Background correction Zeeman

Atomic absorption lines occur at discrete wavelengths because the transition that gives rise to the absorption is between two discrete energy levels. However, when a vapor-phase atom is placed in a strong magnetic field, the electronic energy levels split. This gives rise to several absorption 

The %- and o-components respond differently to polarized light. The x-component absorbs light polarized in the direction parallel to the magnetic field. The o-components absorb only radiation polarized 90° to the applied field. The combination of splitting and polarization differences can be used to measured total absorbance (atomic plus background) and background only, permitting the net atomic absorption to be determined. 

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Ellen G, Van Loon JW. 1990. Determination of cadmium and lead in foods by graphite furnace atomic absorption spectrometry with Zeeman background correction Test with certified reference materials. Food Addit Contam 7 265-273. 

Chapters 5 and 6 discuss the application of new techniques such as atomic absorption spectrometry with and without graphite furnace and Zeeman background correction, inductively coupled plasma mass spectrometry, X-ray fluo-... 

Many of the published methods for the determination of metals in seawater are concerned with the determination of a single element. Single-element methods are discussed firstly in Sects. 5.2-5.73. However, much of the published work is concerned not only with the determination of a single element but with the determination of groups of elements (Sect. 5.74). This is particularly so in the case of techniques such as graphite furnace atomic absorption spectrometry, Zeeman background-corrected atomic absorption spectrometry, and inductively coupled plasma spectrometry. This also applies to other techniques, such as voltammetry, polarography, neutron activation analysis, X-ray fluroescence spectroscopy, and isotope dilution techniques. 

Pruszkowska et al. [135] described a simple and direct method for the determination of cadmium in coastal water utilizing a platform graphite furnace and Zeeman background correction. The furnace conditions are summarised in Table 5.1. These workers obtained a detection limit of 0.013 pg/1 in 12 pi samples, or about 0.16 pg cadmium in the coastal seawater sample. The characteristic integrated amount was 0.35 pg cadmium per 0.0044 A s. A matrix modifier containing di-ammonium hydrogen phosphate and nitric acid was used. Concentrations of cadmium in coastal seawater were calculated directly from a calibration curve. Standards contained sodium chloride and the same matrix modifier as the samples. No interference from the matrix was observed. 

Electrothermal atomic absorption spectrophotometry with Zeeman background correction was used by Zhang et al. [141] for the determination of cadmium in seawater. Citric acid was used as an organic matrix modifier and was found to be more effective than EDTA or ascorbic acid. The organic matrix modifier reduced the interferences from salts and other trace metals and gave a linear calibration curve for cadmium at concentrations < 1.6 pg/1. The method has a limit of detection of 0.019 pg/1 of cadmium and recoveries of 95-105% at the 0.2 pg of cadmium level. 

Graphite furnace atomic absorption spectrometry with the L vov platform and Zeeman background correction has been applied to the determination of down to 0.02 xg/l manganese in seawater [452]. 

Knowles M (1987) Varian atomic absorption no AA 71 methods for the determination of cadmium in seawater with Zeeman background correction... 

Guillard 0, Tiphaneau K, Reiss D, et al. 1984. Improved determination of aluminum in serum by electrothermal atomic absorption spectrometry and zeeman background correction. Anal Lett 17 1593-1605. 

Serum and urine HN03 de-proteinization GFAAS with pyrolytic graphite tube and Zeeman background correction 0.02 pg/L (serum) 0.1 pg/L (urine) No data Sunderman et al. 1989... 

Zeeman background correction also depends upon line splitting, but in this instance most commonly the absorption line profile (the n component) is split into two or more components (the a components) by the application of an intense... 

F. J. Fernandez, M. M. Beaty, Elimination of spectral interferences in the determination of Se in nickel-base alloys using Zeeman background correction, Spectrochim. Acta, 39B (1984), 519. 

The direct determination of Fe and Se by ET-AAS was proposed without any digestion, that is, just by simple dilution of the milk samples [68, 69, 74]. The elements were determined in bovine milk after dilution of the sample with water-soluble tertiary amines (10 percent). Pyrolytic graphite tubes, Pd as the chemical modifier, and Zeeman background correction were used. The concentration of Fe varied from 0.61 to 1.17 mg l-1 and Se concentrations were in the 17-122 pg l-1 range. 

Zn by using the cobalt dithiocarbamate co-precipitation and back extraction (14) method. The blanks underwent a similar procedure. Both blanks and sample extracts were analyzed with a Hitachi 180-80 atomic absorption spectrophotometer, equipped with Zeeman background correction. The method of standard additions was used to correct matrix effects during analysis. The analytical conditions during the experiment were those recommended by the vendor (15). 

For the homogeneity and stability studies, the trace element contents (Cd, Cr, Cu, Ni, Pb and Zn) were determined by flame atomic absorption spectrometry (FAAS) or electrothermal atomic absorption spectrometry with Zeeman background correction (ZETAAS), strictly following the sequential extraction procedure. Differences between the within-bottle and between-bottle CVs observed for the step 2 were considered to be rather an analytical artefact than an indication of inhomogeneity which would have been reflected in the spread of results submitted in the certification. The material is then considered to be homogeneous for the stated level of intake (1 g). 

For the homogeneity studies, the extractants (0.05 mol L EDTA, 0.43 mol L" acetic acid and 0.005 mol L DTPA) were prepared as laid out in the certification reports [15, 17], The trace element contents (Cd, Cr, Cu, Ni, Pb and Zn) in the extracts were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) for the CRMs 483/484, flame atomic absorption spectrometry (FAAS) or electrothermal atomic absorption spectrometry with Zeeman background correction (ZETAAS) for the CRM 600. In the case of the CRM 483, little analytical difficulty was experienced as illustrated by the good agreement obtained between the within-bottle and between-bottle CVs for the CRM 484, lower extractable contents, closer to the detection limits and consequent poorer analytical precision was observed in particular for Cr (EDTA extractable contents), Cd and Pb (acetic acid extractable contents). No particular difficulties were experienced for the CRM 600. On the basis of these results, the materials were considered to be homogeneous at a level of 5 g for EDTA- and acetic acid-extractable contents and 10 g for DTPA-extractable contents (as specified in the extraction protocols). 

The techniques of final determination are summarised in Table 11.1. Sample pretreatment methods were e.g. dry ashing or pressurised digestion with combination of acids. Techniques such as ICP-AES or ETAAS with Zeeman background correction were not yet popular at the time of the certification campaign [8]. 

ZETAAS ETAAS with Zeeman background correction... 

Serum Dilute sample with matrix modifier containing Mg(N03)2 and Ni(N03)2 to thermally stabilize Se heat, dry, atomize use Zeeman background correction ZAAS No data 6.2% relative standard deviation Lewis et al. 1986b... 

Lewis SA, Hardison NW, Veillon C. 1986. Comparison of isotope dilution mass spectrometry and graphite furnace atomic absorption spectrometry with Zeeman background correction for determination of plasma selenium. Anal Chem 58 1272-1273. 

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