Environmental Measurements Facility

GC User Info

  1. Staff Contact:  Doug Turner (650-678-6454)

  2. General: The GC is available to all members of the Stanford community.  This is a user run instrument.  Before signing up, users must complete the Radiation Safety Questionnaire, participate in a training session on the instrument and be certified by a facility technician.  The Radiation Safety Questionnaire is based on information available in the Stanford Radiation Protection Manual, as well as in the sealed source and Ni63 radionuclide safety data sheet.  Once certified, users planning to run samples must sign up on the GC Scheduler.  In addition, all users must fill out the user log book each time the machine is operated or modified.  The Shimadzu 2014 Instruction Manual and user log book are kept in a three ring binder on the shelf above the instrument. Users must wear safety glasses while operating this instrument. 

  3. Operation: The GC is available for use by certified users Monday through Friday, 8am to 5pm.  Once certified, arrangements can be made to use this machine during off hours.

  4. Cost:  The GC costs $25 per hour.  Due to the extended time necessitated for startup and shutdown of this instrument, only analysis time will be charged.  Analysis time includes injection of blanks and standards, as well as unknowns.  Users must have a valid Stanford PTA to sign up for this instrument.

  5. Samples: Only atmospheric air samples can be run on this instrument. A minimum of two mls of sample is needed per injection, although more is preferable especially if samples are variable in concentration. Wheaton vials that have been evacuated and filled with sample are less perishable and are the preferred means of collection.  In some cases, sample can collected and stored in a syringe and directly injected into the instrument.

  6. Standards:  The lab provides a low and high mixed standard for users:  Low (Nitrous oxide, carbon dioxide, and methane) and High (Nitrous Oxide: 1ppm, Carbon Dioxide: 605ppm, Methane: 5ppm) in Scotty disposable cylinders (17 L). Users in need of other standards will need to need to purchase those prior to using the instrument. 

Data: After analysis is complete, please remove your files from the instrument computer via email.  All data collected on the GC computer will be saved for at least 30 days. Files older than 30 days may be deleted to make space on the hard drive if needed.

You can get more detailed information by checking out our FAQ.