Comment on “Evaluation of the Tenax Trap in the Sample Analysis at Mars Instrument Suite on the Curiosity Rover as a Potential Hydrocarbon Source for Chlorinated Organics Detected in Gale Crater” by Miller et al. (2015)

Miller et al. [2015, https://doi.org/10.1002/2015JE004825] described the result of experiments testing the potential of Tenax TA, a polymer used on Sample Analysis at Mars (SAM), as a source of chlorinated benzene. Miller et al. [2015] conclude that the amount of chlorobenzene produced is low and that Tenax TA cannot be the source of the chlorobenzene observed on Mars by SAM. Miller et al. [2015] did not provide the identification of two unknown compounds produced during these pyrolysis experiments, though their abundance is orders of magnitude higher than that of chlorobenzene. Here, we tentatively identify these compounds based on the mass spectra provided by Miller et al. [2015], the most abundant of which is a chlorinated monomer of Tenax TA. This chlorinated monomer is likely to accumulate in the hydrocarbon Tenax trap and in the transfer line between the trap and the mass spectrometer. Further breakdown of these compounds could lead the high background of chlorobenzene observed on Mars.