Why are NaCl and KBr used in sample preparation for Infrared Spectroscopy?

You can use KBr or NaCl only if your samples are hydrophobic, since these cell can be affected by samples soluble in water because KBr and NaCl are soluble in water and these cells can be broken.

How do you make a KBr pellet for IR?

Take about 1/8” of the solid sample on a microspatula and about 0.25-0.50 teaspoons of KBr. Mix thoroughly in a mortar while grinding with the pestle. If the sample is in large crystals, grind the sample separately before adding KBr. Place just enough spl. to cover bottom in pellet die.

What is KBr pellet method?

KBr Pellet Method. This method exploits the property that alkali halides become plastic when subjected to pressure and form a sheet that is transparent in the infrared region. Potassium bromide (KBr) is the commonest alkali halide used in the pellets.

Why KBr is used to make the pellet?

Potassium bromide (KBr, spectroscopic grade) is typically used as the window material because it is transparent in the IR, between 4000–400 cm-1. Alternatively, samples can be contained within a KBr matrix and pressed to form a pellet that is then analysed.

Which is the material used for preparation of pellets for solid samples of analyte in IR?

d) Pressed pellet technique – In this technique, a small amount of finely ground solid sample is mixed with 100 times its weight of potassium bromide and compressed into a thin transparent pellet using a hydraulic press. These pellets are transparent to IR radiation and it is used for analysis.

Why cell for the sample in IR spectrometer is made of KBr or nacl not of glass or quartz?

Because glass (i.e. quartz) would absorb in the IR spectrum, and mask the absorption of your sample.

What is KBr used in IR spectroscopy?

What is Nujol technique in IR spectroscopy?

To obtain an IR spectrum of a solid, a sample is combined with Nujol in a mortar and pestle or some other device to make a mull (a very thick suspension), and is usually sandwiched between potassium- or sodium chloride plates before being placed in the spectrometer.

What is KBr used for?

Bromide (potassium bromide [KBr] or sodium bromide [NaBr]) is a halide anticonvulsant used in veterinary medicine for the treatment of epilepsy.

What is the difference between KBR and KCl pellet spectra?

The red line is the KBr pellet method spectrum and the blue line is the KCl pellet method spectrum. The shapes of the spectra are clearly different near 3000 cm -1.

How do I know if my KBR pellet is contaminated?

1) Sample KBr pellet not clear. Lacks optical clarity. Sample damp, contaminated KBr powder or insufficient pressure when pressing. Dry the sample powder or sample and increase the pressure via the hydraulic pellet press. 2) Sample KBr pellet clear, but shows opaque spots.

Does ion exchange occur in hydrochloride samples using the KBR pellet method?

As shown above, as ion exchange occurs in some hydrochloride samples when analyzed using the KBr pellet method, the results of analysis by the KBr pellet method must be confirmed by some other analysis method.

How do I prepare a sample pellet for spectroscopy?

Dry the pellet powder or sample, check seals on the pellet die and lengthen evacuation period. To ensure that a sample pellet is produced which will enable accurate spectra of samples to be obtained, it is essential that the sample is thoroughly blended with the halide salt powder.