US Geological Survey
The Reston Chlorofluorocarbon Laboratory
Dissolved Gases Frequently Asked Questions
- What gas analyses are available?
Different analyses are available including methane by itself,
helium-4 by itself, and a package including N2,
Ar, CH4, O2, CO2
- What media can
be analyzed?
Gas and Water
- Why
collect samples for N2, Ar, CH4, O2,
and CO2?
- Why do I need
to collect dissolved gases in duplicate?
All dissolved gas samples are normally analyzed in duplicate.�
This provides the user with some QA/QC information.
- Do I have to
pay for duplicate samples?
No.
- Can I pre-pay
for analyses?
Yes.
- How
do I collect samples for dissolved gases?
-
What Standards are used to analyze samples for dissolved gases?
- How long can
I keep the bottles before shipping?
Samples should be shipped within several days of collection.
- How should the
samples be stored before shipping?
Store under refridgeration (approximately 4 ºC; Caution:
Do not freeze the sample) or preferably, on ice, until shipping.�
This will minimize expansion of the water on warming which
could cause the stopper to come out of the bottle.� This will
also minimize microbial activity that can affect dissolved
oxygen, carbon dioxide, and even nitrogen and methane in the
sample.
- Can I put labels
on the sample bottle?
No.� The bottles have been weighed in the lab before shipping
to you.� The label would change the weight of the bottle.�
You can put the label on the sleeve that holds the bottle.
- Can I change
stoppers used on the bottle?
No.� The stopper has been weighed in the lab and belongs with
the bottle it came with.
- What do I do
if there is a bubble in the bottle?
If the bubble was introduced during collection, empty the
sample and repeat the collection.�
- What if a bubble
forms in the bottle during shipping or storage?
This is normally not a problem.
- I�m having trouble
getting the stopper to go into the bottle.� How far do I have
to get it in the bottle?
At least half
way.� Do not use any lubricant on the stopper.
- How do I dispose
of the used needles?
You May return needles to the Dissolved Gas Lab, or dispose
of them in accordance with OSHA regulations.� You may place
the used needles in one of the extra bottles provided and
return that bottle with your samples so that the Dissolved
Gas Lab can dispose of the used needles through proper channels.
Dissolved Helium Frequently Asked Questions
- Why
do I need to sample dissolved Helium in ground water?
- Why do I need
to collect dissolved Helium in duplicate?
The duplicate sample is a backup in case of analytical problems
in the lab, and also some samples are analyzed in duplicate
to provide the user with some QA/QC information.
- Do I have to
pay for duplicate samples?
No.
- Can I pre-pay for analyses?
Yes.
-
How do I collect dissolved helium samples?
- What Standards
are used to analyze dissolved Helium?
Two standards are used.� One is air and the other is nitrogen
containing 35 ppmv of helium.
- How long can
I keep the bottles before shipping?
Samples should be shipped within several weeks of collection.
- How should
the samples be stored before shipping?
Store under refridgeration or on ice until shipping.� This
will minimize expansion of the water on warming which could
cause the stopper to come out of the bottle.
- Can I put labels on the sample bottle?
No.� The bottles have been weighed in the lab before shipping
to you.� The label would change the weight of the bottle.�
You can put the label on the sleeve that holds the bottle.
- Can I change stoppers used on the bottle?
No.� The stopper has been weighed in the lab and belongs with
the bottle it came with.
- What do I do if there is a bubble in the bottle?
If the bubble was introduced during collection, empty the
sample and repeat the collection.
- What if a bubble forms in the bottle during shipping or storage?
This is normally not a problem.
- I�m having trouble getting the stopper to go into the bottle.� How far
do I have to get it in the bottle?
At least half
way.� Do not use any lubricant on the stopper.
- How do I dispose of the used needles?
Return all needles to the Dissolved Gas Lab.� Put the plastic
cap over the end of used needles and put inside the sleeve
around the sample bottle. The Dissolved Gas Lab will dispose
of the used needles through proper channels.