After this reference operation the gases were switched to
dry nitrogen (N2), and the anodic as well as the cathodic side
of the fuel cell were purged with 1.0 l min−1 at 30 ◦C. The
purging process continued until the high frequency resistance
at 1000 Hz increased by a factor of about 100 and more. Then,
N2 flow was switched off and the cell was cooled down.