Designation:D3870–91StandardPracticeforEstablishingPerformanceCharacteristicsforColonyCountingMethodsinMicrobiology1ThisstandardisissuedunderthefixeddesignationD3870;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticedealswiththeperformancecharacteristicsofenumerationmethodsformicroorganismsofhealthandsanitarysignificance.Theperformancecharacteristicscovermembranefilter,pourplate,andspread-platecolonycountingtechniques.Aperformancecharacteristicisaquantitative,experimentallydeterminedvaluethatisusedtoassessthesuitabilityofananalyticalmethodforagivenpurpose.Theperformancecharacteristicsdealtwithherearespecificity,includingselectivity,recovery,uppercountingrange,andprecisionandlowercountingrange.1.2Thepurposeofestablishingperformancecharacteristicsistoprovideasetofuniformpropertiestodescribebacterialenumerationtechniquesandselectivemedia.1.3Thisstandarddoesnotpurporttoaddressthesafetyproblems,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:D1129TerminologyRelatingtoWater23.Terminology3.1DefinitionsofTermsSpecifictoThisStandard:3.1.1lowerlimitofcountingrange—thatcountbelowwhichtheanticipatederrorbecomesunacceptablylargeinrelationtothecountitself.3.1.2precision—thedegreeofagreementofrepeatedmea-surementsofthesamesample.Theusualindexofprecisionisthestandarddeviation.3.1.3recovery—thedegreeofagreementbetweentheden-sityofmicroorganismsobtainedwithatestmethodandthedensityobtainedwithanacceptablereferencemethod.3.1.4selectivity—theabilityofamethodtoencouragegrowthofthetargetorganismwhileretardingdevelopmentonnontargetorganisms.Inthisway,overcrowdingproblemscanbeminimized.3.1.5sp...
