Electrothermal atomic absorption 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. 

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) ... 

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. 

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]. 

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. 

Electrothermal atomic absorption spectrometry (ETAAS) has been the single most important technique in advancing our knowledge of the transition metal distribution in seawater. The graphite-furnace mode is used most frequently. It has the advantage of high sensitivity and therefore small sample volume (e.g., 10-50//L). Major disadvantages are the matrix interferences which usually necessitate a pre-concentration and/or a separation step (see Sections 12.2.1 and 12.2.2). Another application of ETAAS is the cold-vapour technique for the determination of mercury (Section 12.2.4). 

For the majority of applications, the sample is taken into solution and introduced into the plasma as an aerosol in the argon stream. The sample solution is pumped by a peristaltic pump at a fixed rate and converted into an aerosol by a nebulizer (see atomic absorption spectrometry). Various designs of nebulizer are in use, each having strengths and weaknesses. The reader is directed to the more specialist texts for a detailed consideration of nebulizers. There is an obvious attraction in being able to handle a solid directly, and sample volatilization methods using electric spark ablation, laser ablation and electrothermal volatilization have also been developed. 

Atomic absorption spectrometry has been applied to the analysis of over sixty elements. The technique combines speed, simplicity and versatility and has been applied to a very wide range of non-ferrous metal analyses. This review presents a cross section of applications. For the majority of applications flame atomisation is employed but where sensitivity is inadequate using direct aspiration of the sample solution a number of methods using a preconcentration stage have been described. Non-flame atomisation methods have been extensively applied to the analysis of ultra-trace levels of impurities in non-ferrous metals. The application of electrothermal atomisation, particularly to nickel-based alloys has enabled the determination of sub-part per million levels of impurities to be carried out in a fraction of the time required for the chemical separation and flame atomisation techniques. 

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