Transfer of CO2, N2O and CH4 to butyl rubber (polyisobutylene) septa during storage.
Greenhouse gases are more sampled than ever because of environmental interests. Gas samples are often inserted into vials with gas tight butyl rubber septa before concentration analysis. Little is known on the global transfer property of butyl rubber septa for CO2, N2O and CH4. Sorption kinetics were measured by injecting CO2, N2O or CH4 into glass vials with either one of four butyl rubber septa types and stored during 90 days. CO2 and N2O concentrations decreased during storage depending upon septa type and initial concentration, with the highest linear rate being 0.023 for CO2 and 0.0015 mg L(-3) day(-1) for N2O. When a low concentration was injected, CH4 concentration changes over time were small and did not differ between septa types. Sorption isotherms were measured using nine concentrations and stored during 45 days. CO2 sorption isotherms ranged from 0 to 3.7 x 10(-3) m(3) m(-2) and N2O from 0.3 to 1.4 x 10(-3) m(3) m(-2). Examples of errors associated with the use of these butyl rubber septa are given.
Horticultural Research Center, Université Laval, 1980 Hochelaga, Québec, G1K 7P4, Canada.
Sébastien F
SF
Lange
Suzanne E
SE
Allaire
Eric
E
van Bochove
D000042:Absorption; D000393:Air Pollutants / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D020724:Elastomers / Q000737:chemistry / Q000378:metabolism*; D004784:Environmental Monitoring; D017752:Greenhouse Effect; D007700:Kinetics; D008697:Methane / Q000032:analysis*; D009609:Nitrous Oxide / Q000032:analysis*; D011090:Polyenes / Q000737:chemistry / Q000378:metabolism; D011108:Polymers / Q000737:chemistry / Q000378:metabolism; D018570:Risk Assessment; D013816:Thermodynamics
D000393:Air Pollutants; D020724:Elastomers; D011090:Polyenes; D011108:Polymers; D002245:Carbon Dioxide; C008967:polyisobutylene; C017098:butyl rubber; D009609:Nitrous Oxide; D008697:Methane