In atomic absorption spectroscopy, which categories of interference are recognized?

• A. Chemical interference
• B. Ionization/Physical interference
• C. Matrix/ionic interference
• D. All of the above

Answer: (D)

In atomic absorption spectroscopy, interference can arise from several distinct sources that affect how many neutral atoms are available to absorb light. Chemical interference happens when components in the sample form compounds with the analyte or otherwise alter its chemistry in the flame, reducing the amount of free atoms that can be atomized and absorb. Ionization interference occurs when analyte atoms are pushed into the ionized state in the flame, decreasing the population of neutral atoms available to absorb light. Physical interference covers changes in the sample’s physical properties—like viscosity or aerosol transport—or variations in flame conditions that alter atomization and transport, leading to signal fluctuations. Matrix interference describes how the overall composition of the sample matrix affects atomization efficiency and background absorption, requiring calibration approaches that account for the matrix. Since all these interference types are recognized in AAS, the best answer is that all of the above categories are valid.