The invention relates to a method and apparatus for evaluating reaction molecular byproducts of pyrotechnic reactions. A closed calorimetry bomb holds pyrotechnic material, which is detonated by a charge. The calorimetry bomb is vented directly into a gas chromatography machine, where gas phase molecules are separated based on their polarity. The separated molecules are then injected into a mass spectrometer and characterized by their mass fragmentation. The remaining residual solids within the bomb are extracted and injected into a liquid chromatography instrument where they are separated by their polarity. The separated molecules are then injected into a mass spectrometer and characterized by their mass fragmentation pattern. The method provides a complete picture of the reaction pathways and products to aid in regulatory compliance of incorporating energetic materials into real-world applications, particularly those in the family of PFAS containing compositions.