Figure 3.

Adjustment of abundances of CA fragments improved the concordance between top-down and bottom-up quantification. (A) Uncorrected intensities of CA fragments at different NCE (inset) in MS/MS spectra of four PC species (indicated below the bars). Lines above the bars indicate the sum of intensities of sn-1 and sn-2 fragments; shaded parts of the bars stand for intensities added by accounting for the products of CO₂ loss. Gray shaded bars indicate the intensities of intact precursor peaks in the FT MS spectrum. (B) Correlation plot of lipid standards quantified by FT MS and by HCD FT MS/MS. (C) The intensities of the same CA peaks after LipidXte correction. (D) Correlation plot after LipidXte correction.