Graphite furnace background correction

Nowka R, Muller H (1997) Direct analysis of solid samples by graphite furnace atomic absorption spectrometry with a transversely heated graphite atomizer and D2-background correction system (SS GF-AAS). Fresenius J Anal Chem 359 132-137. 

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. 

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]. 

Grobenski et al. [709] have reviewed methodology for the determination of these elements in seawater. Zeeman-effect background correction using an AC magnet around the graphite furnace corrects for nonspecific attenuation up to 2.0 absorbance and corrects for structured background. 

Maximum power heating, the L vov platform, gas stop, the smallest possible temperature step between thermal pretreatment and atomisation, peak area integration, and matrix modification have been applied in order to eliminate or at least reduce interferences in graphite furnace AAS. With Zeeman effect background correction, much better correction is achieved, making method development and trace metal determinations in samples containing high salt concentrations much simpler or even possible at all. 

Zong, Y. Y., Parsons, P. J., and Slavin, W. (1998). Background correction errors for lead in the presence of phosphate with Zeeman graphite furnace atomic absorption spectrometry. Spectrochimica Acta B 53 1031-1039. 

In the method described by Willie et al. [167] atomic absorption measurements were made with a Perkin-Elmer 5000 spectrometer fitted with a Model HGA 500 graphite furnace and Zeeman effect background correction system. Peak absorbance signals were recorded with a Perkin-Elmer PRS-10 printer-sequencer. A selenium electrodeless lamp (Perkin-Elmer Corp.) operated at 6W was used as the source. Absorption was measured at the 196.0nm line. The spectral band-pass was 0.7nm. Standard Perkin-Elmer pyrolytic graphite-coated tubes were used in all studies. 

Application of this principle is used in two types of background absorption correction set-up. Single beam atomic absorption instruments have an electromagnet at the level of the graphite furnace (or flame) and a polariser in the optical path (Fig. 14.14). However, this accessory is quite expensive. 

Dube P. 1988. Determination of chromium in human urine by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction. Analyst 113 917-921. 

Apparatus Use a suitable spectrophotometer (Perkin-El-mer Model 6000, or equivalent), a graphite furnace containing a L vov platform (Perkin-Elmer Model HGA-500, or equivalent), and an autosampler (Perkin-Elmer Model AS-40, or equivalent). Use a lead hollow-cathode lamp (lamp current of 10 mA), a slit width of 0.7 mm (set low), the wavelength set at 283.3 nm, and a deuterium arc lamp for background correction. 

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