I am shanmugapriya. my first seminar on AAS. soon I will upload my second seminar on DLS. you can comment about my presentation it will help me lot

1. BY
I.G.Shanmugapriya
Junior Research Fellow
C/O , Dr. Rohit Kumar Rana,
Nanomaterials Laboratory,
CSIR-IICT, Hyderabad.
Dr. ALAN WALSH
1

2. CONTENTS
 Introduction
 Application of AAS
 Techniques in AAS
 Instrumentation
 Analytical feature of AAS
 Assurance of analytical results
 Comparative studies
2

3. what is the difference between
absorption & emission?
what is the difference between
spectroscopy & spectrometry?
what is the difference between atomic
spectroscopy & molecular
spectroscopy?
3

4. ATOMIC EMISSION ATOMIC ABSORPTION
4

5.  Qualitative and Quantitative analysis
of metal, non-metal, metalloids in the solution.
To detect metals such as
Aluminium (Al) Copper (Cu) Mercury(Hg)
Antimony (Sb) Gallium (Ga) Molybdenum (Mo)
Arsenic (As) Hafnium (Hf) Nickel (Ni)
Beryllium (Be) Indium (In) Niobium (Nb)
Barium (Ba) Iron (Fe) Ruthenium (Ru)
Calcium (Ca) Lead (Pb) Tin (Sn)
Chromium (Cr) Lithium (Li) Tungsten (W)
Cadmium (Cd) Magnesium (Mg) Vanadium (V)
Cobalt (Co) Manganese (Mn) Zinc (Zn) & Zirconium(Zr)
Gold (Au) Silver (Ag) Copper (Cu)
5

6. AAS

7.  Flame AAS (FAAS)- for higher concentration
of analyte (mg/mL)
 Electro thermal AAS (ET AAS) or Graphite furnace
AAS (GF AAS) – for trace or ultra trace
concentration of analyte (pg/mL) to (ng/mL)
 Vapour generation Techniques (VG AAS)
 Hydride generation AAS (HG AAS) – for trace
concentration of As,Se,Sb,Te,Sn….
 Cold vapour AAS - for trace concentration of Hg
7

8. FOUR Basic Components
• Light source
• Nebulizer
• Atomizers
• Specific light
measurements
 Monochromator
 Detector
 Amplified read out -
recorder
8

10. 1. HOLLOW CATHODE LAMP
2. ELECTRODELESS DISCHARGE LAMP
3. DEUTERIUM LAMP
LINE SOURCE
(HIGH INTENSITY)
CONTINUUM SOURCE
1. HIGH PRESSURE
XENON LAMP
10

11. Hollow Cathode Lamp (HCL) For Metals
11

12. Deuterium Lamp- UV radiation
12

13. Electrodeless discharge lamp {EDL}
1.To analyse volatile elements
As,Sb,Bi,Cd,Hg,Rb,Sn,Te,etc. EDL
is more intense than HCL results
into high precision and lower
detection limit.
2. Sputtering of metal atoms
and their adsorption on
cathode lamp walls and
windows begins to affect the
lamp on other hand EDL
because of high emission
intensity overcome the problem
easily.
3. High cost compare to HCL
13

14. Xenon lamp

15. HIGH RESOLUTION CONTINUUM SOURCE OF
ATOMIC ABSORPTION SPECTROMETER (hr-cs aa
spectrometer)
15

17. Nebulizer
1.Suck up liquid sample at a
controlled rate.
2. Creates a fine aerosol for
introduction into flame.
3. Mixes the aerosol and fuel
and oxidant thoroughly for
introduction into the flame.
4. The smaller the size of the
droplets produced, the higher
the element sensitivity.
17

18. Flame process
18

19. Sample Atomization Technique
1. Flame atomization
2. Electrothermal atomization
3. Hydride atomization
4. Cold vapour atomization
ATOMIZER
DISCRETE CONTINUOUS
FLAME
ELECTRO
THERMAL
ELECTROTHERMAL ATOMIZATION
19

