Project: FT-IR
Introduction
FT-IR spectroscopy is used to deduce the bonds present in liquids, solids, and gases. It is widely used in industry, research, and teaching for qualitative analysis, but can also provide very accurate quantitative information. All molecules have a unique infrared spectrum, comparable to a person’s fingerprint. However, it is usually very difficult to interpret infrared spectra of mixtures. Chemometrics and linear algebra can circumvent this issue by picking out minute differences between spectra using statistical methods. During this lab, FT-IR will be used to match a sample of e-cigarette liquid to a reference spectrum using a metric called the hit quality index (HQI). This methods provides a measure of how well two spectra match, and a HQI of 0.99 or better is required to indicate a contaminant-free sample.
This lab will use the Perkin Elmer Spectrum One FT-IR (Fourier-transform infrared spectrometer) to determine whether e-cigarette liquids are adulterated. The Spectrum One is in NS 226. Before lab, read Rodriguez et al (2011). Focus on the paragraph regarding hit-quality index calculation.
The general order for FT-IR sampling is:
- Collect a background (no sample present)
- Collect sample spectra by placing a drop of sample on the instrument. (Repeat 3X for each sample.)
You will collect 3 replicate spectra for each sample and 3 spectra of the reference sample.
Safety
- This lab will require the use of small amounts of methanol; avoid contact with skin and eyes. (Wear goggles and gloves.)
- Although samples are over-the-counter products, you should avoid ingesting and/or contacting them with your skin.