SOP for Field Collection of Air Samples for GC/MS Analysis of Mercury Compounds

  1. Only handle sample collection devices with gloved hands—make sure gloves are clean and new.
  2. Collect samples as high above ground as possible. Samples must be collected from 3 m above ground at a minimum.
  3. Give each sample a unique sample ID, following the naming convention shown in the log sheets. Use labeling tape and a permanent marker to label each tube with this ID.
  4. For sample collection devices comprised of quartz wool packed in a 10” long, 0.5” diameter PFA Teflon tube, pull ambient air directly into the tube. Do not attach a filter of any kind upstream of the quartz wool-packed tube. Remove any Teflon tape from the ends of sample collection devices before pulling any air through them.
  5. Attach a pump to the downstream end of the sample collection device. Quartz wool-packed tubes may have a silicone tube attached to one end. If so, this is the downstream end, and the silicone tube should be fitted over another tube that connects to the pump. If no silicone tube is attached to one end, mark with labeling tape or a Teflon-marking pen which end of the tube is used as the downstream end.
  6. The pump used should be capable of pulling at least 10 liters per minute of air through the tube. A pump that pulls up to 30 liters per minute may be better. Data collected from these tubes will be only semi-quantitative, so the flow doesn’t need to be precisely controlled. In general, more flow is probably better, up to about 30 liters per minute. The flow should be checked before sampling with a suitable flow measurement device.
  7. If using quartz wool-packed tubes as sample collection devices, it may be advisable to install a filter downstream of the tubes to collect any quartz wool bits that come out of the tube. Quartz wool bits may damage sampling pumps.
  8. It may be desirable to cool the sample collection devices below ambient temperature to aid in collection of oxidized mercury compounds. This can be accomplished by enclosing the collection devices in an ice bath. Ensure before doing this that the dewpoint of the air to be sampled is below 0°C. If the sample collection devices are placed in an ice bath, make sure the upstream end protrudes at least an inch or so from the ice bath to minimize the amount of mercury lost on the ice bath surfaces.
  9. Sample collection times may vary, but for now we think collection times of 2-4 hours will probably strike the best balance between keeping sampling times short to minimize oxidized mercury compound decomposition and keeping sample times long to increase the amount collected.
  10. Record detailed notes on the log sheets about the atmospheric and other conditions during sampling, how the sampling occurred, anything that went wrong, etc.
  11. After sample collection is complete, IMMEDIATELY disconnect the sample collection devices from the pump(s), wrap their ends in Teflon tape, and transfer the sample collection devices to a freezer. The sooner the samples are moved to a freezer the better. It is probably desireable to have a cooler with ice or even dry ice at the sampling location, so the samples are cold even in transit back to an electric freezer. A deep-freeze freezer is probably better than a normal one.
  12. If shipping the samples back to the USU lab, ship the samples on dry ice. Ground shipping from Nevada may be as fast as 2-day express shipping, but that should be verified with the carrier. With dry ice, a 2-day shipping time is probably adequate. Notify USU of shipments and please provide tracking numbers so samples do not sit and get warm. Ship samples to:

Seth Lyman

Utah State University

320 N. Aggie Blvd.

Vernal, Utah 84078

You can use the phone number (435) 630-1433