Electrothermal atomic absorption spectrometry interferences

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. 

M. Felipe-Sotelo, J. M. Andrade, A. Carlosena and D. Prada, Partial least squares multivariate regression as an alternative to handle interferences of Fe on the determination of trace Cr in water by electrothermal atomic absorption spectrometry, Anal. Chem., 75, 2003, 5254 5261. 

This book is rooted in an informal discussion with three researchers. Dr Alatzne Carlosena, Dr Monica Felipe and Dr Maria Jesus Cal, after they had some problems measuring antimony in soils and sediments by electrothermal atomic absorption spectrometry. While we reviewed the results and debated possible problems, much like in a brainstorming session, I realized that some of their difficulties were highly similar to those found in molecular spectrometry (mid-IR spectroscopy, where I had some experience), namely a lack of peak reproducibility, noise, uncontrollable amounts of concomitants, possible matrix interferences, etc. 

The determination of chromium in most biological samples is difficult because of the matrix interference and the very low concentrations present in these samples. Prior to 1978, numerous erroneous results were reported for the chromium level in urine using electrothermal atomic absorption spectrometry (EAAS) because of the inability of conventional atomic absorption spectrometry systems to correct for... 

A modification of the GFAAS method for determining selenium levels in human urine was described by Saeed (1986). In this electrothermal atomic absorption spectrometry (EAAS) method, nitric acid, nickel, and platinum are added to the graphite cell. The addition of nickel helps to mask the spectral interference from phosphates in urine. EAAS has been used to determine selenium levels in human spermatozoa (Suistomaa et al. 1987). 

Radziuk, B. and Thomassen Y. (1992). Chemical modification and spectral interferences in selenium determination using Zeeman-effect electrothermal atomic absorption spectrometry. J. Anal. At. Spectrom., 7, 397. 

Saeed, K. and Thomassen, Y. (1981). Spectral interferences from phosphate matrices in the determination of arsenic, antimony, selenium and tellurium by electrothermal atomic absorption spectrometry. Anal. Chim. Acta 130, 281. 

Electrothermal atomic absorption spectrometry is certainly a method for the determination of arsenic at trace concentration levels. Nevertheless, it has to be stated that this technique must be used carefully as arsenic might be lost during ashing and matrix interferences may occur. An ideal heating program cannot be given without knowledge of the sample composition. 

See also Atomic Absorption Spectrometry Interferences and Background Correction Flame Electrothermal Vapor Generation. Atomic Spectrometry Overview. Flow Injection Analysis Principles. 

Direct measurements of several trace metals by electrothermal atomic absorption spectrometry (ETAAS) have been reported. In general, sensitivities are inadequate for open-ocean waters, though in more metal-enriched environments (e.g., coastal waters and sediment pore waters) such analysis is possible careful corrections for the large and complex salt effects are necessary. The interferences can be minimized by the use of appropriate chemical modifiers, platforms in the graphite tubes, and sophisticated background correction schemes such as Zeeman. 

AAS is the most widely used analytical technique for the determination of lead in biological materials [57,58], The majority of AAS methods employ the electrothermal atomic absorption spectrometry (ETAAS) technique, using either Zeeman background correction or deuterium background correction for the determination of lead in biological fluids [55,59-65], Urine is less often employed as an indicator of exposure however, similar problems associated with AAS determination of lead exist for blood as well as urine (1) incomplete atomization (2) volatile lead salts (3) spectral interferences (4) buildup of carbonaceous residue reducing sensitivity and precision. These analytical problems are eliminated by optimal sample preparation, e,g., dilution, addition of matrix modifiers, deproteinization, and background correction and calibration by matrix-matched standards [66],... 

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). 

J.Y. Cabon and A.L. Bihan. Direct determination of zinc in seawater using electrothermal atomic absorption spectrometry with Zeeman-effect background correction effects of chemical and spectral interferences. Journal of Analytical Atomic Spectrometry 9 477-481,1994. 

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,... 

To avoid problems previously encountered with flame atomic absorption spectrometry of arsenic, and also with flameless methods such as that in which the dementis converted to arsine, Ohta and Suzuki [25] proposed an alternative method based on electrothermal ionisation with a metal microtube atomiser. Effective atomisation can be achieved by the addition of thiourea to the arsenic solution or by preliminary extraction of the arsenic-thionalide complex. The second method is recommended for soil samples so as to avoid interference due to the presence of trace elements. 

The disadvantages of electrothermal atomisation (ETA) — atomic absorption spectrometry (AAS) are the physical, chemical and spectral interferences, these being more severe than with flame atomic absorption spectrometry (FAAS), and which depend critically upon the experimental and operational conditions within the atomiser and the nature of the chemical pretreatment used. It is not intended to discuss here the theoretical aspects of these interferences which have been reviewed excellently elsewhere [2], but it is pertinent to consider briefly how these interferences affect the various stages of the analysis and how they may be minimised. 

Clinical measurements of lithium may be performed using atomic absorption spectrometry (AAS) or flame emission spectrometry (FES) 64). AAS is regarded as the more reliable of the two techniques for blood lithium. FES is rather more sensitive, but suffers from interference from the high sodium and potassium concentrations in blood. Recent developments include inductively coupled plasma (ICP) emission spectrometry, electrothermal atomization atomic absorption spectrometry (ETAAS), and spectrofluorimetric methods. Spectrofluorime-try and ETAAS offer greater sensitivity than the traditional methods and are useful research tools 65, 66). 

Analysis of Al can be routinely performed by inductively coupled plasma (ICP) mass spectrometry (ICP-MS). Alternatively, atomic absorption spectrometry with electrothermal atomization may be employed, but considerable attention must be paid to matrix interferences. 

AAS is split into two types according to the method by which the sample is atomized. In flame atomic absorption spectrometry (FAAS) the sample is aspirated into a flame which is placed in the path ofthe light. In electrothermal atomic absorption (EAAS) the sample is placed in a graphite tube and heated in a brief pulse by passing an electric current through the tube. Generally, EAAS is more sensitive, giving better detection limits, but suffers from more matrix interference effects than FAAS. 

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. 

Byrne,]. P, Chakrabarti, C. L., Gregoire, D. C., Lamoureux, M., and Ly,T. (1992). Mechanisms of chloride interferences in atomic absorption spectrometry using a graphite furnace atomizer investigated by electrothermal vaporization inductively coupled plasma mass spectrometry. Part 1. Effect of magnesium chloride matrix and ascorbic acid chemical modifier on manganese.J. A [Pg.199]

Atomic absorption spectrometry (AAS) has been used to determine cationic and anionic surfactants indirectly. Two methods have been put forward based on the formation of the ion pair between surfactant and hexanitrocobaltate (for cationic compounds) or bis(benzoyl)pyridine thiosemicarbazone cobalt (III) (for anionic compounds). In the former case, the complex is extracted with 1,3-dicloroethane and in the latter with an isopentylacetate and isopentyl alcohol mixture. Concentration of cobalt is determined in the organic phase using electrothermal atomic absorption spectroscopy (ETAAS), while for anionic surfactants, flame atomic absorption spectroscopy (FAAS) can also be used. Interferences like metal ions, anions and organic compounds do not have a great relevance. The two methods were applied to determine dodecyltrimethylammonium bromide in shampoos (Chattaraj and Das, 1992) and sodium lauryl sulfate (SDS) in toothpastes (Chattaraj and Das, 1994). 

---