Neutron Activation Analysis for
Life Sciences
Supervised by: Prof. M.V Frontasyeva and Dr. W. Badawy
Frank Laboratory of Neutron Physics
The Sector of Neutron Activation Analysis and Applied Research
Summer practice in JINR Dubna 06-23.09.2016
Participants
Josiel de Jesús Barrios Cossio, Cuba
Dimitrijević Aleksandra, Serbia
Dmitrović Svetlana, Serbia
Zdolsek Nikola, Serbia
Alexander Naa’ilah, South Africa
Biyela Talente, South Africa
Yende Nomcebo Fikile, South Africa
Mdunjana Ntandokazi, South Africa
Kobese Nokubonga, South Africa
Neutron Activation Analysis (NAA)
• NAA is a method for determination of elements based on
conversion stable nuclei to other, mostly radioactive nuclei
via nuclear reactions and measurements of reaction
products [Bode, 1996]
• NAA was discovered in 1936 by G. Hevesy (Hungary) and H.
Levi (Denmark)
Fundamentals of NAA
Absolute Standardization
Relative Standardization
m=
Absolute method
- Requires precise knowledge of (E)
- Accurate measurement of (E) and 
Anc
Anc,s
te,s
-
e
ms
e- te
- It requires standards to have all the
elements
- The error mainly depends on ms and
Anc
Applications
Advantages
Limitations
• Wide possibilities of applications
• Need for nuclear reactor
• Non destructive analysis
• Work with radioactive materials
• Multi-element analysis
• Time of analysis
• Sensitivity to parts-per-billion
for specific elements
• Sample preference
• Customizable analysis
Comparison between NAA and other techniques
• Atomic Absorption Spectrometry (AAS)
The study of absorption spectra by means of passing electromagnetic
radiation through an atomic medium that is selectively absorbing; this
produces pure electronic transitions free from vibrational and rotational
transitions
• X-Ray Fluorescence Analysis (XFA)
X-ray Fluorescence (XRF) analysis is a widely used method of elemental
analysis providing both qualitative and quantitative compositional
information.This analysis is widely used for elemental analysis and chemical
analysis, particularly in the investigation of metals, glass, ceramics and
building materials, and for research in geochemistry, forensic science and
archaeology.
• Synchrotron radiation
Synchrotron radiation is the name given to the radiation which occurs
when charged particles are accelerated in a curved path or orbit.
Classically, any charged particle which moves in a curved path or is
accelerated in a straight-line path will emit electromagnetic radiation.
The disadvantages of using this methods above is that they are expensive,
difficult to calibrate and other factors like sample characteristic,
availability and accuracy and precise.
While INAA is relatively low on the prices when we compare it to these
techniques
IBR – 2 Reactor in JINR
Parameters of IBR – 2:
- Average power 2 MW
- PuO2 fuel
-Rotation rate, rev/min:
main reflector 600
auxiliary reflector 300
16
-2 -1
- Neutron density flux 10 n·m ·s
Neutron energy distribution:
- Thermal 0.025 eV-0.5 eV
- Epithermal 0.5 eV – 100 keV
- Fast 0.1 MeV – 25 Me
Radioanalytical complex REGATA
Ch1-Ch4 –irradiation channels, S- intermediate
storage, DCV- directional control valves, L- loading
unit, RCB- radiochemical glove-cell, U- unloading
unit, SU- separate unit, SM- storage magazine, Rrepacking unit, D- detector, CB- control board, R1R3- the rooms where the system is located.
Types of NAA
• Destructive
(radiochemical) – the resulting
radioactive sample is chemically
decomposed and the elements are
chemically separated.
Non-destructive
(instrumental) – sample is kept intact and
the radionuclides are determined, taking
advantage of the differences in decay rates
via measurements at different decay
intervals
Instrumental neutron activation analysis
Instrumental neutron activation analysis (INAA) is used to determine
the concentration of trace and major elements in a variety of matrices.
A sample is subjected to a neutron flux and radioactive nuclides are
produced. As these radioactive nuclides decay, they emit gamma rays
whose energies are characteristic for each nuclide.
Measurement of content of samples
Sample preparation
.
Decay
time
.
Neutron irradiation
of samples
Decay of radioactivity
Count
time
Decay periods
Measurement of γ-ray spectra of samples and
standards with HPGe-detector
Processing of the γ-ray spectra using GENIE 2000
Calculation of element content
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Sample preparation
Irradiation of Samples
• The principle involved in NAA, is the irradiation of a sample with a neutron
source that produces specific radionuclides.
• Different sources of neutrons can be used:
•
•
•
•
Reactor (IBR-2)
Fusors
Isotope Sources
Gas Discharge Tubes
• This results in characteristic gamma rays emitted by the decaying
radionuclides. The gamma rays are quantitatively measured using gamma
spectroscopy.