20. Pros Cons
High sensitivity because
samples are atomised quickly
Analyte can diffuse into
graphite so need to replace
Small size sample also small
amount required for analysis
Cost wise expensive
Solution, slurries, solid
compound also analysed
Detection limit is 100 ppb to 1
ppb
Reduced spectral interference
because of graphite furnace
Analyte may be lost at ashing
stage
More efficient atomization
compare to flame atomization
Slow measurement time
DRYING ASHING ATOMIS
ATION
20

21. FLAME ATOMIZATION Pros Cons
Easy to use Only solution can be
analysed
Inexpensive Large sample quantity
required
High precision Limit of detection
between 1 ppm for
Transition metals to 10
ppm for alkali metals
Reproducible for all liquid
samples
Oxides leads to decrease
the absorbance of sample
Long length of analytical
time
Lower sensitivity
21

22. COLD VAPOUR ATOMIZATION
For Hydride forming elements
Like As, Sb, Se…
As (V)
(sol)
NaBH4
[H+] AsH3 As (gas)+H2Heat
In flame
HYDRIDE ATOMIZATION
HgCl2+SnCl2 ` Hg+SnCl4
Mercury cannot be atomised by
flame or furnace . In this technique
mercury acidified and reduced and
swept through by stream of inert
gas . Absorbed gas determined.
22

23. DETECTOR
Detector converts light signals to electrical
signals
Ideal detector should have fast response times,
linear response over a wide range of wavelength
with low noise and high sensitivity.
Types of detector available for AAS
1. Photomultiplier Tube
2. Photodiode
Charge Coupled Devise
(CCD)
Photodiode Array
23

24. Charge Coupled Devise (CCD)
24

25.  Sensitivity
a slope of calibration line; sensitivity in F AAS is indirectly expressed as
characteristic concentration (i.e. such concentration [μg/ml] of the element that
gives the absorbance of 0.0044); characteristic mass [pg] is used to characterize
analytical sensitivity in GF AAS.
 Detection limits
in F AAS approx. 2 to 5 times lower than characteristic concentration.
 Working range
approx. 2 to 3 orders of magnitude (a narrower range in GF AAS).
 Repeatability
in F AAS under optimum conditions RSD 0.5-1.5 %; RSD in GF AAS ranges
approx. from 1 to 5 %.
 Accuracy, trueness
especially in GF AAS accuracy can be affected by the sample matrix
(e.g via analyte transport, formation of thermally stable compounds, non-
atomic absorption).
25

26.  Appropriate calibration
 Optimization of fuel-oxidant gas composition (in F AAS)
 Optimization of all steps of the atomizer temperature
programme (in GF AAS)
 Selection of suitable matrix modifier for electro thermal
atomization
 Optimization of burner height (in F AAS)
 Addition of suitable reagents (releasing or deionizing) to
the samples in necessary cases (in F AAS).

28. 28

29. while there are some
applications better
suited to one or
another of the
techniques based on
the element to be
analysed.
example:
1. Rare earth elements
analysis is easier with
quadrupole ICP-MS,
whereas sulfur analysis
is better done with ICP
or magnetic sector
ICP-MS
29

30. www.chemistry.nmsu.edu/Instrumentation/AAS_Nebulizer.html
http://weather.nmsu.edu/Teaching_Material/soil698/Student_Reports/Spectroscopy/nebulizer.html
http://faculty.sdmiramar.edu/fgarces/LabMatters/Instruments/AA/AAS_Instrument/AASInstruments.html
Boss, C.B. and Freden, K.J. Concepts, Instrumentation and Techniques in Inductively
Coupled Plasma Optical Emission Spectrometry. 1997
Skoog, D. Fundamentals of Analytical Chemistry, 2004
Ma, G. and Gonzales, G.B. Flame Atomic Absorption Spectrometry.
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