ATOMIC ABSORPTION SPECTROSCOPY
Table of Content
 Introduction..................................................................................................... 02
 History.............................................................................................................. 03
 Principle........................................................................................................... 04
 Components of AAS........................................................................................ 06
1. Atomizer................................................................................................. 06
2. Light Source........................................................................................... 08
3. Monochromator..................................................................................... 08
4. Nebulizer................................................................................................. 09
5. Detector................................................................................................... 10
6. Amplifier................................................................................................. 10
7. Recorder.................................................................................................. 11
 Applications of AAS...................................................................................... 11
1. Quantitative Analysis............................................................................... 11
2. Inorganic Analysis.................................................................................... 12
3. Pollution Monitoring................................................................................ 12
4. Medical Field............................................................................................. 13
5. Biochemical Analysis................................................................................ 13
6. Food and Breveges.................................................................................... 14
7. Material Development.............................................................................. 14
8. Agriculture................................................................................................ 14
9. Geological Analysis................................................................................... 15
10.Forensic Analysis...................................................................................... 15
 Conclusion...................................................................................................... 15
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ATOMIC ABSORPTION SPECTROSCOPY
Atomic Absorption Spectroscopy:
Introduction:
In the past, scientists have done many studies to find out about multiple elements
using a method called atomic absorption spectroscopy.
Atomic Absorption Spectroscopy (AAS) is a method that measures how atoms in a
gas absorb certain kinds of light. This helps scientists see and measure the atoms. The
absorption signal is related to how many free absorbing atoms there are in the light's
path. The first machines used for this were suggested in the 1970s. They used flame
and furnace to work.
AAS can measure over 70 different elements in liquid or solid form. It is used in many
areas like health care, food testing, drug making, mining, and more. The atomic
absorption method is really good for analyzing elements because it doesn't have a lot
of interference and it's specific to each element's energy levels. It's very sensitive and
accurate. The up-to-date version of AAS was created by an Australian Chemist named
Sir Alan Walsh in the 1950s. (Rashid Khan, 2020)
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History:
 In 1665, Newton made the first and most important contribution to the
development of spectroscopy. The colorful sight of a rainbow was the first spread
out spectrum.
 Atomic absorption spectrometry was discovered as a phenomenon in 1802 when
the English scientist William Hyde Wollaston noticed and reported dark lines in
the sun’s spectrum.
 In 1817, the German physicist Josef von Fraunhofer carefully plotted out these
spectral absorption lines, which are today named after him.
 In 1860, the physicists Gustav Kirchhoff and Robert Bunsen established a theory of
spectrochemical analysis. Kirchhoff and Bunsen invented the spectroscope, which
splits light into wavelengths. This approach did not become widely employed until
the 1930s.
 In 1954, a scientist named Alan Walsh built the first atomic absorption
spectrometer. Atomic absorption spectroscopy started in 1955 with the work of
Walsh, Alkemade, and Milatz. Since 1955, the time can be separated into seven-
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year chunks. From 1955 to 1962, only a few people were paying attention to AA
during its early years. (R. Payling and L.C. Lefebvre, 2001)
Principle of Atomic Absorption Spectroscopy:
Atomic absorption spectroscopy is when scientists study how neutral atoms in a flame
absorb radiation in the UV and visible light range.
In atomic absorption spectroscopy, the sample is turned into atomic vapors and then
the absorption of these vapors is measured at a specific wavelength. This method is
also known as absorption flame photometry
The principle of atomic absorption spectroscopy (AAS) is based on the absorption of
light by ground state atoms in the gaseous state. Here's a step-by-step explanation of
the principle:
1. Atomization: The sample is first atomized to convert the elements of interest
into free atoms. This can be achieved using a flame (flame AAS) or a graphite
furnace (graphite furnace AAS). In flame AAS, the sample is introduced into a
flame, where it is vaporized and then atomized into free, gaseous atoms.
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2. Light Source: A hollow cathode lamp (HCL) or other suitable light source emits
light at specific wavelengths corresponding to the characteristic absorption lines of
the element being analyzed. The emitted light typically corresponds to the
electronic transitions within the atoms of the element.
3. Absorption of Light: The light emitted by the lamp passes through the
atomized sample. Atoms of the analyte element absorb light at specific
wavelengths that are characteristic of the element. This absorption occurs because
the electrons in the atoms can be excited from lower energy states to higher energy
states by absorbing photons of light.
4. Measurement of Absorption: A detector measures the intensity of light that
passes through the atomized sample. The detector compares this intensity with the
intensity of the light emitted by the lamp before it passes through the sample. The
absorption of light by the atoms in the sample results in a decrease in the intensity
of certain wavelengths of light.
5. Quantitative Analysis: The amount of light absorbed by the atoms is
proportional to the concentration of the element in the sample.
The absorbance is given by Beer-Lambert’s law; the logarithmic ratio of the intensity
of incident light to the intensity of absorbing species.
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Components of Atomic Absorption Spectroscopy:
The components of the atomic absorption spectroscopy are as follows:
 Atomizer
 Light Source
 Monochromator
 Nebulizer
 Detector
 Amplifier
 Recorder
1. Atomizer:
Atomization is when particles are separated into single molecules and molecules are
broken down into atoms. This is done by heating the substance in a flame or hot
furnace to very high temperatures. To make atoms from a sample, usually two systems
are used. Aspiration means pulling a liquid sample into a flame. Electrothermal
atomization means putting a small amount of sample into a heated graphite tube..
After choosing the right lamp, it is aimed at one or more atomization systems
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ATOMIC ABSORPTION SPECTROSCOPY
Depending on it, AAS is of two types; Flame-AAS, and Electrothermal or graphite
furnace-AAS.
1. Flame Atomization:

