Atomic Absorption Spectroscopy (AAS) and atomic emission spectroscopy (AES) is a spectroanalytical technique for rapid trace metal analysis. AAS methods are based on the absorption of light by free metallic ions.

1. Source: Atomic Absorption Spectroscopy (AAS) - medium.com
What is Atomic Absorption Spectroscopy?
Atomic Absorption Spectroscopy (AAS) and atomic emission
spectroscopy (AES) is a spectroanalytical technique for rapid trace metal
analysis. AAS methods are based on the absorption of light by free metallic
ions.
The atomic absorption spectroscopy instrument is used for determining the
concentration of a particular element or analyte in a sample to be analyzed.
ATOMIC ABSORPTION SPECTROSCOPY (AAS)

2. It can be used to identify 70 different elements in solution or directly in
solid samples through electrothermal vaporization. The technique is used
widely in pharmacology, biophysics, archaeology, and toxicology research.
Atomic absorption spectrometry has wide uses in medicinal chemistry for
the analysis of metals in biological fluids and tissues such as whole blood,
plasma, urine, saliva, brain tissue, liver, hair, and muscle tissue.
Instrumentation of AAS
Any atomic emission spectroscopy (AAS) instrument is composed of the
following three main components:

3. Atomizer
Atomization is an important step in AAS and the atomizer is an important
component of AAS instruments. It can be carried out either by a flame or
furnace. Heat energy is used to convert the metallic element to atomic
dissociated vapour.
The temperature should be controlled carefully to convert it to an atomic
state because at too high or too low a temperature, atoms will be ionized
and will not be absorbed. Flame and electrothermal atomizers are two
commonly used atomizers for AAS instruments.
Radiation Source
There is a radiation source in AAS that irradiates the atomized sample. The
analyzed sample absorbs some of the radiation, and the rest passes through
the spectrometer to a detector. Line sources and continuum sources are two
radiation sources in the AAS instrument.
Atomizer
Radiation Source
Spectrometer
Detector

4. Line sources excite the analyte and provide its own line spectrum.
Continuum sources provide the spectrum over a wider range of
wavelengths.
Spectrometer
A spectrometer in AAS instruments is used to differentiate between various
types of wavelengths of light before they pass to the detector. The
spectrometer in the AAS instrument can be either single-beam or double-
beam.
The radiation is directed through the atomized sample in single-beam
spectrometers but double-beam spectrometers require two beams of light
— one beam that passes directly through the sample, and another that does
not pass through the sample at all.
Detector
A detector in AAS is a mechanical, chemical, or electrical device that
measures the change of a variable in its environment. The most common
detector in atomic absorption spectrometer (AAS) is the photomultiplier
tube (PMT).
Applications of AAS
Atomic absorption spectroscopy (AAS) provides cost-effective solutions for
the analysis of trace amounts of metals from geological samples,

5. environmental samples, biological specimens, agricultural products and
soils, pharmaceuticals, foods, and drinking water.
 The elemental composition of geological samples (minerals and rocks)
provides important information on commercial refining operations.
After mining, the ores and minerals may be tested by an AAS instrument
for determining their composition.
 Environmental monitoring for trace metal contamination by atomic
absorption spectroscopy (AAS) from industrial effluents, oceans, rivers,
and lakes gives important data about the safety of drinking water and
water that use for commercial purposes.
 AAS analysis provides the composition of materials that significantly
influenced some common properties of such as hardness, brittleness,
grain size, crystallinity, and amorphous nature.
 AAS analysis plays an important role in formulation development,
catalyst efficiency, and dosage limits in the pharmaceutical industry.
Most elements have a beneficial role up to certain prescribed limits but
beyond such limits, many serious side effects are caused by these
elements.
 Food safety is increasing day by day. Food manufacturers have to ensure
that trace metals do not exceed the permissible limits. Therefore, the
foods and beverages industry uses atomic absorption spectroscopy and
other sophisticated instruments for ensuring their quality.

6.  The constitution of soils and their acidic or basic nature is essential for
productivity and nutrient value. AAS analysis on plants gives a fair idea
of how the uptake of minerals gets distributed under different growth
conditions.
 Atomic absorption spectroscopy (AAS) analysis provides valuable
information on specimens collected from the scene of a crime.
References
 Atomic Absorption Spectroscopy — Instrumentation, Principle —
Priyamstudycentre.com
 Atomic absorption spectroscopy — Wikipedia
 Atomic Absorption Spectrometry (AAS) Information —
thermofisher.com