Resource for schools & colleges - learn how to perform FTIR analysis and test your spectrum interpretation skills
Modern FTIR spectrometers are capable of analysing liquid and solid samples, with no sample preparation required. For neat liquids, the sample is simply placed on the diamond window. For solids, the sample is placed on the diamond & an adjustable clamp (shown in video, but not in use) lowered to apply pressure to ensure good contact - this method works fine but is very difficult to automate. For this experiment, solid samples are dissolved in solvent, to automate sample loading, and dried to leave a thin film of solid for FTIR analysis.
Open and download the pdf file to view the chemical structures of six different compounds A to F (mix of neat liquids and solutions). Using the IR band table (supplied by tutor) predict the major IR peaks you would expect to observe for each compound. When ready, click on the tutor link to open the automated FTIR system (PC only password supplied by tutor). Select each sample, one by one, in series or at random and generate an FTIR spectrum for each compound. Or click on the student link to analyse FTIR spectra only. Compare your predicted IR band values to the major peaks observed in the spectra and match the sample tube number to the correct compound letter
Step 1: Select the sample tube number you want to analyse & click START
Step 2a: If the sample is a neat liquid, the sample is loaded & the nitrogen flow is zero
Step 2b: If the sample is a solution, nitrogen flow is turned on & the solvent evaporated to leave a thin solid film
Notes: users do not know which samples are neat lquids or solutions but the software knows ! and nitrogen flow control is automated
Step 3: FTIR takes 10 scans over 10 seconds to generate a spectrum. The spectra is shown on screen & can be downloaded and saved as a pdf when all 6 spectra have been correctly identified
Step 4: The FTIR spectrometer is flushed clean & dried and a background scan taken ready for the next sample
