Designation:D4137−82(Reapproved2012)StandardPracticeforPreservingPhytoplanktonSamples1ThisstandardisissuedunderthefixeddesignationD4137;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticedescribestheproperprocedureforpreserv-ingphytoplanktonsampleswitheitherformaldehydeorLugol’ssolution1.2Thisstandarddoesnotpurporttoaddressallofthesafetyproblems,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocument2.1ASTMStandards:2D1193SpecificationforReagentWater3.SummaryofPractice3.1Aphytoplanktonsamplecollectedwitheitheraqualita-tiveorquantitativesamplerispreservedwitheitherformalde-hydesolutionorLugol’ssolution.4.SignificanceandUse4.1Formaldehydesolutioncanbeusedasapermanentpreservativeofalgae.Lugol’ssolutioncanbeusedtopreservealgaeforuptooneyear.Lugol’sisamoresuitablepreservativefordelicatealgaesuchasnakedflagellates.5.Reagents5.1PurityofReagents—Reagentgradechemicalsshallbeusedinalltests.Unlessotherwiseindicated,itisintendedthatallreagentsconformtothespecificationsoftheCommitteeonAnalyticalReagentsoftheAmericanChemicalSocietywheresuchspecificationsareavailable.3Othergradesmaybeused,provideditisfirstascertainedthatthereagentisofsufficientlyhighpuritytopermititsusewithoutlesseningtheaccuracyofthedetermination.5.2PurityofWater—Unlessotherwiseindicated,referencestowatershallbeunderstoodtomeanreagentwaterasdefinedbyTypeIIofSpecificationD1193.5.3CupricSulfateSolution(saturated)—Dissolve21gofCuSO4in100mLofwater.5.4DetergentSolution(20%)—Dilute20mLofhouseholdliquiddetergentto100mLwithwater.5.5FormaldehydeSolution,37to40%aqueous.5.6Lugol’sSolution—Dissolve60gofpotassiumiodideand40gofiodinecrystalsin100...
