Sampling of Solids: 

As most of the organic compounds absorb widely within the mid IR region, it becomes hard to search a suitable solvent whose signals would not interfere along with those of the sample. Within such case it becomes almost necessary to analyse the solid itself. There are two methods for handling a solid sample. These are as follows:

• Mull technique
• Pelleting with KBr

Mull technique: In this method called Nujol mull technique, the sample is finely ground to a paste in a small amount of mineral oil hexachlorobutadiene (nujol). It creates a fine suspension or mull of the sample in the oil. The mull is pressed between two NaCl or KBr plates to provide a thin film of the sample. The two plates are then clamped in a holder along with open windows on both sides and the assembly is kept within the path of the infrared beam.