Figure 1: Overview about the LC-MS data processing steps of ICPL_ESIQuant. The example shows an ICPL quadruplex peak pattern in three dimensions (m/z, RT and intensity): 1. Peak picking recognizes peak profiles in the raw data and converts it to peak m/z centroids (single sticks); 2. Deisotoping recognizes peptide isotope pattern (including overlapping peptide pattern) and reduces each peptide pattern to its monoisotopic centroided peak; 3. Quantification integrates the chromatographic elution profile of each peptide, which results in one single intensity value represented as a single stick. In order to detect ICPL multiplets in the data, the algorithm checks the known mass distances (in Dalton) between the peptide signals as well as the isotopic effect introduced by deuterated labels ICPL4 and ICPL10 (detailed information in [11]).