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)