introduction instrumentation different x ray methods example

1. ANALYSIS OF PHARMACEUTICALS BY
X - RAY CRYSTALLOGRAPHY.
PRESENTEDBY
MANIKANDANT
M.PHARMI SEMESTER
DEPT. OF PHARM. ANALYSIS
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2. INTRODUCTION:
 Method to determine the arrangement of atoms within a
crystal.
 A beam of x ray strikes a crystal and causes the beam of light to
spread into many specific directions.
 X-ray beam hit the crystallized molecule & diffract as the X-
rays.
 This forms a pattern --X-ray diffraction pattern.
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3.  From the angle and intensities , three-dimensional picture can
be obtained from the density of electrons within the crystal.
 It is a tool to identify the atomic and molecular structure of a
crystal.
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4. Instrumentation
 Three main fields of x-ray spectroscopy are
X-ray absorption
Diffraction
Fluorescence
 Optical system varies in each case.
 Component parts of the equipment are same.
 The main components are
1. Production of X-rays
2. Collimator
3. Monochromator
4. Detectors
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5. 1.Production of x-rays
X-rays are produced inside the x-ray tube by the interaction of
high energy electrons with the atoms of the anode.
Conditions necessary:
 Source of electrons
Target (anode)
High potential difference
Cooling facility
Coolidge X-ray Tube
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6.  Cathode is a filament of tungsten metal heated by a battery
to emit the electrons.
This beam of electrons moves towards anode and attain the
kinetic energy
 99% of energy is converted into heat by collision
 Remaining 0.5- 1% is converted to X-rays by strong
coulomb interactions ( Bremsstrahlung process).
Generally the target gets very hot in use.
 This problem has been solved by cooling the tube with
water.
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7. 2.Collimator.
The X-rays produced by the target material forms a hemisphere at
the centre.
To get a narrow beam of X-rays, the X-rays generated are allowed
to pass through a collimator.
The collimator absorbs all the
X-Ray except the narrow beam
that Passes between the gaps.
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8. 3.Monochromator
They are two types;
A. Filter monochromator:
 A filter absorbs undesirable radiation but allows the radiation of
required wavelength to pass.
 Example: zirconium filter --used for molybdenum radiation
 When X-rays emitted from molybdenum are passed through a
Zirconium filter.
 Zr strongly absorbs the radiation of molybdenum at short
wavelengths.
 It weakly absorbs the K alpha lines of molybdenum and allows the K
beta lines to pass.
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9. B.CRYSTAL MONOCHROMATOR.
 A crystal monochromator is made up of a suitable crystalline
material (sodium chloride, lithium fluoride, quartz).
The beam is split up by the crystalline material into the
component wavelengths --same way as a prism splits up the
white light into rainbow
 Such a crystalline substance is called an analysing crystal.
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10. Crystal monochromator are of two types
Flat crystal
Curved crystal
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11. 4.Detector
X-ray intensities can be measured and recorded
by
A. Photographic methods
B. Counter methods
1) Geiger muller counter
2)Proportional counter
3) Scintillation counter
4) solid state semi conductor
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12. A. Photographic methods:
A plane or cylindrical film is used to record the position and
intensity of X-ray beam.
The blackening of the developed film is expressed in terms
of density- units D given by
D = log I˳/I
Where, I˳ and I refer to the incident and transmittance
intensities of X-rays respectively.
The value of D is measured by densitometer.
This is used in diffraction studies
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13. B. Counter methods
1) Geiger Muller Counter
 The Geiger tube is filled with an inert gas (argon)
 Central wire anode is maintained at a positive potential (800 to 2500V).
 When an X-ray is entering the Geiger tube,
 This ray undergoes collision with the filling gas, resulting in the
production of an ion pair.
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14.  The electron produced moves towards the central anode.
 Positive ions moves towards outer electrode.
 The electron is accelerated by the potential gradient (causes
the ionisation of large no. of argon atoms)
 Resulting production of electrons --travel towards the
central anode
 This results in an output pulse of 1 to 10v.
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15. Advantages : -
The Geiger tube is inexpensive and is a trouble-free
detector.
Disadvantages : -
Geiger tube-- falls rapidly at wavelength below 1 Aº.
A Geiger tube cannot be used to measure the energy of
ionising radiation.
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16.  B) Proportional counter:
Its construction is similar to a Geiger tube counter.
A proportional counter is filled with a heavier gas (xenon or krypton).
The heavier gas is preferred because it is easily ionised.
It is operated at the voltage below the Geiger plateau.
 C)Scintillation detector:
The scintillation detector ---useful for measuring x-rays of short
wavelengths
When X- ray is incident upon the crystal, the emitted pulses of visible
light are detected by the photomultiplier tube.
Crystal used sodium iodide( activated by thallium) , anthracene,
naphthalene.
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17. DIFFERENT X- RAY METHODS
X ray absorption method
X ray diffraction method
X ray fluorescence method
Auger emission spectroscopy
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18. X -ray Absorption method
 A beam of x-ray is allowed to pass through the sample.
 Wavelength at which a sudden change in absorption occurs is used
to identify an element (sample).
 Magnitude of the change determines the amount of particular
element present.
 Used in elemental analysis of barium and iodine in body.
 It is helpful in certain cases like elemental analysis and thickness
measurement.
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19. X-ray Fluorescence methods.
 X-ray is generated within the sample and by measuring the
wavelength and intensity of the generated x rays.
 One can perform qualitative and quantitative analysis.
 The primary X-ray ejects electron from inner energy levels where
the wavelength is equal to absorption edge.
 But when the wavelength is shorter than absorption edge it emits
secondary X-ray when electrons fall into inner vacant levels.
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20. Auger Emission spectroscopy.
AES measure electrons emitted from the surface,
induced by electron bombardment.
