Introduction to FTIR Spectroscopy and Open-Source Analysis Software

Fourier Transform Infrared Spectroscopy (FTIR) is an analytical technique used to identify chemical compounds and functional groups, by measuring how a sample absorbs infrared radiation at different wavelengths.

Molecules vibrate in characteristic ways when exposed to infrared light. Different chemical bonds absorb energy at specific frequencies, producing an infrared spectrum that acts like a molecular fingerprint.

FTIR is commonly used for purposes such as:

• Identifying unknown materials
• Confirming chemical structures
• Monitoring chemical reactions

An FTIR spectrum is usually displayed as:

• X-axis: Wavenumber (cm⁻¹)
• Y-axis: Absorbance or Transmittance

Important regions include:

To analyze an FTIR spectrum:

1. Identify major peaks
2. Determine the functional groups associated with each peak
3. Examine the fingerprint region
4. Compare with reference spectra
5. Look for appearance, disappearance, or shifts of peaks after reaction/treatment

Normalization adjusts spectra to a common scale so samples can be compared directly. Normalization helps to compensate for factors like different sample thickness, instrument variability, differences in crystal contact, and variations in sample concentration. After normalization, it will be much easier to compare peak heights and shapes between samples.

Raw FTIR spectra often have sloping or curved baselines due to instrument drift, scattering effects, or environmental interference. Baseline correction removes these artifacts so peak intensities more accurately reflect chemical composition.

There are many openly accessible softwares available for download on the internet which aid in the steps toward full analysis of a spectra, or at the least identifying components within a mixture.

We will explore 2 of these applications on this page: Open Specy and Spectragryph.

There are strengths and weaknesses to both which will be examined below.

Additionally, here are some other softwares which may be worth checking out but which are not outlined on this page:

• Quasar: An open-source collection of spectroscopic data analysis toolboxes built on Python. It extends the visual Orange machine learning suite, allowing you to build reproducible workflows for baseline subtraction, normalization, peak analysis, and multivariate analysis. Download and explore it on the Quasar Platform.
• SpectraFit: A modern, open-source Python tool specifically designed for interactive and automated peak fitting. It provides a standardized platform that standardizes baseline correction, peak assignment, and model sharing. You can find the publication and repository details on the ACS Publications SpectraFit Abstract.
• Ira FTIR Explorer: A lightweight, free, and open-source JavaScript (NWJS) application tailored for exploring and rapidly analyzing FTIR data, commonly used for pharmaceutical applications. It can be cloned and run locally via the Iraspec GitHub Repository.

1. Room #, ICFAR
2. PerkinElmer Inc.
3. 501 Rowntree Dairy Road, Woodbrid

Knowing what chemicals are in the lab and how they interact with each other is critical when accidents happen.

1. Appropriate SDS sheets should be viewed online.
2. Note the hazards listed on the door to the lab. If you introduce any new equipment or materials you must clear them with the responsible person listed on the lab door. If the responsible person is out of date, contact the departmental administrators to get it updated.

1. Room #, ICFAR
2. PerkinElmer Inc.
3. 501 Rowntree Dairy Road, Woodbrid