To maintain quality of insulating materials over a long period, inhibition of yellowing is one of the most important challenges. However, the analysis of yellowing is difficult owing to the small amount and complex mechanism. Therefore we considered a new advanced method to clarify the cause of yellowing by Pyrolysis GCxGC-MS coupled with multivariate data analysis. The experiments described in this poster demonstrates an advanced method which enables the correct peak identification; it is possible to distinguish minor characteristics with ultralow volume samples. And the collection of full mass range TOFMS data allowed for measuring both targeted and non-targeted analytes. Additional collection of HR-TOFMS data allowed for the confirmation of analyte identity with mass accuracies of ≤1 ppm and for determining information about analytes that were previously unknown like pyrolysate.