LipidXplorer supports the interpretation of spectra acquired using different mass spectrometers. (a) Comparison of the relative abundances of 24 major PE and PG lipid species identified in a total E. coli extract in MS and data-dependent MS/MS modes on the LTQ Orbitrap Velos (red bars) and QSTAR Pulsar i (blue bars) mass spectrometers, while spectra were interpreted by LipidXplorer. The same extract was analyzed by MPIS on the QSTAR Pulsar i and LipidProfiler software (green bars). Species abundances were normalized to the total abundance of the lipid class; error bars (standard deviation) were calculated on the basis of six experiments. Correlation coefficients and slopes of scatter plots for each pair-wise comparison are presented in Table 5.