Type: Most commonly used in AAS.

Principle: Sample solution is nebulized into fine droplets, which are then carried
into a flame where they are vaporized and atomized.

Flame Types: Typically utilizes an air-acetylene flame or a nitrous oxide-acetylene
flame.

Advantages: Simple to operate, relatively low cost, good sensitivity for many
elements.

Disadvantages: Limited to solutions that can be atomized in a flame, interference
from flame chemistry.
2. Graphite Furnace Atomization:

Type: Also known as Electrothermal atomization or furnace atomization.

Principle: Sample is introduced into a graphite tube that is rapidly heated to
temperatures high enough to vaporize and atomize the sample.

Advantages: Higher sensitivity compared to flame atomization, reduced matrix
effects, can handle smaller sample volumes.

Disadvantages: More complex operation, higher cost, potential memory effects.
(Wiley-VCH, 1999)
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2. Light Source:
We need a steady flow of radiation in the AAS instrument. The very thin absorption
line in the sources creates issues. We used a special lamp to create strong colored lines
for a specific element in a tool that measures how atoms absorb light. The hollow
cathode lamp has two parts inside it. One part is shaped like a cup and made of a
special element. The light from the lamp should not be always on because of
unexpected radiations. So, we used a cutting tool while either radiating or pulsing.
The metal used in the cathode is the same as the metal we studied. The lamp has a gas
inside that doesn't react with other substances and it is not packed too tightly. The light
bulb creates.
 It has a tungsten part and a hollow tube part made of certain elements.
 These are put into a glass tube with a special gas like neon or argon and sealed
shut.
 Each element has its own special lamp that is needed for its analysis. a glowing
light from the inside. (David Harvey, 2008)
3. Monochromator:
In effect a monochromator produces monochromatic light by removing unwanted
wavelength from the source light beam. The function of the monochromator is to
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Isolate a single atomic resonance line from the spectrum of lines emitted by the hallow
cathode lamp.
 This is very important part in a spectrometer. It is used to separate out all of the
thousands of lines
 A monochromator is used to select the specific wavelength of light which is
absorbed by the sample and to exclude the other wavelengths
 The selection of the specific light allows the determination of the selected
element in the presence of others (justin Tom, 2024)
4. Nebulizer:
The nebulizer in Atomic Absorption Spectroscopy (AAS) is a key component
responsible for converting a liquid sample into a fine aerosol or mist of droplets,
which is then introduced into the atomizer for subsequent vaporization and
atomization.
 The primary function of the nebulizer is to introduce the sample solution into
the atomizer. The nebulizer draws the liquid sample from a container and
converts it into a fine spray or mist composed of small droplets.
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ATOMIC ABSORPTION SPECTROSCOPY
 The nebulizer creates an aerosol of sample droplets that is suitable for
introduction into the atomizer.
 The nebulizer helps in minimizing sample matrix effects and interferences by
effectively atomizing the sample into a fine mist. (H. H. Willard, 2009)
5. Detector:
A detector can change light from a monochromator into an electrical signal. Usually,
we use a special tube called a photomultiplier as a detector in the atomic absorption
spectroscopy machine. A detector can be adjusted to react to a certain color. The PMT
is a very sensitive detector used in atomic absorption spectrometers.
The light from the monochromator goes into the PMT and hits a photodiode, which
then turns it into an electrical signal. The first electric signal will be made stronger by
a series of dynodes and then it is gathered
6. Amplifier:
The electric current from the photomultiplier locator is nourished to the speaker which
intensifies the electric current a few times
