Is the DDT and Endrin breakdown check in Method 8081 required if not analyzing for those compounds? For example, is this needed if just analyzing for Toxaphene or Chlordane?
Yes, the DDT and Endrin breakdown check for Method 8081B is still required. The degradation check demonstrates that the instrument injection port is inert (not contaminated with high boiling point residues). This contamination can have negative effects beyond just the breakdown of DDT and Endrin.