLPC/ICP-AES = high-performance liquid chromatography/ICP-AES LAMMA = laser ablation microprobe mass analysis NA = not applicable ppq = parts per quadrillion... 

Miscellaneous. Trace analyses have been performed for a variety of other materials. Table 9 lists some uses of electrothermal atomic absorption spectrometry (etaas) for determination of trace amounts of elements in a variety of matrices. The applications of icp/ms to geological and biological materials include the following (165) ... 

It is worth stressing that everything that has ever been published on the application of AAS to food analysis can be done at least as well with HR-CS AAS. Since the same flames and burners, and the same type of electrothermal atomizers, are used in both systems, and only the spectrometer part from the radiation source to the detector has been re-designed, it is much more appropriate to talk about the improvements brought about by this change, and about the simplifications and the additional features that have become available this way. 

K. G. Fernandes, M. de Moraes, J. A. Gomes Neto, J. A. Nobrega, Evaluation and application of bismuth as an internal standard for the determination of lead in wines by simultaneous electrothermal atomic absorption spectrometry, Analyst, 127 (2002), 157-162. 

The requirement for calibrated laboratory-ware for containing and dispensing solutions extends to all facets of the analytical procedure. It rests with the analyst to ascertain accuracy suitable to the application, of all devices used, including micropipets used in conjunction with electrothermal atomizers. The temptation to use other than appropriately calibrated containers, and chemical reagents of suitably high purity, and not to follow good analytical procedures as practised by those with only peripheral contact with analytical chemistry, should be avoided. 

Detection techniques of high sensitivity, selectivity, and ease of coupling with sample preparation procedures are of special interest for measuring PGM content in biological and environmental samples. ICP MS, electrothermal atomic absorption spectrometry (ET AAS), adsorptive voltammetry (AV), and neutron activation analysis (NAA) have fotmd the widest applications, both for direct determination of the total metal content in the examined samples and for coupling with instrumental separation techniques. Mass spectrometry coupled with techniques such as electrospray ionization (ESI) and capillary electrophoresis (CE) (e.g., ESI MS", LC ESI MS", LC ICP MS, CE MS", and CE ICP MS) offer powerful potential for speciation analysis of metals. MS is widely used for examination of the distribution of the metals in various materials (elemental analysis) and for elucidation of the... 

As noted earlier, USNs have been employed for sample insertion into atomic spectrometers suoh as flame atomio absorption spectrometry (FAAS) [9,10], electrothermal atomic absorption speotrometry (ETAAS) [11], atomic fluorescence spectrometry (AFS) [12,13], induotively ooupled plasma-atomic emission spectrometry (ICP-AES) [14,15], inductively coupled plasma-mass spectrometry (ICP-MS) [16,17] and microwave induced plasma-atomic emission spectrometry (MIP-AES) [18,19]. Most of the applications of ultrasonic nebulization (USNn) involve plasma-based detectors, the high sensitivity, selectivity, precision, resolution and throughput have fostered their implementation in routine laboratories despite their high cost [4]. 

Volynsky A. B. (1998) Applications of graphite tubes modified with high-melting carbides in electrothermal atomic absorption spectrometry I. General approach, Spectrochim Acta, Part B 53 509-535. 

Krivan V., Barth P. and Schnurer-Patschan C. (1988) An electrothermal atomic absorption spectrometer using semiconductor diode lasers and a tungsten coil atomizer design and first applications, Anal Chem 70 3625-3632. 

Pyrolysis can also be used in flow-based determinations with electrothermal atomic absorption spectrometry, as demonstrated in the determination of nickel in environmental and biological reference materials using a sequential injection system with renewable beads [313]. After analyte sorption, the beads were directed towards the furnace of the spectrometer and stopped there pyrolysis was accomplished as usual in order to release the analyte and destroy the beads. This innovation has often been exploited in the lab-on-valve system, but spectrophotometric applications have not been proposed to date. 

Some specific applications are tabulated in Table 2.7, presenting examples of applications of flame atomic absorption spectro-metric analytical techniques to elemental determinations in a variety of materials, while Table 2.8 lists examples of applications of electrothermal atomic absorption spectrometric analytical techniques. 

Cobalt ultra-trace On-line preconcentration and determination using a PTFE turnings packed column and electrothermal atomic absorption spectrometry. Applications in natural waters and biological samples. J Anal Atom Spectrom 17 1330-1334. 

Teissedre PL, Cabanis MTand Cabanis JC (1993) [Comparison of two mineralization methods for the determination of lead by electrothermal atomic absorption spectrometry. Applications to soils, vine-leaves, grapes, musts, rapes and lees samples]. Ana-lusis 21 249 - 254 [French]. 

In the 1980s, research has been performed on laser-induced AFS (LI-AFS) after electrothermal atomization of metals. No application of this technique for the determination of mercury seems to have appeared, but for several other metals, detection limits 1-2 orders of magnitude lower than for GF-AAS have been reported (Dougherty et al., 1989 Ome-netto, 1989, general review). However, the application of this technique on mercury in biological samples may cause problems, due to the volatility of mercury compounds (see Graphite furnace ). 

The introduction of atomic absorption spectrometry in 1955 by Walsh has brought about a preferred analytical technique among clinical chemists in the field of element determinations. Flame atomic absorption atomization techniques with solution aspiration is not sufficiently sensitive (detection limits varies from 0,05-3 mg Se/L for most clinical applications where sub-mg/L concentrations are encountered. The sensivity can, however, be improved by generation of volatile selenium hydride and subsequent atomization in argon-hydrogen flames or electrically heated quartz tubes. Electrothermal atomization of solutions in graphite tubes has developed rapidly since the analytical use was first proposed and studied by L vov (1961). For most clinical chemists this technique may be the most appropriate technique to analyze samples for low concentrations of selenium. 

Gardiner, P.E., Ottaway, J.M., Fell, G.S. and Burns, R.R. (1981). The application of gel filtration and electrothermal atomic absorption spectrophotometry to the speciation of protein bound zinc and copper in human biood serum. Anal. Chim. Acta, 124, 281. 

Oua/itative and Semiquantitative Applications Because ICPMS is easily adapted to multielement analyses, it is well suited to the rapid characterization and semiquantitative analysis of various types of naturally occurring and manufactured complex materials. Generally, detection limits arc better than those for optical emission ICP and compete with detection limits for electrothermal atomic absorption spectroscopy. 

ETAAS. In ETAAS atomization takes place in an electrothermal atomizer which is heated to the appropriate temperature programme. The detection limits of the method are about two or three orders of magnitude better than FAAS. It is applicable to about 40 elements but generally for about 20 elements detection limits at the ng and pg level can be reached. Commensurable or better sensitivities have only INAA, ICP-MS and stripping voltammetry. Therefore ETAAS is widely used for environmental analysis. However the method suffers from serious interferences leading to systematic errors due to thermochemical processes in the atomizer. Background absorption is also a potential source for systematic errors. Spectral interferences are additive and cannot be corrected by the popular standard addition method. ETAAS is also not free of memory effects for refractory elements. 

See alsa Atomic Absorption Spectrometry Electrothermal. Atomic Emission Spectrometry Flame Photometry. Cadmium. Carbon. Chemiiuminescence Overview. Fluorescence Environmental Applications. Gas Chromatography Environmental Applications. Laser-Based Techniques. Lead. Nitrogen. Ozone. Polycyclic Aromatic Hydrocarbons Environmental Applications. Remote Gas Sensing Overview. Spectrophotometry Inorganic Compounds. Sulfur. X-Ray Fluorescence and Emission X-Ray Fluorescence Theory. 

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