Static SIMS (SSIMS) is a powerful surface analytical technique which can provide detailed molecular information from organic surfaces. However, often much of the acquired information is too rich in detail and the data analysis relies on analysts' expertise and/or the limited number of materials in SSIMS libraries. Gilmore and Seah [Appl. Surf. Sci. 161 (2000) 465] recently developed a library independent technique, G-SIMS where extrapolation of the data to low surface plasma temperature reveals the un-degraded parent fragments from the SSIMS spectra. In this study, G-SIMS has been tested on biodegradable polyesters including: poly(glycolic acid) (PGA), poly(lactic acid) (PLA), poly(hydroxybutyrate) (PHB) and poly(caprolactone) (PCL). These materials are chosen to test G-SIMS capabilities on these structurally related compound series. The G-SIMS spectra derived from the SIMS spectra acquired from these polyesters yielded vital clues to fragmentation mechanisms as a function of molecular structure and highlight a powerful application of G-SIMS.