How to Interpret FTIR Data
FTIR stands for Fourier transform infrared spectroscopy. An infrared spectrum is obtained based on the photoconductivity, emission, absorption or scattering of the compound being measured. This uses algorithms that convert the raw data into the spectrum. The goal of the measurement is to determine how much light is absorbed by the compound at different wavelengths. This type of spectroscopy is used for chemical and enzymatic reactions, to determine unknown compounds and to take quantitative measurements.
Other People Are Reading
Instructions
-
-
1
Compare the obtained spectrum for an unknown compound to existing spectra found in a database. The search matches your unknown compounds spectra with spectra collected for known compounds. Several matches with different percentage of similarity will result. The match with the highest percentage is most likely the compound. Spectral databases normally come with the machine's software, but they can also be found online.
-
2
Compare the absorbance of a sample of unknown concentration to a calibration curve composed of the same substance at different concentrations. The calibration curve will plot the absorbance for each of the different concentrations. Use statistical software to determine the regression line for the plotted points. Then substitute the absorbance of the unknown concentration sample and calculate the concentration. Factor in dilution to the final concentration calculation.
-
-
3
Determine the chemical structure based on known information for chemical bonds and atom light absorption information. Each line in the spectra correlates to a compound and chemical bond. With a list of the different bonds it is possible to determine the chemical structure of the compound. This is only done when the compound of interest does not have any matches with a spectra database.
-
4
Look for key spectral bands that correlate to known bonds. This is a faster way of interpreting data then analyzing every band in the spectrum. Think about how the sample was prepared and use the information from the key bands to build up a picture of the compound of interest. This is the easier method of interpretation because even known compounds will contain bands that are not classified.
-
1
References
- Photo Credit Jupiterimages/Photos.com/Getty Images
