Degassing device

A degassing device comprising:

• a chamber evacuated by a vacuum pump;
• and a degassing tube housed in the chamber and made of a gas-permeable material allowing gas to pass through while preventing liquid from passing through, the degassing tube having a wall surface through which gas contained in liquid flowing through the degassing tube is taken out to be discharged;
• and the degassing device further comprising:
• a) an absorbance measurement section that includes a flow cell through which the liquid flows, a light-casting unit using a semiconductor light-emitting element as a light source for casting measurement light into the flow cell, and a photodetector for detecting light resulting from transmission of the measurement light through the flow cell;
• b) a passage-switching section switchable between a first passage through which the liquid introduced into the degassing device flows into the flow cell after passing through the degassing tube and a second passage through which the liquid introduced into the degassing device flows into the flow cell without passing through the degassing tube;
• and
• c) a signal processor for calculating a piece of information reflecting degassing performance or for determining the degassing performance, based on a first detection signal obtained by the photodetector of the absorbance measurement section with the first passage formed by the passage-switching section, and a second detection signal obtained by the photodetector of the absorbance measurement section with the second passage formed by the passage-switching section.