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7. Recorder:
The recorder takes electrical signals from the detector and changes them into a
response that can be read. Today, we used a computer system with the right software
to record signals from the detector in atomic absorption spectroscopy.
Applications of Atomic Absorption Spectroscopy:
Atomic absorption spectrometry is a very important tool for finding tiny amounts of
metallic elements.
This method is used to measure about 60 different metals. Atomic absorption
spectrometry can be used to analyze chemicals in all areas. Atomic absorption
spectroscopy is a commonly used method in many fields such as chemistry, ceramics,
mineralogy, biochemistry, metallurgy, water supply, medicine, and soil analysis.
1. Quantitative Analysis:
Quantitative analysis is about figuring out how much radiation the sample has
absorbed. This measurement shows how many atoms in the light path can soak up the
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light. However, we can't figure out how much of the element is in the sample just by
counting how many atoms are in the atomizer. In real life, we often need to calibrate
instruments to take accurate measurements.
Calibration curves are made by using a solution with a known amount of the element
in the sample. The sample is broken down into tiny particles like the standard, and its
amount is figured out using the calibration curve. Atomic absorption spectroscopy is a
method used to measure the amount of different metal elements. (Báez, 2005)
2. Inorganic and Metallurgical analysis:
The types of minerals and rocks found in an area can tell us if it’s worth mining there.
After digging up the ores and minerals, we need to check what they are made of before
we can refine them properly. Also, checking for small amounts of metals is very
helpful in finding where there might be oil or water underground.
We used a special machine called atomic absorption spectrometry to find small
amounts of metals in different kinds of samples like rocks, animals, metals, glass,
cement, oil, sea dirt, medicine, and air. It is also used to find small amounts of
elements in soil, water, rocks, minerals, and more. Atomic absorption spectroscopy
looks at small and light metals using light. Atomic absorption spectroscopy is also
used to find out the amount of Co, Cr, Mg, Mn, Pb, Zn, and other elements in iron and
steel. (Mishra, 2018)
3. Pollution Monitoring:
It is very important to check for harmful metals in the air, water, and industrial waste
to make sure it's safe for living things.
Atomic absorption spectrometry is used to find pollutants in the environment, like lead
in the air and arsenic in water underground. (Mishra A. C., 2009)
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4. Medical Field:
We use a method called Atomic absorption spectrometry to find out the levels of Ca,
Mg, Na, and K in the blood.
Atomic absorption spectroscopy is a method used to analyze blood and find out the
levels of sodium, potassium, iron, copper, zinc, and lead.
Atomic absorption spectroscopy is a test that looks at hair and nails to figure out the
levels of certain compounds like Co, Zn, Mg, Pb, Cu, and Fe.
Atomic absorption spectroscopy is used to test for metals in food.
Atomic absorption spectroscopy is used to test for metals in petroleum and oil. (Ali,
2009)
5. Biochemical Analysis:
AAS is used to quantify essential trace elements (e.g., iron, zinc, copper) in biological
fluids (e.g., blood serum, urine, saliva) and tissues. This analysis helps in assessing
nutritional status, identifying deficiencies or excesses, and understanding the role of
these elements in metabolic processes.
AAS enables the measurement of toxic elements (e.g., lead, cadmium, mercury) in
biological samples, providing insights into environmental exposure and potential
health risks.
AAS can be used to investigate the role of trace elements in enzyme function and
metabolic pathways. It aids in understanding the impact of trace element deficiencies
or imbalances on enzymatic activity and cellular processes.
