Atomic Absorption spectrometry

1. ATOMIC
ABSORPTION
SPECTROMETRY

2. SPECTROMETRY
Defined as
measurement of
intensity of light at
selected wavelength
Widely used method of
Quantitative and
Qualitative analysis

3. Types of spectrometry
Visible
Spectrophotometer
Ultraviolet-visible
spectrophotometer
Infrared
spectrophotometer
Flourescence
Spectrophotometer
Atomicc absorption
spectrophotometer
Atomic emission
spectrophotometer

4. AAS
Introduced by Alan
Walsh in 1955
Used for mining, medical
treatment and agriculture

5. Introduction
Commonly used to detect metals and metalloids in sample like
Aluminium Copper Lithium Magnesium Zinc etc
Used to measure concentration by detecting absorption of
electromagnetic radiation by atom rather than by molecules

6. Elements detectable by atomic absorption in the periodic table

7. PRINCIPLE
Technique in which a metallic atom in the sample absorbs light of a specific wavelength
Element is merely atomized and placed in a ground state
This ground state absorbs radiation at a bandwidth corresponding to it’s own line spectrum
A hollow cathode lamp with the cathode made of material to be analysed is used to produce a wavelength of
light specific for atom
When light from the cathode lamp enters the flame, some of it is absorbed by ground state atoms in the flame,
resulting in net decrease in intensity of beam from lamp
This process is called atomic absorption
Concentration measurements are determined after calibrating the instrument with standards of known
concentration

9. Components
Light Source Chopper Atomizer Monochromator Detector

10. Light Source
•A hollow cathode lamp cathode made
of material to be analyzed is used to produce a
wavelength of light specific for the atom
• It usually contains argon or neon gas at a pressure
of a few millimeters of mercury.

11. CHOPPER
A rotating wheel interposed between hollow cathode lamp and flame
It breaks steady light into pulsating light which is used to measure intensity of
light absorbed by elements without interference by radiaytion from flame itself
Pulsting light gives pulsating current in photocell
There is also steady current caused by light which is emitted by flame. But only
pulsating current is amplified and recorded

12. Atomizer
• Atomization is separation of particles into individual
molecules and breaking molecules into atoms.
• This is done by exposing the analyte to high temperatures in
a flame or graphite furnace
• Flame - air acetylene is used to generate flame
• Graphite tube - The graphite coated tubes are heated by high
current supply
Nebulizer
• Sucks up liquid at controlled rate & creates fine aerosol that
is mixed with the fuel & oxidant for introduction in to the flame

13. Monochromator
This is a very important part in an AA spectrometer.
A monochromator is used to select the specific wavelength of light
which is absorbed by the sample, and to exclude other wavelengths.
The selection of the specific light allows the determination of the
selected element in the presence of others.

14. Detector
Light selected by the monochromator - detector
(photomultiplier tube)
Which converts light signal into an electrical signal
proportional to the light intensity.
The processing of electrical signal is fulfilled by a signal
amplifier .

15. Calibration curve
•Calibration - known solutes
•Calibration curve of concentration vs absorbance is plotted.
•The absorbance of the element in this solution is measured .
•The unknown concentration of the element is then calculated from
the calibration curve

16. TYPES OF AAS

17. Flame AAS

18. F L A ME
T E M PERATURE
F O R VA R IOUS
G A S M IXT U RE

20. Flame AAS
• short analysis time
• good precision
• Easy to use
• cheap
Advantages
• Sensitivity
• Dynamic Range
• requires flammable gas
• Unattended operation not possible because of flammable gas
• must not contain excessive amount of dissolved solids
Limitation

21. GRAPHITE
FURNACE AAS

22. Graphite Furnace AAS
Advantages
• Small sample sizes
• Very little or no sample preparation
• High sensitivity due to
• Entire sample is atomized at one time
• Free atoms remain in optical path longer
• Reduced sample volume
• Ultra trace analysis possible
Limitation
• very slow
• fewer eleme nts can be analysed
• poorer precision
• more chemical interferences
• method development requires skill
• standard additions calibrations required more frequently
• expensive consumables

23. Spectral
Absorbance by molecular
species
Scattering by non volatile
salt particles ,oxides ..etc
Absorbance by closely
absorbing atoms
Non
spectral
Specific
Solute volatilization interference eg :
Po4 forms complexes with ca
Dissociation interference
Eg: Oxides & hydroxides etc
Ionization interference
Non specific
Viscosity
Surface tension
Density of analyte
INTERFERENCES

24. Microwave Digestion Sysytem
• MDS is technique for converting solid
samples into solutions suitable for analysis
by AAS
• Solid sample is chemically digested using
liquid reagent by microwave heating in a
closed container
• Closed container generates temp upto 260
degree Celsius which accelerates
digestion process

25. LEADCARE® II BLOOD LEAD
ANALYZER

26. About the LeadCare II
Blood Lead Analyzer
It is a portable device for testing
the amount of lead in capillary
whole blood.

27. How the LeadCare II System Works
The LeadCare II System uses an electrochemical
technique called Anodic Stripping Voltammetry (ASV)
to determine the amount of lead in a blood sample

28. Blood is mixed with LeadCare Treatment
Reagent and the red blood cells (RBC)
are lysed, which releases the lead that is
bound to the RBC wall.
A negative potential is applied to the sensor
to accumulate lead atoms on the test
electrode. The potential is rapidly reversed
releasing the lead ions.
The current produced is directly proportional
to the amount of lead in the sample. The area
underneath the curve is used to calculate a
quantitative blood lead result.
1
3
2 Reduction step Oxidation (stripping) step

29. The testing procedure consists of the following steps:
1. Verify you have the required materials.
2. Perform quality control testing on both levels of quality control and
verify the results are within the acceptable ranges.
3. Collect capillary blood sample. Check the capillary tube for correct
filling.
4. Add blood to the treatment reagent tube.
5. Insert a sensor and match the sensor lot number with the display.
6. Using a dropper, obtain sample from the treatment reagent tube,
touch the dropper tip to the X on the sensor and squeeze the walls to
dispense the sample.
7. Read and record the test result.
8. Remove used sensor.

30. STEP 1:
COLLECT BLOOD

31. STEP 2:
PREPARE
SAMPLE

32. STEP 3:
ANALYZE THE
SAMPLE

33. Interpreting Patient
Test Results
The result is in micrograms (μg) of lead per
deciliter (dL) of whole blood
No calculation is needed.
The reportable range of the LeadCare II system is
3.3 to 65 μg/dL.
“Low” in the display window indicates a blood
lead test result less than 3.3 μg/dL.
“High” in the display window indicates a blood
lead test result greater than
65 μg/dL
“High” results on LeadCare II should be
followed up immediately as an emergency
laboratory test.