Source for gas detection ampoules

I'm looking for a sources of gas detection ampoules.  Specifically,
for detecting nitrate outgassing, but for gas detection in general.
These are thin tubes which have the ends scored, snapped off and
then the subject gas is drawn through the tube with a hand-operated
vacuum pump.

Tim Vitale
Preservation Associates
831-684-2731

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                  Conservation DistList Instance 12:53
                Distributed: Thursday, December 17, 1998
                       Message Id: cdl-12-53-008
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