Sampling Devices:

The handling of sample for the measurement of IR spectra is not easy. Firstly since unlike UV-VIS spectrometry, glass or quartz cannot be used as a material for making cuvettes to be used in the infrared region. It is so since glass absorbs tightly at most of the frequencies in this region. Another, analysing an analyte as a solution is also not simple because most of the solvents of the organic compounds themselves absorb in several regions of the IR spectrum. Actually there is no solvent which is transparent within the whole range.

In the absence of glass, the salts such as NaCl and KBr that are transparent in the IR region are used for the construction of the cuvettes. These cuvettes are known as IR windows. The NaCl windows are most generally used for routine work in the region4000-650 cm as these are cheaper than KBr windows. Therefore, for measurements below 650 cm^-1, the KBr cells are the right choice since NaCl starts absorbing in this region.

The sampling methods depend upon the phase (solid, liquid or gas) of the sample being analysed.