Designation:D3731−20StandardPracticesforMeasurementofChlorophyllContentofAlgaeinSurfaceWaters1ThisstandardisissuedunderthefixeddesignationD3731;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thesepracticesincludetheextractionandthemeasure-mentofchlorophylla,b,andc,andpheophytinainfreshwaterandmarineplanktonandperiphyton.Threepracticesareprovidedasfollows:1.1.1Spectrophotometric,trichromaticpracticeformeasur-ingchlorophylla,b,andc.1.1.2Spectrophotometric,monochromaticpracticeformea-suringchlorophyllacorrectedforpheophytina;andformeasuringpheophytina.1.1.3Fluorometricpracticeformeasuringchlorophyllacorrectedforpheophytina;andformeasuringpheophytina.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.SpecificprecautionarystatementsaregiveninSection8.1.4Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:2D1129TerminologyRelatingtoWaterD1193SpecificationforReagentWater3.Terminology3.1Definitions:3.1.1Fordefinitionsoftermsusedinthisstandard,refertoTerminologyD1129.3.2DefinitionsofTermsSpecifictoThisStandard:3.2.1chlorophyll,n—aclassofpigmentsinvolvedinpho-tosynthesis.3.2.2periphyton,n—microorganismsgrowingonsub-mergedobjects,commonlyconsistingofbacteria,algae,protozoa,androtifers.3.2...