The primary X-rays eject electrons from inner
energy levels.
Once the atom is ionized, it must relax by either
emitting a photon or an electron
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21. X-ray Diffraction Method.
 It is based on constructive interference of monochromatic x
ray and a crystalline sample.
 x-rays are generated by a cathode ray tube, filtered to produce
monochromatic radiation and directed towards the sample.
 The interaction of incident rays with the sample produces
constructive interference (condition satisfy Braggs laws).
 These methods are based on the scattering of x rays by
crystal.
 By this ,the crystal structure of various solid compounds can
be identified.
 These methods are extremely important as compared with x-
ray absorption and x-ray fluorescence methods.
 nλ= 2dsinθ
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22. X-RAY DIFFRACTION METHODS.
1)Laue photographic method.
2)Bragg x-ray spectrometer method
3)Rotating crystal method
4)Powder crystal method.
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23. 1)Laue photographic method.
There are two methods
Transmission method
Back reflection method
 TRANSMISSION METHOD
 A - source of X-rays.
 B - pinhole collimator.
 C - crystal to investigate structure
 D – film on a rigid base
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24.  This film is provided with beam stop to prevent direct beam
from causing excessive fogging of the film.
 The x-rays are recorded on photographic plate is used to study
the diffraction patterns which gives the structure of crystal.
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25. Back-Reflection Method
 It is similar to Transmission method
The film is placed between the x-ray source and
the crystal.
The beams which are diffracted in a backward
direction are recorded.
Method for the study of
large and thick Specimens.
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26. Braggs X-ray Spectrometer Method.
 A beam of x-ray is passed through a crystals
 The emitted x-ray are obtained on a photo graphic plate in a form of
pattern (laues photograph)
 Using photographs, Braggs analysed the structure of crystals of NaCl,
KCl and ZnS.
 Braggs devised a spectrometer -- measure the intensity of x-ray beam.
 When x-rays are scattered from a crystal lattice, peaks of scattered
intensity are observed to the following conditions:
 1. The angle of incidence = angle of scattering.
 2. The path length difference is equal to an integer number of
wavelengths.
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27.  The Braggs equation
nλ= 2dsinθ
 where n is a positive integer
 λ is the wavelength of incident wave
 d is the path length
 θ is the incident angle
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28. Rotating Crystal Method
X rays are generated in the x-ray tube --the beam
is made monochromatic by a filter.
From the filter, the beam is passed through
collimating system which permits a fine pencil of
parallel x-ray
From the collimator, the x-ray beam is made to
fall on a crystal mounted on the shaft which can
be rotated at a uniform angular rate by the small
motor.
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29. Now the shaft is moved to put the crystal into slow rotation
This causes the sets of planes into their reflecting
positions.
Each plane will produce a spot on photographic plate.
Photographs can be taken in two ways:
Complete rotation method
Oscillation method
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30. Powder Crystal Method
 In this method, sample can be taken as little as 1mg of the material.
 X-ray powder diffraction (XRD) is a rapid analytical technique
primarily used for phase identification of a crystalline material.
 The analysed material is finely ground and homogenized.
 A- source of X-rays.
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31.  X-ray beam is allowed to fall on the powdered specimen P
through the slits S1 and S2.
 Fine powder, p is struck on a hair by means of gum and is
suspended vertically in the axis of a cylindrical camera. This
enables sharp lines to be obtained on the photographic film
which is surrounding the powder crystal in the form of a
circular arc.
 After falling on the powder , it passes out of the camera
through a cut in the film.
 It is observed on the photographic plate.
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32. Application
 To determine structural properties and atomic arrangement.
 Identification of fine-grained minerals --clays and mixed layer
clays that are difficult to determine optically.
 Determination of Cis- trans isomerism.
 Differentiation of sugar.
 X-ray analysis of milk powder.
 It is used for the identification of unknown crystalline materials
(e.g. minerals, inorganic compounds).
 Determination of unknown solids --studies in geology,
environmental science, material science, engineering and biology.
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33. Example
Determination of minor and trace elements in
kidney stone
1)Experimental setup for XRF studies on kidney stone.
XRF spectrometry on different kidney stones
Exposure of kidney stone
XRF measurement by the detector
Background subtraction from XRF spectrum
Spectrum analysis by PyMCA
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34. Optimisation of PyMCA parameters
Information of identified peak elements
Determination of elements and their concentration.
The elements which were identified from this techniques are
silver, arsenic, bromine, chromium, copper, gallium,
selenium, germanium , etc
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35. XRF SPECTRUM OF THE APATITE KIDNEY
STONE
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36. XRF SPECTRUM OF THE CYSTINE KIDNEY
STONE
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37. RESULT AND DISCUSSION
The results from XRF analysis can serve as a reliable
method for accurate determination of elements and
its composition in the kidney stones.
The result from such analysis can be utilised to
develop more effective methods for the new
medicines for kidney stones.
PyMCA program is used to identify elemental
composition and their concentrations of the kidney
stones with high degree of accuracy.
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38. REFERENCE
 1)Instrumental method of analysis-Willard’s, 7th edition, CBS
Publishers
page no:320-345
 2)Instrumental method of chemical analysis- Chatwal, Himalayan
Publishing House page no:2.303-2.339.
 3) Alvarez, M. and Mazo-Gray, V, “Determination of trace elements
in organic specimens by energy dispersive x-ray fluorescence using
a fundamental parameters method,” X-Ray Spectrom., doi:(2005).
 4) Hirokawa, Y., Shibata, Y., Konya, T., Koike, Y. and Nakamura, T.,
“X-ray fluorescence analysis of Co, Ni, Pd, Ag, and Au in the
scrapped printed-circuit-board ash,” X-Ray Spectrom., doi (2013).
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