* Cost of reactor and replacements (each replacement unit costs ~ $6000) 
* Addition of dead volume causes an increase in peak broadening depending on the GC column flow rates and molecule types (5-10% broadening is typical)
** Heteroatoms and oxidation of Polyarc transfer lines increase this broadening
* Susceptible to sulfur, silicon, and halogen poisoning
* Requires constant feed of hydrogen
* Cannot be regenerated in-house; must be shipped back to the manufacturer for a replacement
* Cannot be used with cryogenic oven temperatures, or for GCxGC
* Poor response for species containing C-F bonds
* May contribute to power overload on older GC models, preventing the use of other heated components such as valve boxes or auxiliary detectors