• Data analysis yields concentrations of major, minor, trace and rare earth
elements.
Case Study (Joint project between JINR & SA)
• A joint study between University of the Western Cape (RSA) and Frank
Laboratory for Neutron Physics (JINR).
• Dr Paul Eze, Dr Marina Frontasyeva and Prof. Leslie Petrik
• Elemental Composition of Fly Ash: A comparitive study using nuclear
and related analytical techniques.
Processing of Gamma-Ray Spectra
 A minimum requirements
- Determine the position of peaks in the spectrum
- Estimate the areas of the peaks (together with uncertainties)
- Calculate the energy of the gamma-ray each peak represents
- Correct for counting losses due to dead time and random summing
-Make corrections for decay from a reference time
- Convert peak areas to activity or concentration, either by reference to an
efficiency function or by direct comparison with a reference spectrum
 In general,
a full computer spectrum analysis will consist of three
phases:
(1) set up data libraries for energy, peak width and efficiency
calibration and for sample analysis
(2) use spectra of reference sources to generate energy, width and
efficiency calibration data files
(3) analyse sample spectra by referring to those data libraries and
calibration files
 Software systems:
Genie 2000™ (Canberra) and GammaVision™
(ORTEC)
-Allow complete calibration of energy, peak width and detector efficiency
-Able to search through a spectrum seeking out statistically significant
peaks, assigning them to nuclides, and calculating sample activity
 GENIE 2000
- the program allows minimizing human involvement in routine long-term
measurements of the spectra of the induced activity
- simultaneous measurements are conducted
 for
visualization of information, the program automatically provides the
file with areas of interest and displays them in the window of Genie-2000
-areas of interest are graphical peak intervals found by the program while
spectra are being processed
results are stored in a file with the values of the activities of identified
isotopes and the minimal detectable activity of these isotopes
calculation of elemental concentrations in the samples is performed by a
relative method using the Concentration program
- the values of the calculated concentrations of elements with uncertainties
of calculations and minimal detectable concentrations for the given
experimental conditions are stored in the NAA database
CASE STUDY
STUDY OF SPIDER SILK COMPOSITION BY NEUTRON ACTIVATION ANALYSIS
Native Spider Silk
• Remarkable mechanical properties
• Biocompatible
• Biodegradable
• Production of native ss on industrial
level failed due to cannibalistic
nature of spiders
• Recombinant DNA technology for
production of SS proteins
Composition of spider silk
Core-shell structured fiber:
1) 2 main proteins-spindroins (Gly, Ala, Pro)
• Ala domains form β-sheat secondary structure
• Gly-Gly-Ala and Gly-Pro-Gly-X-X domains form 31 helices
2) ‘skin’
3) Glycoprotein coat
4) Lipid layer
The first NAA of spider silk
• Spider silk from Pholcus phalangoides spider
• Basement of one of the buildings in Vinča
Institute of Nuclear Sciences
• Spider silk as a potential biomonitoring
material
Preliminary results
Element
mg/kg
%
Element
mg/kg
%
Na
7110
3
Mo
58.8
31
Mg
9060
3
Ag
6.17
18
Al (P)
20100
2
Cd
1.43
10
Si
62600
34
Sb
40.5
4
S
6000
34
I
376
14
Cl
7720
7
Ba
741
5
K
10200
10
Cs
3.2
3
Ca
5.0
5
La
24
4
Sc
7.0
3
Ce
144
4
Ti
1680
11
Nd
29.6
24
V
93.2
6
Sm
5.62
31
Cr
966
4
Eu
2.94
30
Mn
559
5
Gd
2.75
9
Fe
38200
5
Tb
0.584
4
Ni
366
8
Dy
3.7
30
Co
194
6
Tm
0.022
30
Cu
507
30
Yb
4.64
31
Zn
15800
7
Lu
1.4
68
Se
10.9
8
Hf
23.7
8
As
55.8
5
Ta
5.41
2
Br
59.7
2
W
260
30
Rb
23.1
17
Au
0.23
30
Sr
148
9
Hg
3.23
16
Zr
850
30
Th
4.91
2
Nb
58.2
34
U
8.77
3
Perspectives
• Comparison of spider silk with the dust collected from the same place
• More detailed analysis of composition of spider silk
• Comparison in composition of fibers between the species
• Influence of diet on composition of fibers
• Using NAA to study the aforementioned research points as an analytical
technique.
Conclusion
• Neutron Activation Analysis (NAA) is a useful method for
the simultaneous determination of major, minor and trace
elements of geological, environmental and biological
samples in ppb-ppm range with or without chemical
separation
Acknowledgments
• Prof. Marina V. Frontasyeva
• Dr. Wael Badawy
• S.S. Pavlov
• Prof Octavian Duliu
• Nikita Sergeevich
Thank you for your paying attention
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