Interferences in AAS can broadly be classified into three categories:
1. Spectral Interferences:
These occur when another species in the sample absorbs light at the same or nearby wavelengths as the analyte.
Overlapping absorption lines and stray light from the source can be common reasons for spectral interferences.
2. Chemical Interferences:
These happen when the chemical form of the analyte is changed, often preventing it from reaching the atomized state, or when another species in the sample reacts with the analyte.
Matrix elements might cause precipitation or complexation of the analyte.
The nature of the flame (oxidizing or reducing) can affect the atomization of the analyte.
3. Physical Interferences:
These are typically related to the sample matrix affecting the atomization efficiency or light transmission.
Viscosity, refractive index, and surface tension of the solution can cause issues in nebulization or mist formation.
Dust or other particulate matter can scatter light.
