Pharma Research Library | Pharma Info Index Research | Innovation | Opportunities |
About author :
Jony Mallik*, Sourav Das
Department of Pharmacy,
Southern University Bangladesh, Chittagong, Bangladesh
*e-mail: [email protected]
INTRODUCTION :
X-ray is a very potential EMR (Electromagnetic Radiation) having a very short wave length ranges from 10-6 ~10-8 cm. It can travel with the velocity of light and can also be reflected, refracted, polarized and absorbed. Due to its variation in character, it has numerous application in pharmaceutical field. To perform an analysis via X-ray, number of method can utilized by pharmaceutical scientists. That are, X-ray absorption, X-ray emission, X-ray diffraction. Each method has particular application area as for pharmaceutical and scientific analysis. Among the different method, X-ray diffraction is most important and meaningful for pharmaceutical analysis. Because it is the life of X-ray crystallographic technique.
Key words: X-ray, EMR, X-ray absorption, X-ray diffraction, X-ray emission, X-ray crystallographic technique
APPLICATION OF X-RAY :
1. X-ray diffraction is suitable for the analysis of crystal materials.
2. X-ray emission is used for the analysis of solid, liquid and gaseous states of materials.
3. All x-ray methods are available to use in analyzing any elements except element with very low atomic number.
4. X-ray emission may also used for determination of minute concentration of analyte in a particular sample.
5. X-ray absorption is essential for high concentration of analyte that presents in a sample.
ANALYTICAL PRINCIPLE :
X-ray diffraction is a method of whole x-ray analysis in which the monochromatic ray (K radiation with known wave length) is placed on a plane of crystal lattice and subsequent reflection occur in proper directions. Diffraction phenomena is depends on
1. Plane of crystal lattice
2. Wavelength of the radiation applied.
3. Angle of incident and reflected ray (Diffraction angle/θ)
4. Inter-planner distance (d)
X-ray diffraction procedure is the fundamentals of X-ray crystallography. Because diffraction is only applicable on to the crystals . X-ray crystallography is the study of crystal structure by means of x-ray diffraction. During the diffraction the ray show some manners where most presentable is the maintenance of a fixed distance by two parallel ray and they obey “Bragg’s Equation”
Bragg’s Law refers to the simple equation:
nλ = 2d sin θ
derived by the English physicists Sir W.H. Bragg and his son Sir W.L. Bragg in 1913 to explain why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (θ, λ). The variable d is the distance between atomic layers in a crystal, and the variable lambda is the wavelength of the incident X-ray beam; n is an integer. This observation is an example of X-ray wave interference , commonly known as X-ray diffraction (XRD), and was direct evidence for the periodic atomic structure of crystals postulated for several centuries. The Braggs were awarded the Nobel Prize in physics in 1915 for their work in determining crystal structures beginning with NaCl, ZnS and diamond. Although Bragg’s law was used to explain the interference pattern of X-rays scattered by crystals, diffraction has been developed to study the structure of all states of matter with any beam, e.g., ions, electrons, neutrons, and protons, with a wavelength similar to the distance between the atomic or molecular structures of interest.
For proper diffraction measurement two important technique may employed
1. X-ray diffraction camera/ camera technique (powder diffraction)
2. X-ray diffractometer
Both of the technique use different mathematical way for determination of crystal nature or structure.
APPLICATION OF X-ray CRYSTALLOGRAPHY IN PHARMACEUTICAL SCIENCE
The tools of X-ray Crystallography use for following pharmaceutical purposes:
1. Identification of the compound structure.
2. Determination of particle size (crystal lattice)
3. Determination of diffraction angle by goniometric analysis
4. For characterization of pharmaceuticals by XRPD (X-ray powder diffraction) in solid form
5. Determination of temperature & humidity tolerance of crystal powder by XRPD.
6. For analyzing the crystal structure by XRPD.
CONCLUSION :
Modern pharmaceutical analysis mostly relies on XRPD (X-ray powder diffraction) or X-ray crystallography. Hence the instruments regards to XRPD camera or diffractometer improves day by day and utilizes in different sector of pharmaceutical field. It’s actually a reliable tools for analysis of crystal structure and their attributes to pharmaceutical goods manufacturing. Special care and precaution need to start the routine analysis by using X-ray diffraction technique for crystallographic determination of structure of lattice or plane of lattice.
