Atomic absorption spectrometry electrothermal

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

INDIRECT DETERMINATION OF ASCORBIC ACID BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY... 

COMPARISON OF MICROWAVE ASSISTED EXTRACTION METHODS FOR THE DETERMINATION OF PLATINUM GROUP ELEMENTS IN SOIL SAMPLES BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY AFTER PHASE SEPARATION-EXTRACTION... 

Lead in soil slurries Electrothermal atomic absorption spectrometry... 

Electrothermal Atomic Absorption Spectrometry of Trace Metals in Biological Fluids... 

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... 

Inadequate regulation of atomizer temperature Is a major source of Imprecision In electrothermal atomic absorption spectrometry. The programmed heating of electrothermal atomizers can be achieved by five different methods, depending upon the electrical or physical parameters which are monltorled during... 

Micro-pipetting instruments such as the "Eppendorf or "Oxford pipettors with disposable plastic cone tips are customarily employed to dispense the liquid samples into electrothermal atomizers. Sampling problems which are associated with the use of these pipettors are among the troublesome aspects of electrothermal atomic absorption spectrometry (67,75). The plastic cone-tips are frequently contaminated with metals, and they should invariably be cleaned before use by soaking in dilute "ultra pure nitric acid, followed by multiple rinses with demineralized water which has been distilled in a quartz still. 

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. 

N1 and Zn from a graphite rod were significantly lower than from a tantalum filament, suggesting that these free metal atoms can be liberated by chemical reduction of their respective oxides, rather than by direct thermal dissociation. Findlay et al (19) emphasized the hazards of preatomlzatlon losses of trace met s In electrothermal atomic absorption spectrometry, when the ashing temperature Is permitted to exceed the minimum temperature for vaporization of the analyte. 

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. 

Inductively coupled plasma atomic emission spectrometry Electrothermal atomic absorption spectrometry High pressure liquid chromatography... 

P. Van Keerbergen, J. Smeyers-Verbeke and D.L. Massart, Decision support system for run suitability checking and explorative method validation in electrothermal atomic absorption spectrometry. J. Anal. Atomic Spectrom. inch Atomic Spectrom. Updates, 11 (2) (1996) 149-158. 

Brown SS, Nomoto S, Stoeppler M, Sunderman FW Jr (1981) lUPAC reference method for analysis of nickel in serum and urine by electrothermal atomic absorption spectrometry. Clin Biochem 14 295-299. 

Acar 0, Kn ic Z, Turker AR (1999) Determination of bismuth, indium and lead in geological and sea-water samples by electrothermal atomic absorption spectrometry with nickel containing chemical modifiers. Anal Chim Acta 382 329-338. 

Eaton AD, Clesceri LS, Greenberg AE. 1995c. Method 3113, Metals by Electrothermal Atomic Absorption Spectrometry, Standard Methods for the Examination of Water and Wastewater, American Public Health Association, Washington, DC. 

Xu Y, Liang Y. 1997. Combined nickel and phosphate modifier for lead determination in water by electrothermal atomic absorption spectrometry. Journal of Analytical Atomic Spectrometry 12(4) 471-474. 

Electrothermal atomic absorption spectrometry is used to study the total arsenic and arsenic (III) content in marine sediments [64]. 

Shijo et al. [95] converted bismuth in seawater into its dithiocarbamate complex, and then extracted the complex into xylene prior to determination in amounts down to 0.3 ppt by electrothermal atomic absorption spectrometry. 

Atomic absorption spectrometry has been used to determine caesium in seawater. The method uses preliminary chromatographic separation on a strong cation exchange resin, ammonium hexcyanocobalt ferrate, followed by electrothermal atomic absorption spectrometry. The procedure is convenient, versatile, and reliable, although decomposition products from the exchanger, namely iron and cobalt, can cause interference. 

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. 

To determine down to 2.4 xmol/l of copper in seawater, Nishoika et al. [282] complexed the copper with di-ethyl-dithio carbamate, precipitated with ferric hydroxide, filtered off and dissolved the precipitate with nitric acid, and determined copper by electrothermal atomic absorption spectrometry. 

A typical measurement was performed as follows. The feeder was lowered into the crucible and the sample solution (seawater) was allowed to flow under an inert atmosphere with the suction on. A constant current was applied for a predetermined time. When the pre-electrolysis was over, the flow was changed from the sample to the ammonium acetate washing solution, while the deposited metals were maintained under cathodic protection. Ammonium acetate was selected for its low decomposition temperature, and a 0.2 ml 1 1 concentration was used to ensure sufficient conductivity. At this point the feeder tip was raised to the highest position and the usual steps for an electrothermal atomic absorption spectrometry measurement were followed drying for 30 s at 900 C, ashing for 30 s at 700 °C, and atomization for 8 s at 1700 °C, with measurement at 283.3 nm. The baseline increases smoothly with time as a consequence of an upward lift of the crucible caused by thermal expansion of the material. 

Jin [666] used ammonium pyrrolidine dithiocarbamate and electrothermal atomic absorption spectrometry to determine lead, cadmium, copper, cobalt, tin, and molybdenum in seawater. 

Chakraborti et al. [665] determined cadmium, cobalt, copper, iron, nickel, and lead in seawater by chelation with diethyldithiocarbamate from a 500 ml sample, extraction into carbon tetrachloride, evaporation to dryness, and redissolution in nitric acid prior to determination by electrothermal atomic absorption spectrometry in amounts ranging from 10 pg (cadmium) to 250 pg (nickel). 

Cimadevilla et al. [691] compared wall, platform, and graphite furnace probe atomisation techniques in electrothermal atomic absorption spectrometry for the determination of ig/l levels of silver, cadmium, and lead in seawater. 

Chang et al. [952] used a miniature column packed with a chelating resin and an automatic online preconcentration system for electrothermal atomic absorption spectrometry to determine cadmium, cobalt, and nickel in seawater. Detection limits of 0.12,7 and 35 ng/1 were achieved for cadmium, cobalt, and nickel, respectively, with very small sample volume required (400-1800 xl). 

---