1. Graphite Furnace Atomic Absorption
Spectroscopy
Presented By:
Anuradha verma
M.Sc (1st Sem)

2. CONTENTS
What is GFAAS
Working of GFAAS
Advantages of GFAAS
Disadvantages of GFAAS
Applications

3. What is GFAAS
Graphite furnace atomic absorption spectrometry
(GFAAS) (also known as Electro thermal Atomic
Absorption spectrometry (ETAAS)) is a type
of spectrometry that uses a graphite-coated
furnace to vaporize the sample.
Instead of employing the high temperature of a
flame to bring about the production of atoms
from the sample and it is non-flame methods
involving electrically heated graphite tubes or
rods.

4. Working of GFAAS
•Aqueous samples should be acidified (typically with nitric acid, HNO3) to a
pH of 2.0 or less. Discoloration in a sample may indicate that metals are
present in the sample. For example, a greenish color may indicate a high
nickel content, or a bluish color may indicate a high copper content. A good
rule to follow is to analyze clear (relatively dilute) samples first, and then
analyze colored (relatively concentrated) samples. It may be necessary to
dilute highly colored samples before they are analyzed.
•After the instrument has warmed up and been calibrated, a small aliquot
(usually less than 100 microliters (µL) and typically 20 µL) is placed, either
manually or through an automated sampler, into the opening in the graphite
tube.
•The graphite furnace is an electrothermal atomizer system that can produce
temperatures as high as 3,000°C. The heated graphite furnace provides the
thermal energy to break chemical bonds within the sample and produce free
ground-state atoms. Ground-state atoms then are capable of absorbing
energy, in the form of light, and are elevated to an excited state.
Contd....

5. •The sample is vaporized in the heated graphite tube; the amount of light
energy absorbed in the vapour is proportional to atomic concentrations.
• The free atoms will absorb light at frequencies or wavelengths characteristic
of the element of interest .
• Within certain limits, the amount of light absorbed can be linearly correlated
to the concentration of analyte present.

6. Instrumentation
Schematic representation of working

7. Simple Schematic
Working

8. Graphite furnace AAS
Sample holder: graphite tube
Samples are placed directly in the
graphite furnace which is then
electrically heated.
Beam of light passes through the tube
Three stages:
1. drying of sample
2. ashing of organic matter (to burn off organic species that would
interfere with the elemental analysis.
3. vaporization of analyte atoms

9. Flame AAS
Disadvantages
 relatively large sample
quantities required (1 – 2
mL)
 less sensitivity (compared
to graphite furnace)
 problems with refractory
elements
N.B.-Refractory elements:
Resisting the action of heat;
very difficult to melt or fuse.
Advantages
 inexpensive (equipment,
day-to-day running)
 high sample throughput
 easy to use
 high precision
N.B.-Throughput:
The amount of material put
through a process, esp. in
manufacturing or computing.
Also, processing or handling
capacity.

10. Advantages of GFAAS
Greater sensitivity and detection limits
(hundred- or thousand fold improvements in the
detection limit compared with flame AAS) than
other methods.
Direct analysis of some types of liquid
samples.
Some solid sample do not require prior
dissolution.
Low spectral interference.
Very small sample size (as low as 0.5µL).

11. Disadvantages of GFAAS
expensive
low precision
low sample throughput
requires high level of
operator skill

12. Applications of GFAAS
GFAA has been used primarily for analysis of low
concentrations of metals in samples of water. The
more sophisticated GFAAs have a number of lamps
and therefore are capable of simultaneous and
automatic determinations for more than one element.
for the quantification of beryllium in blood and
serum.

13. Thank You