Inductively coupled plasma atomic theory

Flame atomic absorption was until recently the most widely used techniques for trace metal analysis, reflecting its ease of use and relative freedom from interferences. Although now superceded in many laboratories by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry, flame atomic absorption spectrometry still is a very valid option for many applications. The sample, usually in solution, is sprayed into the flame following the generation of an aerosol by means of a nebulizer. The theory of atomic absorption spectrometry (AAS) and details of the basic instrumentation required are described in a previous article. This article briefly reviews the nature of the flames employed in AAS, the specific requirements of the instrumentation for use with flame AAS, and the atomization processes that take place within the flame. An overview is given of possible interferences and various modifications that may provide some practical advantage over conventional flame cells. Finally, a number of application notes for common matrices are given. 

While a deviation from a straight line calibration is often predictable in principle from physical theory, a quantitative account is usually lacking there is no known reason why a true calibration graph should be a quadratic function or higher order polynomial. Indeed they are often of a somewhat different shape. This leads to a degree of lack of fit between the true function and the fitted function. Figure 2.23 shows an example, where a quadratic function has been fitted to closely spaced data of the slightly different shape typical of inductively coupled plasma atomic emission spectroscopy (ICP-AES) calibrations. 

GFAAS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES - also referred to as inductively coupled plasma-optical emission spectroscopy, or ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) are all routinely utilized in pharmaceutical applications. While there are other techniques of note available, such as micro-wave induced plasma (MIP) or direct coupled plasma (DCP), they have not been routinely used in the pharmaceutical industry, and will, therefore, not be discussed here. The theories involved in the use of FAAS, GFAAS, ICP and ICP-MS may be found in other articles of this Encyclopedia. 

After this brief review of theory, let us turn our attention to existing practice, as exemplified In environmental methods of analysis. Environmental methods of analysis employ many of the common analytical Instruments In analyzing a wide spectrum of chemicals In a variety of matrices. Instruments commonly used Include spectrophotometers (atomic absorption, visible. Inductively coupled plasma), gas chromatographs (with a variety of detectors. Including the mass spectrometer), and automatic analyzers. 

O Connor, C., Sharp, B.L., Evans, P. (2006) On-line additions of aqueous standards for cahbration of laser ablation inductively coupled plasma mass spectrometry theory and comparison of wet and dry plasma conditions./oMrnaZ of Analytical Atomic Spectrometry,21, 556-565. 

See also Atomic Absorption, Methods and Instrumentation Atomic Absorption, Theory Atomic Emission, Methods and Instrumentation Biomedical Applications of Atomic Spectroscopy Forensic Science, Applications of Atomic Spectroscopy Hyphenated Techniques, Applications of in Mass Spectrometry Inductively Coupled Plasma Mass Spectrometry, Methods Inorganic Chemistry, Applications of Mass Spectrometry. 

See also Electronic Components, Applications of Atomic Spectroscopy Fluorescence and Emission Spectroscopy, Theory Inductively Coupled Plasma Mass Spectrometry, Methods. 

Haswell SJ (ed) (1991) Atomic Absorption Spectrometry Theory, Design and Applications. Amsterdam Elsevier. Thompson M and Walsh JN (1989) Handbook of Inductively Coupled Plasma Spectrometry, 2nd edn. Glasgow Blackie. 

Emission, Methods and Instrumentation Atomic Fluorescence, Methods and Instrumentation Fluorescence and Emission Spectroscopy, Theory Geology and Mineralogy, Applications of Atomic Spectroscopy Inductively Coupled Plasma Mass Spectrometry, Methods Proton Microprobe (Method and Background) X-Ray Emission Spectroscopy, Applications X-Ray Emission Spectroscopy, Methods X-Ray Fluorescence Spectrometers X-Ray Spectroscopy, Theory. 

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