What are they?
The main gases dissolved in purified water are oxygen and nitrogen, carbon dioxide, plus traces of inert gases all in equilibrium with ambient air.
Where do they come from?
Dissolved oxygen and nitrogen and inert gases will pass straight through reverse osmosis membranes.
Which Applications do they effect?
Dissolved gases can alter pH of laboratory water and upset ionic balance. High concentrations od dissolved gases can cause bubble formation hampering flow through columns e.g., HPLC.