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Honour Seminar Presentation
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Analysis of Synthetic Compounds on Hair by Using FTIR for
Forensics Purpose Honour Seminar Presentation (SCS 4901)
Islamic Science University of Malaysia (USIM)
Hair in Forensic
Role of hair in investigation
- Trace elements
- Secondary transfer
Role of FTIR in investigation
- Can provide rapid and specific chemical composition
- Small quantity of sample needed (suitable for limited quantity of trace elements)
Introduction
Introduction
The white color on hair commonly gives an old appearance to people and they tend to do hair treatment in order to look fresh and versatile. Moreover, not only women, but also men change their hair color to look attractive and get new image in represent self-confidence and social success.
There are abundance of chemical compounds used in the hair treatment that will affect the molecular structure of the hair fiber. It can be detected by using Fourier Transform Infrared Spectroscopy (FTIR).
Hair Morphological Composition
- Outermost layer of hair fiber
- Important in chemical resistance, protection and stability of hair
- Shows the age of hair
- The larger portion of hair by mass and volume
- Important in mechanical aspect and properties of hair fiber
- Contain melanin
- Inner part with diameter 5-10µm
- Important in thermal insulation and resistance to alkali
- Contains pigment granules (pheomelanins and eumelanins)
The Cuticle
The Cortex
The Medulla
Hair Chemical Composition
Elements• C, H, O, N and S are main
elements• Sweet deposits, environment
and metabolic irregularities are primary root of trace elements
Pigments• Determine the color• Eumelanin give light color• Pheomelanin give dark color
Lipids• Free lipids• Important for the condition
known as oily hair
Proteins• Main composition in hair• Depend on the individuals diet• 20 amino acid presents in
protein
Treated and Untreated HairThere are five types of chemical treatments
Dye Bleaching Waxing StraighteningOxidation
with Chlorine
Dye – permanents, semi-permanents and temporary
(oxidative species containing phenylenediamines, aminophenols, dihydroxybenzenes, and nitro compound)
Bleaching – alkaline medium, hydrogen peroxide and ammonium
Waxing – total reconstruction with ammonia and ammonium hydroxide
Hair straightening – strong base such as such as sodium hydroxide
Oxidation with chlorine - There are 2 oxidising species whether Cl2 and HOCl that will cleave peptide bond and disulphide bond depending in the pH of water
Cont.
The Principle of Methodology
1• Obtain hair sample from the donor• Cut into certain length
2• Flattened with roller knife• Transferred to bottom KBr salt plate
3• Second KBr plate placed on the top• Run with FTIR and collect the reading of spectrum
Fourier Transform Infrared Spectroscopy (FTIR)
Improved infrared spectra
Has movable and stationary mirror.
- High resolution- High scan rate
- Respond only to modulated light
Conclusion
Infrared spectroscopy is an important technique for aiding forensic scientists in their investigations. Individual hair fibers can easily
be analyzed, and differences due to chemical damage, natural weathering, and cosmetic treatments are readily apparent.
It is also provide an information about functional group that help the researcher or investigator to predict the chemical compound.
The End
Thank You
Honour seminar Presentation
(7/12/2012)