The CE setup for the untargeted metabolomics profiling was the same as described in section 4.1.5 for the validation. The CE system was in turn hyphenated to a maXis-3G QTOF MS from Bruker (Bremen, Germany), equipped with an ESI source via a coaxial sheath-flow ESI interface with a standard triple-tube sprayer (Agilent P/N G1607A) and a platinum needle. The sheath liquid was delivered at a flow rate of 3 µL/min, using a 2300 Series isocratic pump purchased from Agilent Technologies (Waldbronn, Germany) equipped with a 1:100 split.