Fourier Transform Infrared Spectroscopy at Aberystwyth

As of 1^st February 2003 we will be moving to the Department of Chemistry, UMIST, Manchester. These pages will no longer be updated.

Fourier transform infrared (FT-IR) spectroscopy measures dominantly vibrations of functional groups and highly polar bonds. Thus these (bio)chemical 'fingerprints' are made up of the vibrational features of all the samples components [1]. For microbial samples these will include DNA/RNA, proteins, membrane and cell-wall components.

FT-IR spectrometers record the interaction of IR radiation with experimental samples, measuring the frequencies at which the sample absorbs the radiation and the intensities of the absorptions. Determining these frequencies allows identification of the sample's chemical makeup, since chemical functional groups are known to absorb light at specific frequencies.

FT-IR experiments generally can be classified into the following two categories:

• Qualitative analysis - where the aim is to identify the sample.
   

• Quantitative analysis - where the intensity of an absorption (or more commonly absorptions) is related to the concentration of the component. And these may be displayed as topological image maps.

Within Microbiology, FT-IR has been shown to allow the chemically-based discrimination of intact microbial cells, without their destruction, and produces complex biochemical fingerprints which are reproducible and distinct for different bacteria. In particular Naumann and co-workers [2-3] have shown that FT-IR absorbance spectroscopy (in the mid-IR range, usually defined as 4000-400 cm^-1) provides a powerful tool with sufficient resolving power to distinguish microbes at the strain level.

References:

1. Griffiths, P.R. and de Haseth, J.A. (1986) Fourier transform infrared spectrometry. John Wiley, New York.
    

2. Helm, D., Labischinski, H., Schallehn, G. and Naumann, D. (1991) Classification and identification of bacteria by Fourier transform infrared spectroscopy. J. Gen. Microbiol. 137, 69-79.
   

3. Naumann, D., Helm, D. and Labischinski, H. (1991) Microbiological characterizations by FT-IR spectroscopy. Nature 351, 81-82.
   
4. Naumann, D., Helm, D., Labischinski, H. and Giesbrecht, P. (1991) The characterization of microorganisms by Fourier-transform infrared spectroscopy (FT-IR). In: Modern techniques for rapid microbiological analysis, pp. 43-96 (Nelson, W.H., Ed.) VCH Publishers, New York.

FOR MORE READING.....

A BIT ABOUT SPECTROCOPY:

This is the interaction of electromagnetic radiation with matter can cause redirection of the radiation
and/or transitions between the energy levels of the atoms or molecules. The following can happen:

• The light may be scattered
   

• Light may be emitted
  

• Or in the case of FTIR infrared radiation may be absorbed
  
• This page shows you a picture of the electromagnetic spectrum

METHODOLOGY

• We mainly use Diffuse Reflectance Absorbance

APPLICATIONS: (More coming soon)

• Goodacre, R. Timmins, É.M., Rooney, P.J., Rowland, J.J. & Kell, D.B. (1996) Rapid identification of Streptococcus and Enterococcus species using diffuse reflectance-absorbance Fourier transform infrared spectroscopy and artificial neural networks. FEMS Microbiology Letters 140, 233-239. FULL PAPER (23.6k)
   

• Winson, M.K., Goodacre, R., Woodward, A.M., Timmins, É.M., Jones, A., Alsberg, B.K., Rowland, J.J. & Kell, D.B. (1997) Diffuse reflectance absorbance spectroscopy taking in chemometrics (DRASTIC). A hyperspectral FT-IR-based approach to rapid screening for metabolite overproduction. Analytica Chimica Acta 348 , 273-282. ABSTRACT (2.5k)

Other sites dealing with Fourier transform infrared spectroscopy (link will appear soon) may be found here.

In the following pages, pressing the button will bring you back to this page.

The pyrolysis mass spectrometry home page.

The chemometrics home page.

The Aberystwyth quantitative biology group home page.