While back-exchange levels unsurprisingly vary across peptides, hardly any differences are observed when comparing the same peptide between the two systems (Figure ). This similitude is also reflected by the calculated average of back-exchange, which accounts for 30.02 ± 0.26 % in the standard two-valve and 30.34 ± 0.63 % in the extended three-valve configuration (Table ). The assessment of peptide carry-over also highlights that the delipidation system performs equally well as compared to the standard HDX-MS system, with a total average of 0.77% (85% of all peptides show less than 1% carry-over) for both systems.