Atomic Absorption Spectroscopy: Interference

AAS measurements may encounter spectral, chemical, or physical interferences that obscure or change the magnitude of the detected analyte signal.

Spectral interference occurs when a signal from an interferent or the atomization flame overlaps with the analyte's signal, falsely elevating or masking the analyte's absorbance.

This can be addressed using Zeeman, Smith–Hieftje, or deuterium background correction techniques. In addition, high-resolution spectrometers can minimize spectral interference from overlapping spectral lines. 

Sources of chemical interference include analyte interactions with matrix constituents, producing nonvolatile salts that lower atomization efficiency.

Such interference can be avoided using high atomization temperatures or by adding complexing or releasing agents.

Furthermore, some atomic analytes may ionize during the analysis, resulting in reduced absorption. However, adding a more easily ionized element suppresses the ionization of the analyte.

Physical interferences arising from non-chemical factors, like variations in gas flow rates or flame temperature, are minimized through frequent calibration, internal standards, or the addition of known quantities of analyte into the sample.