HPAEC-MS experiments were performed on a Dionex BioLC chromatograph, with an AS-50 autosampler, a GS-50 gradient pump and an EG-50 eluent generator. The mobile phase was on-line generated KOH at 0.25 ml min−1. The hydroxide concentrationwas programmed as follows: 10mM during 22 min, 10–100mM in 1 min, 100mM during 7 min, 100–10mM in 0.5 min and column equilibration at 10mM during 10 min. The analytical column was a Dionex Carbopac PA-20 (3mm×150 mm) with a PA-20 guard column (3mm×50 mm) at 30 ◦C. The desalter was an ASRS-Ultra with a constant current of 65 mA. The post-column addition of 0.5mM LiCl was done with a Dionex AXP-MS auxiliary pump.MSdata were acquired on a FinniganMSQquadrupole spectrometer with an electrospray interface (ESI). The probe temperature was fixed at 500 ◦C with a needle voltage of 3.5 kV.