Background correction, atomic absorption spectroscopy

M HNO3. The concentration of Cu and Zn in the diluted supernatant is determined by atomic absorption spectroscopy using an air-acetylene flame and external standards. Copper is analyzed at a wavelength of 324.8 nm with a slit width of 0.5 nm, and zinc is analyzed at 213.9 nm with a slit width of 1.0 nm. Background correction is used for zinc. Results are reported as micrograms of Cu or Zn per gram of FFDT. 

Flameless atomic absorption spectroscopy using the heated graphite furnace is a sensitive method for analyzing environ-mental samples for trace metals. High salt concentrations cause interference problems that are not totally correctable by optimizing furnace conditions and/or using background correctors. We determined that samples with identical ratios of major cations have trace metal absorbances directly related to their Na and trace metal concentrations. Equations and curves based on the Na concentration, similar to standard addition curves, can be calculated to overcome the trace element interference problem. Concentrations of Pb, Cd, Cu, and Fe in sea water can be simply (ind accurately determined from the Na concentration, the sample absorbance vs. a pure standard, and the appropriate curve. 

Figure 20-15 Principle of Zeeman background correction for atomic absorption spectroscopy. (0) In the absence of a magnetic field, we observe the sum of the absorbances of analyte and background, (b) In the presence of a magnetic field, the analyte absorbance Is split away from the hollow cathode wavelength and the absorbance is due to background only, (c) The desired signal is the difference between those observed without and with the magnetic field.

Practically all classical methods of atomic spectroscopy are strongly influenced by interferences and matrix effects. Actually, very few analytical techniques are completely free of interferences. However, with atomic spectroscopy techniques, most of the common interferences have been studied and documented. Interferences are classified conveniently into four categories chemical, physical, background (scattering, absorption) and spectral. There are virtually no spectral interferences in FAAS some form of background correction is required. Matrix effects are more serious. Also GFAAS shows virtually no spectral interferences, but... 

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. 

CONTENTS Preface, Joseph Sneddon. Analyte Excitation Mechanisms in the Inductively Coupled Plasma, Kuang-Pang Li and J.D. Winefordner. Laser-Induced Ionization Spectrometry, Robert B. Green and Michael D. Seltzer. Sample Introduction in Atomic Spectroscopy, Joseph Sneddon. Background Correction Techniques in Atomic Absorption Spectrometry, G. Delude. Flow Injection Techniques for Atomic Spectrometry, Julian F. Tyson. 

S. Smith, R.G. Schleicher, and G.M. Hieftje, New Atomic Absorption Background Correction Technique , Paper 422, 33rd Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, 1982. 

A major difficulty encountered with atomic absorption techniques is the presence of incompletely absorbed background emission from the source and scattered light from the optical system. As the background becomes more intense relative to the absorption of the analyte, the precision of the measurement decreases dramatically. For this reason, several background correction techniques have been implemented. A commonly used method is the method of proximity, which was discussed in relation to inductively coupled plasma spectroscopy. 

Dulude G (1992) Background correction techniques in atomic absorption spectrometry. In Joseph S (ed.) Advances in Atomic Spectroscopy, vol. 1. Amsterdam Elsevier. 

See also Atomic Absorption Spectrometry Principles and Instrumentation Interferences and Background Correction Flame Electrothermal. Atomic Emission Spectrometry Principles and Instrumentation Flame Photometry. Elemental Speciation Practicalities and Instrumentation. Laser-Based Techniques. Optical Spectroscopy Radiation Sources Detection Devices. 

D. How is background correction accomplished in atomic absorption and atomic emission spectroscopy ... 

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