Ivane Javakhishvili Tbilisi State University
Faculty of Exact and Natural Sciences
Substance Research Institute
Ketevan Museridze
keti_93@yahoo.com
Determination of Metal Concentrations in
Surface Waters and Soils Using Atomic Absorption
Spectrometer
Atomic absorption spectroscopy is a common technique used in many chemical
measurements requiring a high degree of precision and accuracy, such as food & drug
safety, clinical diagnostics and environmental sampling. Atomic absorption
spectrometers may be used to analyze the concentration of over 70 different elements in
a given sample solution, making them a very valuable instrument in any laboratory.
Method
We used Atomic-Absorption spectrometer AAnalyst 800 (Producer – company
PerkinElmer Inc., USA; year of produce – 2003) for determination of the metal
concentration in water (Cu, Pb, Zn, Ni, Co, Mo, Cr, Mn, Cd, Ag) and soil (Cu, Pb,
Zn, Ni, Co) samples. Electrothermal and flame methods of atomization were used.
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A spectrometer is fully operated via computer, using the software support
WinLab32. The given program provides full automatic control of the device, allows
us to make changes in the methods, memorize and receive information of
measurements of the particular group of elements in a desirable form.
The basic components of an atomic absorption instrument:
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The light source that emits the spectrum of the element of interest;
An “Absorption cell” in which atoms of the sample are produced (flame, graphite
furnace);
A monochromator for light dispersion;
A detector that measures the light intensity;
A display that shows the reading after it has been processed by the instrument
electronics.
Light source
Sample Cell
Flame or Furnace
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Specific Light Measurement
Monochromator
Detector Electronics
Readout
The light source (hollow cathode lamp) emits a spectrum specific to the element of which it
is made, which is focused through the sample cell into the monochromator. The method of
heavy metal definition via Atomic-absorption spectrometer is based on the properties of
specific metal atoms to absorb specific wavelength of light. The electronics will measure
light attenuation and convert those readings to the actual metal concentration of the sample.
Putting lamps for various metals
The lamp holder with positions for 8 source lamps allows having 8 lamps
simultaneously that are prepared for work and can pass from one element to
another.
Process of measurements
Choose a desired method of atomization by means of the computer, with use of
software support WinLab32
1. When using the electrothermal atomization method the aliqoute part of a sample is
put in a graphite furnace of the spectometer using sampling device (autosampler)
According to the programme, heating of a sample is performed in the inert gas
(argon) stream, including drying, incineration, atomization of a sample and clean-out
of the furnaces.
2. The flame atomization method is also used. The injectoration of the analyzed
portion of the sample in the flame of a torch is performed by means of capillary. The
mix of air – acetylene is used for the formation of a flame.
Reactants and equipment are necessary for measurements
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A nitric acid of special cleanliness
Deionized water
Adjustable pipettes
Measuring Flasks
Gaseous Argon of high cleanliness
Gaseous Acetylene of high cleanliness
Atomic Spectroscopy Single-Element Pure Standards.
Adjustable pipette
Measuring Flasks
Standards
Kura (მტკვარი-Mtkvari) Starting in northeastern Turkey, it flows through
Turkey to Georgia, then to Azerbaijan, and enters the Caspian Sea. The
total length of the river is 1,515 kilometers.
Water sample preparation for measurement
Soil sampling
10
Prior to atomic absorption spectroscopy analysis, some samples (soil) must be digested
to ensure for accurate analyte measurement, which can be performed by using
BERGHOF speedwave MWS-3
The Berghof MWS-3
microwave pressure
digestion system enables
considerably shorter
sample preparation times
to be achieved (with
digestion duration
of 15-20 minutes on
average) for sophisticated
analysis and routine
laboratory
application.
Preparing soil samples
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We put sample of dried soil in a mortar;
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Crushed it with pestel and sieved (150 µm);
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Weighed approximately four grams of sample with the precision of
0.001 gram;
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Put the sample into a fission container of microwave system;
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Added to the sample hydrocloric acid of 21 mililiter;
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Then added drop by drop nitric acid of 7 mililiter;
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Fissured it according to the program;
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Filtered the obtained extract in 50 ml measuring retort, washed off
residue on the filter with deionized water;
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Measured metals in the obtained filtrate.
Quality Assurance of Measurements
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Transport Blank - Distilled water taken from the laboratory to the sampling site and returned
to the laboratory unopened; it is used to document contamination caused by the laboratory
conditions, transporting and field handling procedures.
Transfer Blank - Distilled water which is subject to all aspects of sampling and analysis
excluding the contact with all samplers and apparatus; it is used for checking the possible
contamination from the environment.
Rinsate (equipment) blank - Distilled water which is subject to all aspects of sampling and
analysis including the contact with all samplers and apparatus; it is used to determine the quality
of cleanliness of samplers and apparatus for sampling before sending them to the field site.
Check-out standards – Sample with known concentration of analyte, is used for checking that
the analytical accuracy is under control and the level of displacement caused by calibration is
satisfactory.
Analytical duplicate – two identical aliquots of sample collected at the same time, at the same
place and handled in exactly the same manner; they are used as a measure of precision
associated with sample handling, storage, preparation, and analytical procedures.
Blanks – distilled water to which all reagents are added in the same volumes that are used in the
same processing. It should be carried through the complete resulting from the analytical process.
Obtained Results
#
Metal
MDL µg/l
River Water µg/l
Soil mg/kg
Method Detection Limit
1
Cu
1.5
9.8
40.59
2
Pb
0.7
0.70
9.3
3
Zn
1.5
12.8
62.13
4
Ni
Co
Mo
Cr
Mn
Cd
Ag
0.5
0.7
0.3
0.1
0.3
0.05
0.1
1.12
0.12
3.2
2.2
12.4
0.050
0.100
43.95
3.06
5
6
7
8
9
10
Future work
The world’s largest lysimeter network
SOILCan investigates material and water fluxes in the soil as well as
soil balances. This kind of data is lacking world-wide, but is absolutely
crucial for the development and improvement of models for
the exchange processes between the biosphere, atmosphere
and hydrosphere.
References
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AAnalyst 600/800 atomic absorption spectrometers
http://www.perkinelmer.com/CMSResources/Images/44-74392BRO_AAnalyst600800.pdf
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D.Kekelidze, G.Kekelidze, K.Tsetskhladze, G.Tsotadze, O. Sulava. The Use of Atom-Absorption
Spectrometer Perkin-Elmer AAnalist800 During the Surface Water Analysis. Problems of river Monitoring
and Ecological Safety of south Caucasus. U.S. Civilian Research and Development Foundation. pp. 228233.
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T. Jakhutashvili, N.Kekelidze, E.Tulashvili. Some Aspects of Methodology of Works on Quality Assurance
of Measurements at Field and Laboratory Researches. Problems of river Monitoring and Ecological Safety
of south Caucasus. U.S. Civilian Research and Development Foundation. pp. 3003-3008.
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Atomic Absorption Spectroscopy.
http://www.aurorabiomed.com/atomic-absorption-spectroscopy.htm
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Atomic absorption spectroscopy.
http://en.wikipedia.org/wiki/Atomic_absorption_spectroscopy
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tereno-newsletter-2011-1-engl.
http://teodoor.icg.kfa-juelich.de/tereno-newsletter/newsletter/tereno-newsletter-2011-1-engl.pdf/view
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TERENO – Finding local solutions to global change.
http://www.trio-medien.de/uploads/media/TERENO-Imagebrosch%C3%BCre.pdf
Thank you for the attention!