Although these peaks look prominent, the peak area is very small, i.e. the related gas amount is very small. We attribute these features to gas bubbles trapped on their way from the counter electrode through the separator and electrolyte to the gas stream. While it would be a further improvement to the measurement to avoid these bubble formations, it shows how quickly the measurement system itself reacts to changes. An abrupt change in gas concentration, such as a popping bubble, results in a very sharp signal. This also means that signals with longer tails are not caused by slow gas transport, but rather the result of a longer gas evolution process.