AAS is employed to study the uptake, transport, and distribution of metal ions (e.g.,
calcium, magnesium) in cells and tissues. This helps elucidate cellular signaling
pathways and physiological responses related to metal ion homeostasis. (J.B.Wills,
1963)
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6. Food and Beverages:
AAS is utilized to measure essential trace elements (e.g., iron, zinc, copper) in food
products such as grains, fruits, vegetables, and dairy products. AAS is employed to
detect and quantify toxic heavy metals (e.g., lead, cadmium, mercury) in food and
beverage samples. AAS enables the analysis of minerals and micronutrients (e.g.,
calcium, magnesium, selenium) in fortified foods, supplements, and infant formula.
AAS is used to detect trace elements present in food due to environmental factors
(e.g., arsenic, selenium) or processing contaminants. AAS is applied to analyze metal
content in beverages such as water, juice, beer, and wine. (Dickson, 2012)
7. Material Development:
AAS is used to analyze the elemental composition of metals and alloys during
manufacturing processes. AAS aids in evaluating the thickness and composition of
metal coatings (e.g., zinc plating, chrome coating) applied to substrates. AAS is
employed to quantify trace elements (e.g., arsenic, gallium) in semiconductor
materials such as silicon wafers. AAS assists in analyzing metal catalysts used in
chemical processes (e.g., catalytic converters, industrial reactions). (Aquisman, 2014)
8. Agriculture:
AAS is employed to determine the concentration of essential nutrients (e.g.,
potassium, calcium, magnesium) and trace elements (e.g., iron, zinc, manganese) in
soil samples. AAS is used to analyze the elemental composition of plant tissues (e.g.,
leaves, stems, roots) to diagnose nutrient deficiencies or toxicities.
AAS assists in analyzing the nutrient content of fertilizers (e.g., nitrogen, phosphorus,
potassium) and assessing the presence of trace contaminants (e.g., heavy metals). AAS
is applied to analyze the elemental composition of irrigation water, particularly
assessing the levels of essential nutrients (e.g., calcium, magnesium) and potential
contaminants (e.g., sodium, boron). (Cuffari, 2018)
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9. Geological Studies:
AAS is used to analyze rock and mineral samples for trace elements associated with
ore deposits (e.g., gold, silver, copper). AAS enables the systematic analysis of
geological samples (e.g., soil, sediment) to generate geochemical maps of mineral
distribution and elemental anomalies. AAS is employed in mining operations to
monitor metal concentrations in ore samples and assess ore grade variability.
(Balaram, 2022)
10. Forensic Analysis:
AAS enables elemental profiling and comparison of materials (e.g., glass fragments,
metallic residues) to establish forensic associations and provide corroborative
evidence. AAS is used in forensic geology to analyze trace metal profiles in soil and
environmental samples collected from crime scenes. AAS assists in detecting trace
metal elements (e.g., lead, chromium) in ink samples for forensic document analysis
AAS is employed to analyze trace elements in jewelry, glass fragments, and other
trace evidence to establish forensic associations. (GUPTA, 2020)
Conclusion:
Atomic absorption spectroscopy (AAS) is a helpful tool for analyzing metals in a
sample. It can give accurate and precise information about what elements are in the
sample. AAS can find tiny amounts of metals, like in parts per million or even parts
per billion. It can also figure out what elements are in a sample by comparing it to a
database. AAS has four main parts: a light source, an atomizer, a monochromator, and
a detector. AAS works by checking how much light is taken in by the sample at
certain wavelengths that match the energy difference between the basic and excited
states of the atoms. To make sure AAS works well and gives accurate results, it needs
to be regularly checked and adjusted. AAS is a useful tool that can be used in many
different areas like medicine, farming, factories, and scientific studies.
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