Designation:D1979–97StandardTestMethodforFreeFormaldehydeContentofAminoResins1ThisstandardisissuedunderthefixeddesignationD1979;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationoffreeformaldehydeinaminoresinsandtheiraqueousandnon-aqueoussolutions.Aminoresin-freeformaldehydelevelsfromabout0.02to5.0%canbedeterminedbythistestmethod.Theapplicabilityofthistestmethodtoothermatricesisunknown.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:D1193SpecificationforReagentWater2D1959TestMethodforIodineValueofDryingOilsandFattyAcids33.SummaryofTestMethod3.1Specimensaremixedwithboratebuffersolutionandicewater,thenkeptcoolinanicebath.Excesssodiumsulfiteisaddedtoconsumefreeformaldehydeasfollows:CH2O1Na2SO31H2O→HOCH2SO3Na1NaOH(1)3.2Theexcesssodiumsulfiteisremovedbytitrationwithiodineusingstarchastheindicatorasfollows:Na2SO31I21H2O→Na2SO412HI(2)3.3Thesodiumsulfite-formaldehydecomplexisthende-composedwithsodiumcarbonatetoquantitativelyregeneratesodiumsulfiteandformaldehydeasfollows:HOCH2SO3Na1Na2CO3→CH2O1Na2SO31NaHCO3(3)3.4Theliberatedsodiumsulfiteistitratedwithiodine(Eq2)andfreeformaldehydeiscalculatedfromthissecondiodinetitration.4.SignificanceandUse4.1Theamountoffreeformaldehydeinaminoresinsmaybeofconcerntobothproduceranduser,asitspresenceinairabovethresholdamountsmayproduceobjectionableodorsandirritanteffects.Thistestmethodcanbeusefulforevaluatingsuppliers’productsandforqualitycontrol.5.Apparatus5.1AnalyticalBalance,60.1mg.5.2MagneticStirrerandStirBar—A“heavyduty”mag-neticstirrerisnecessary.5.3B...
