Rob Harvey
Lab 5: IR, Raman, IR Microscopy
Introduction:
FTIR stands for Fourier Transformed Infrared Spectroscopy. It looks at bond types in
analytes, and based on the wavenumbers that are displayed, you can determine what functional
groups are in the analyte. It is most commonly used for qualitative use, but recently quantitative
studies have been done. This lab is a quantitative study. The Raman is similar to the FTIR, but it
deals with Raman shift. Also the Raman can give readings with water as the solvent, while if you
put water in the IR, you are going to have a bad time. For this lab we are just using the Raman to
get spectra on several samples. IR microscopy is another technique, and allows you to focus on a
specific spot on the sample, like fibers. IR microscopy is very important in forensic
investigations.
Purpose:
The purpose of this lab is to learn how to use the IR by running three organic solvents,
and to learn the operation of the IR microscope by comparing carpet fibers, and to learn the
Raman by running several samples.
Procedure:
Day 1:
1. Investigate operation of IR by running 3 organic solvents
2. ID unique components of each spectrum and run a mix of the solvents
Day 2:
1. Create calibration curve by running the 3 organic solvents and nothing
absorbance and unique wavelengths
2. Run unknown mix, and find concentration.
IR Microscope
Day 1:
1. Learn how to operate scope
2. Obtain good spectrum of knowns
3. Collect fibers
Day 2:
1. Collect unknown fibers and see if these match knowns
Note: For the IR calibration curve we ran a mix of 2-butanone and water. We picked a peak at
around 1700 cm-1 which is the peak from the ketone in 2-butanone. This peak was not affected
by the water. The IR microscope was broken, so we never used it, and we ran Toluene,
Acetaminophen, and Methyl Salicylate through the Raman.
Results:
Table 1. Calibration Curve of 2-Butanone and water
Area of C=O Peak (~1700 cm-1)
6269.406
5927.958
5407.118
5065.444
3825.888
8672
Percent 2-Butanone
100%
80%
70%
60%
50%
Unknown
Calibration Curve of
2-Butanone
y = 45.40x + 2030
R2 = .8538
7000
Area
6000
5000
4000
3000
0
50
100
% Butanone
Using the equation, the % Butanone is 146%
150
Discussion:
The lab went well, using the instrument wise. We were able to get a lot of good
qualitative data, but we struggled to get good quantitative data. Our graph did not turn out as bad
as I had originally thought, but the unknown calculation was definitely off. The unknown was
made by one of the lab assistants at random, so its exact concentration is unknown as it is. The
fact that we got a percentage over 100% also shows how we had issues with the quantitative part
of the lab. Although the data did not come out very clean, we had no issues with using the actual
FTIR. The Raman went very well, and once we found the proper things to run, we had great
spectra (our toluene spectra had almost no noise whatsoever). Overall I feel that even though our
data came out weird, we were able to get a good understanding on how to use the instruments.