Updated project metadata. Circulating antibodies provide valuable information about an individual’s immune status and constitute a significant portion of the human plasma proteome. Proteomic analysis of plasma is challenged by the large dynamic concentration range of plasma proteins, including antibodies. Peptide fractionation prior to data-independent (shotgun) proteomics has the potential to overcome this obstacle and enable increased coverage of plasma proteins. In this work, we evaluated the detection of tryptic immunoglobulin variable region peptides using multidimensional chromatography (high-pH preparative LC) or gas-phase ion mobility spectrometry (FAIMS). Typical digests of eight serum samples were obtained by (a) direct LC-MS (without prior fractionation, 1D), (b) LC-FAIMS-MS, and (c) high-pH reversed-phase fractionation into 24 fractions and subsequent measurement of each fraction. As de novo search is an essential step in antibody variable region peptide identification, all MS/MS spectra were acquired in high resolution Orbitrap mode.