Commercial HPLC systems have been available for over 40 years now. During that time, a variety of technological advances have appeared, such as high-precision low-flow peristaltic pumps, injectors with superior reproducibility, and various types of detectors that enable highly sensitive detection. However, as a consequence, chemical factors are now becoming more important in determining whether high-sensitivity analysis or automated continuous analysis can be performed with high reliability or not. For example, this includes factors such as the adsorption and stability of sample components, the selection of mobile phases (or eluents), or addressing reproducibility problems with their preparation. It is also now necessary to be concerned with how dissolved air levels in mobile phases affect detector baseline stability or detection sensitivity.
Adjusting the level of dissolved air in mobile phases can be treated as a mobile phase degassing issue. Therefore, this special feature article has focused on degassing mobile phases by addressing issues ranging from theoretical principles to actual practice. I hope this article will be helpful in selecting and using a degassing method appropriate for your application.
(Initially published in 1991 as LCtalk Special Issue 5)