Infrared and near infrared spectrometers are always provided with sealed interferometer chambers carefully desiccated to protect their sensitive optical components from deterioration. It has been accepted from the earliest days of infrared spectroscopy that desiccation is only a poor compromise - the optical path should be either evacuated or purge with dry nitrogen. As the radiation passes from the source to the detector, it is attenuated by atmospheric H2O and CO2. The path length is measured in metres so however well the interferometer is desiccated the absorption is intense.
The most realistic solution is to fill as much as possible of the optical path with really dry nitrogen. Several methods of solving this problem are available - Permanent Dry Nitrogen laboratory supply - Liquid nitrogen boil off - compressed air dryers based on molecular sieves and sieves including CO2 removal but these solutions have invariably been expensive. As a result, most analytical spectroscopists have elected to compromise and use only desiccation. Thus, they frequently see CO2and H2O bands either positive or negative in their spectra and they see poor S:N rations in the 2000-1500 and circa 3000cm-1 regions. These in turn introduce errors in quantitation.
The solution is the Ventacon Series DG low cost dry nitrogen generator! The generator operates for about 1 hour between refills and provides a valuable facility for analysts. IT IS NOT INTENDED FOR THOSE WHO REQUIRE A PERMANENT FLOW OF DRY N2.