ASTM 3612/TOGA/DissolvedGasGC
RevisedOctober 2013
When gases are dissolved in liquids the concentration of those gases can be de-
scribed by the volume of gas in a volume of water ( volume% ) or byweight of gas in
aweight of liquid, or volume of liquid, or bymoles. There is a very large difference
between volume%, weight% andmole%. Volume% is themethodmany people use.
For example:
From the Internet we learn that theweight of CO2 in 100ml of water when completely
saturatedwith a pureCO2 purge gas is 0.169grams. Bymultiplying this by a series
of unit conversionswe get 1.45ml CO2 in everyml of water, or 145%. If our calgas
contains1%CO2 ( which it does in this case ) then thewater would contain 1.45%
CO2 ( 14,500ppm ) by volume.
Byweight% the answer comes out to be 16.9 ppm
Bymole% the answer comes out to be 1.08ppm
So there is at least a factor of 10000 difference between vol% andmole%
Volume% calculation assuming 100%CO2 at 1 atm and saturated
.169gramCO2 1moleCO2 24litersCO2 1000mlCO2 = 1.45ml CO2
100mlH2O 28gramCO2 1moleCO2 1literCO2 1.00ml H2O
*Gramsof gasdissolved in100gofwaterwhen the total pressureabove the soluƟon is 1atm.
Oxygen .0043
Acetylene
.117
Nitrogen .0019
Hydrogen
.00016
Methane .0023
CO
.0028
CO2
.169
Ethane
.0062
Ethylene .0149
Reference: G.W.C. KayeandT.H. Laby, "Tablesof Physical andChemical Constants,"15thed., Longman,NY, 1986, p. 219
