To prepare samples for IR spectroscopy, different techniques can be used depending on the sample form:
1) Liquid samples:
- Place a drop of the liquid on a highly polished salt plate (such as NaCl, AgCl, or KBr).
- Place a second salt plate on top of the first one to spread the liquid in a thin layer between the plates.
- Clamp the plates together to hold the sample in place.
2) Solid samples:
a) Mull technique:
- Finely crush the solid sample.
- Mix the crushed sample with a mulling agent (such as Nujol) in a marble or agate mortar using a pestle to make a thick paste.
- Apply a thin film of the paste onto salt plates.
- Mount the plates in the path of the IR beam and record the spectrum.
b) Solid run in Solution:
- Dissolve the solid sample in a non-aqueous solvent, ensuring that there is no chemical interaction with the solvent and the solvent is not absorbed in the range to be studied.
- Place a drop of the solution on the surface of an alkali metal disc.
- Evaporate the solvent to dryness, leaving a thin film of the solute.
For solid samples, other techniques like the KBr pellet method and the Nujol method can also be used. The KBr pellet method involves pressing the powdered sample into a disc using a specific ratio of KBr to sample and a pressing load. The Nujol method involves mixing the powdered sample with a mulling agent to form a paste, which is then applied onto salt plates.
It's important to note that the material used for sample preparation must be transparent to IR radiation, hence the use of salts like NaCl, KBr, and AgCl. Additionally, for powder samples, measurement methods such as the diffuse reflection method, attenuated total reflection (ATR), and the classic KBr pellet method are commonly used.
Looking for reliable laboratory equipment for IR spectroscopy? Look no further than KINTEK! Our high-quality salt plates and alkali metal discs are perfect for preparing liquid and solid samples for accurate IR spectrum recording. Trust KINTEK for all your laboratory equipment needs. Visit our website or contact us today to place your order!
