Page 28 - AAS & AES & FES 01082016_Neat

Among the atomic spectral lines that overlap and that can results in spectral interference

are

285.2 nm lines of Tb (Terbium) and Mg (Magnesium)
290.0 nm lines of Cr (Chromium) and Os (Osmium)

422.7 nm lines of Ge (Germanium) and Ca (Calcium)
The easiest way to eliminate a spectral Interference is to use a different spectral line of

the analyte for the assay. A chemical separation prior to the assay can also be used to eliminate

Interference.
Another factor which must be considered while performing assays with flame AAS is

potential difference between the viscosity of the standard and sample solutions. The Viscosity of
the solution affects its rate of aspiration into the flame. More viscous solutions are not aspirated

into the flame as rapidly as less viscous solutions. If the viscosity of the standard is less than that
of the sample, a negative error is introduced into the assay.

Similarly if the viscosity of the standard is more than that of the sample, a positive error

occurs. The viscosity of a solution is determined by the component of the solution. Errors owing
to changes in viscosity can be eliminated by matrix matching, i.e. by preparing the standard in

exactly the same matrix as that of the sample.
Zeeman Background Correction

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 lines for a given transition in place of the single absorption line in the absence of a
magnetic field. This occurs in all atomic spectra and is called Zeeman splitting or the Zeeman

effect.

In the simplest case, the Zeeman effect splits an absorption line into two components.

The first component is the π component, at the same wavelength as before (unshifted); the

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