Clinical Chemistry 6th Edition Bishop by Unknown

Author:Unknown
Language: eng
Format: epub
Tags: book pdf clinical chemistry 6th edition bishop
Published: 2010-04-28T04:00:00+00:00

Impact bead

End cap

FIGURE 17-2. Mixing chamber burner for flame AA. (Courtesy of Perkin-Elmer. Waltham, MA.).

all other emission lines of all other elements. However, there are many cases where emission lines from certain elements overlap the emission lines of certain other elements, resulting in interferences. The choice of interference-free wavelength (atomic or ionic line) may be challenging. While there are several possible wavelengths for a given element, wavelengths producing suitable analytic performance, such as limit of quantitation, freedom from interferences, robustness, etc. are selected.

The first detectors in AES used photographic film. Contemporary AES instruments feature photomultiplier tubes or array-based detector systems.

Atomic Absorption Spectroscopy

Atomic absorption spectroscopy (AAS) is an analytic procedure for the quantitative determination of elements through the absorption of optical radiation by free atoms in the gas phase. The spectra of the atoms are line spectra that are specific for the absorbing elements. Absorption is governed by the Beer-Lambert law:

-log

10

SLCa

(Eq. 17-1)

where A is the absorbance of the sample, I 0 is the incident light intensity, Ij is the transmitted light intensity, s is the molar absorptivity of the target analyte for the wavelength being used, L is the path length, and C g is the gas-phase concentration of the target analyte. Under some simplifying assumptions, this equation takes the form:

A = KC

(Eq. 17-2)

where K is a constant determined by calibration, and C is the solution phase concentration of the analyte.

PART 2 ■ CLINICAL CORRELATIONS AND ANALYTIC PROCEDURES

Light absorption

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