Identification of Unknown Outgassing Species Using Gas Chromatography-Mass Spectrometry

Curtis Mowry, Lance Miller, Adam Pimentel, Ray Fuentes

Sandia National Laboratories

Chemical species can be released, or outgassed, from materials such as polymers, epoxies, or foams. These species can be unreacted starting materials or the product of complex decomposition reactions and once released can interact with other materials. A conformal coating was discovered to outgas which created concern regarding aging and interactions with other materials. To understand the risk, experiments were undertaken to identify specific products and quantities. Outgassing was assessed after various treatments (heat, vacuum, etc.) which would mitigate some source terms and is a common strategy for certification by manufacturers and those performing outgassing measurements. One major outgassed product detected in GC/MS (gas chromatography with mass spectrometry detection) experiments, however, was assigned with high confidence as two different species by two labs. Strange? Yes. In this situation it was possible for the measurement method to alter the measured species, so identification confidence based on library spectral matching was high. We will discuss the tools and process that demonstrates both labs were correct! This situation highlights the need sometimes to perform additional experiments to identify a true unknown species involved with critical materials and component investigations. We must remember that any analytical method is only detecting a small subset of the chemical space. Various authors are attempting to define the process of generating and communicate true “confidence” for GC/MS data [1,2]. Details and discussion of the Uvikote story are presented in this context of identifying unknown outgassed products.
1. Milman, B. L.; Zhurkovich, I. K., The chemical space for non-target analysis. TrAC Trends in Analytical Chemistry 2017, 97, 179-187.
2. Schymanski, E. L.; Jeon, J.; Gulde, R.; Fenner, K.; Ruff, M.; Singer, H. P.; Hollender, J., Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence. Environ Sci Technol 2014, 48 (4), 2097-8.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.