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Appendix C

Gas chromatograph detection limit analysis

  1. Using a heated 3 mL gas-tight plastic syringe, perform 2 mL injections of outside laboratory air (blanks) both at the start and end of each day’s sample analysis. Also run a blank injection immediately following any sample that produces an unusually high peak area. Expedition 329 blank vials containing ambient coring air are also run throughout analysis.
  2. Compile a list of all blank peak areas produced from injections of ambient coring air run throughout Expedition 329 sample analysis.
  3. Calculate the average blank peak area from this compilation and use this value for the blank correction of measured peak areas.
  4. Calculate the standard deviation of all blank peak areas.
  5. The detection limit for blank corrected samples equals three standard deviations of all blank peak areas.