Atomic absorption spectroscopy (AAS) measures the absorption of specific wavelengths of light by free atoms to determine analyte concentration. Key components include a radiation source, atomizer, monochromator, detector, and signal processor, while interferences can arise from spectral and chemical factors. AAS is widely used in pharmaceuticals for trace metal analysis, environmental monitoring, and clinical applications, offering high sensitivity but being limited to metals and susceptible to matrix interferences.

1. Atomic Absorption Spectroscopy
(AAS)
Principle, Instrumentation,
Interferences, and Applications
VISHAL PAWAR
MODERN PHARMACEUTICAL ANALYTICAL
TECHNIQUES (MPAT 101T)

2. Principle of Atomic Absorption
Spectroscopy
• Atomic Absorption Spectroscopy (AAS) is
based on the principle that free atoms in the
ground state absorb light of specific
wavelengths.
• Key Points:
• - Atoms absorb radiation at characteristic
wavelengths (resonance).
• - Absorbance is proportional to the analyte
concentration.

3. Instrumentation: Components of
AAS (1/2)
• 1. Radiation Source:
• - Hollow Cathode Lamp (HCL) emits light
specific to the analyte.
• 2. Atomizer:
• - Converts the sample into free atoms.
• - Types: Flame Atomizer and Graphite Furnace
Atomizer.

4. Instrumentation: Components of
AAS (2/2)
• 4. Monochromator:
• - Isolates the specific wavelength absorbed by
the analyte.
• 5. Detector:
• - Photomultiplier tube detects light intensity.
• - Converts light signals to electrical signals.
• 6. Signal Processor:

5. Interferences in Atomic Absorption
Spectroscopy
• 1. Spectral Interferences:
• - Overlapping absorption/emission lines.
• - Solution: Use a narrow-band
monochromator or background correction.
• 2. Chemical Interferences:
• - Formation of refractory compounds.
• - Solution: Add releasing agents or increase
flame temperature.

6. Applications of Atomic Absorption
Spectroscopy
• 1. Pharmaceutical Industry:
• - Analysis of trace metals in drugs and APIs.
• - Quality control and heavy metal detection.
• 2. Environmental Monitoring:
• - Detection of heavy metals in water, soil, and
air.
• 3. Clinical Applications:

7. Advantages and Limitations of AAS
• Advantages:
• - High sensitivity and specificity.
• - Fast and precise analysis for trace elements.
• - Cost-effective and versatile.
• Limitations:
• - Limited to metals and metalloids.
• - Requires separate lamps for each element.
• - Susceptible to matrix interferences.

8. References
• 1. Skoog, D. A., Holler, F. J., & Crouch, S. R.
(2007). Principles of Instrumental Analysis.
• 2. Willard, H. H., Merritt, L. L., Dean, J. A., &
Settle, F. A. (1981). Instrumental Methods of
Analysis.
• 3. ICH Q3D Guidelines on Elemental
Impurities.
• 4. Dasgupta, P. K., & Cullen, T. (2014).
Analytical Chemistry: A Modern Approach.