Traditional polysiloxane-type GC stationary phases degrade at elevated temperatures. The degradation process is well documented and consists of the thermal rearrangement of the siloxane backbone to produce cyclic groups. These groups are volatile and elute from the column as column 'bleed'. The silphenylene units (Fig. 1) within the 007-5MS backbone act as heat sinks and limit the formation of the cyclic groups normally associated with polysiloxane degradation.

The 007-5MS silphenylene columns offer the chromatographer a number of advantages: 
greater thermal stability,  resistance to oxygen degradation, fast ramping to elevated temperatures to purge the column of residual components, improved analysis of trace level compounds
less baseline bleed equals less baseline noise, which results in lower detection limits
increased column lifetimes, etc.