For a complete understanding of the raw material used for cosmetic surgery under uncontrolled medical conditions, an unknown sample of polydimethylsiloxanes has been investigated utilizing a combination of analytical techniques: pyrolysis/gas chromatography/mass spectrometry (Py/GC/MS), electrospray ionization (ESI)-MS, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF)MS, and liquid chromatography (LC)/MS. Among these techniques, the LC/APCI-MS coupling allowed the fastest and more effective analysis. In addition, the complexity of the mass spectra deduced from these LC/MS experiments was simplified compared to the mass spectra obtained by MALDI-TOF. In this work, we have demonstrated how the LC/APCI-MS coupling applied to polydimethylsiloxane samples permits the full characterization of samples where end groups of different nature can be present in very small quantities.