Home Analytical Chem Preparing a sample for infrared spectroscopy
Steps
  1. 1 Grind compound to fine powder 00:07
  2. 2 Mix nujol with ground compound 00:25
  3. 3 Transfer paste to potassium bromide discs 00:43
  4. 4 Secure sample in plate holder 02:10
  5. 5 Prepare solution sample in vial 02:37
  6. 6 Transfer solution to solution cell 03:33
  7. 7 Insert sample holder into spectrometer 04:07
Analytical Chem YouTube (Curated Tutorials)

Preparing a sample for infrared spectroscopy

Protocol
Difficulty
intermediate

Steps

1
Grind compound to fine powder

A small amount of the compound is ground to a very fine powder using a mortar and pestle.

▶ 00:07
2
Mix nujol with ground compound

A few drops of nujol are added to the powder and mixed together to create a paste.

▶ 00:25
3
Transfer paste to potassium bromide discs

The nujol paste is transferred to potassium bromide discs using the flexible end of a small spatula, taking care not to scratch the disc surface. The two discs are then pressed together to create a film.

▶ 00:43
4
Secure sample in plate holder

The pressed discs are placed into a plate holder, which uses screws or springs to hold the sample tightly in place. The screws are tightened evenly to apply pressure across the plates.

▶ 02:10
5
Prepare solution sample in vial

A small amount of compound is added to a sample vial and solvent is added to create a solution of approximately five percent concentration.

▶ 02:37
6
Transfer solution to solution cell

The solution is transferred to a solution cell (two potassium bromide plates clamped together) until all air is expelled, then sealed with small plastic plugs.

▶ 03:33
7
Insert sample holder into spectrometer

The sample holder is positioned so that the grooved edges fit snugly into the spectrometer, placing the sample directly in the path of infrared radiation for spectrum recording.

▶ 04:07
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