It is important to remember that in the analysis of synthetic polymers, ionization is generally not achieved by direct excitation of the analyte, but requires the presence of a cationization reagent, usually a Lewis acid metal cation, which reacts with the soft Lewis base of polymers such as double bonds or phenyl rings to form an [M+cation] + adduct. To take into account the mass of these adducts and group the peaks into series, based on the mass difference between the peaks, giving a linear function, the spectra were analyzed using Polytool1.18 software, which has been developed for this objective. In the PBPAC spectrum, two series of peaks can be detected, separated by the molar mass of the repeating unit (254.28 g•mol -1 ), identified as the "A" and "B" series. The constant term of this affine function represents the residual molar mass of the adduct, i.e. the molar mass of the cation (Na + ) added to the molar mass of the end groups. The molar masses of the end groups calculated by Polytool1.18 for the A and B series are close to 0 and 196 g•mol -1 respectively, and represent 38 % and 62 % of the polymer peak intensity. Series A therefore corresponds to cyclic PBPAC, as there is no additional end-group. The end groups in the B series can be identified as two 4-cumylphenol units, with a molar mass of 450.6 g•mol -1 . However, Polytool1.18 groups the peaks according to the repeating unit, in which case a polymer of size n made up of these end groups is considered by Polytool1.18 as a polymer of size n+1, giving an end group with a molar mass of 196.3 g•mol -1 . Note that the presence of the monomer 4-cumylphenol is expected, as it is a capping agent commonly used to stop the polymerization reaction. Secondly, it is important to point out that the mass range taken into account by Polytool1.18 for spectra processing has an impact on the values returned. Indeed, the instrument is calibrated on the first 6000 Da of the spectrum, beyond which peak intensity is too low to be used for accurate calibration with Flex Control software in our conditions. When the spectra are processed over the calibrated range, on 20 samples, the average molar mass of the end groups is 196.49 ± 0.17 g•mol -1 . When the whole spectrum is then taken into account by polytool1.18, a shift in masses is observed, with the average molar mass of the end groups being 194.45 ± 0.32 g•mol -1 . Finally, when only the peaks that are beyond the calibrated range are considered, the shift is even greater, with an average end group molar mass of 193.08 ± 0.43 g•mol -1 , which shows how they effectively influence the calculated mass. It is therefore necessary when developing a polymer MALDI-TOF analysis method to precisely define the calibrated m/z range, a parameter which is often not specified, and to focus mass analysis only on the latter. Finally, it is important to note that the mass range analyzed here by MALDI-TOF is lower than the molar mass distribution of the polymer, in fact only masses below 15000 m/z can be detected. Consequently, we must state that the results obtained are only partial. Nonetheless, it is widely accepted in the literature that high masses are discriminated in favor of low masses in MALDI mass spectrometry, particularly in the case of polymers with high degree of polymerization (DP) and polydispersity greater than 1.2 or 1.5. As a result, high masses fall outside the instrument's analysis range, and quantification of the final groups based on peak intensity can only be partial, which remains one of the main limitations of this technique.