It isdifficult toestimatehowlongitwillrequireasolutionofto
be apurgedofavolatiledissolvedgasasthisdependsonmany
factors suchasbubblesize,gas flow rateandtheoperativeHenry’s
lawconstant(KH). Forgaseswithahigh KH, suchasNH3,
quantitativepurging(499%) requiresatimetoolongtobe
practical foranalysis.MeasurementofresidualNH3=NHþ
4 in the
GCU solutionafter200sofbubblingunderthestatedconditions
suggestedthat 15%atroomtemperature(28 1C )onaverageis
removedandthisprovidessatisfactoryresultsundertheproposed
procedure.