Designation:D7847−22StandardGuideforInterlaboratoryStudiesforMicrobiologicalTestMethods1ThisstandardisissuedunderthefixeddesignationD7847;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONMicrobiologicalparameterspresentanumberofuniquechallengesrelativetochemicalandphysicaltestmethodsaproposofthedevelopmentofprecisionandbiasterms.AnumberofthesechallengesarediscussedinGuideE1326.Asaworkinggroup(WG)wefirstgrappleddirectlywithsomeoftheseissuesduringthedevelopmentofPracticeD6974.ThedraftsballotedattheD02.14subcommitteelevelinFebruaryandJune2002,wereballotedwiththedocumentidentifiedasaMethod.Moreover,theproposedMethodwasdraftedasaharmonizeddocumentwiththeEnergyInstitute’s(EI)MethodIP385.WhentheitemwasballotedatD02level,membersofD02.94compelledustochangethetitlefromMethodtoPractice.TheargumentwasthatASTMMethodslistsingleseriesofstepsthatleadtoameasurableresult(abitofdata;quantitative,semi-quantitativeorqualitative).BecauseD6974providesfortheselectionofdifferentsamplevolumes(basedontheestimatedculturablepopulationdensity)anddifferentgrowthmedia(basedonthesub-populationtobequantified),itwouldonlybeacceptedasanASTMPractice;notaMethod.Thisissueofperforminginterlaboratorystudiesforculturemethodswillbediscussedbelow.SincePracticeD6974wasapproved,fourmicrobiologicaltestmethodshavebeenapprovedbyASTM:D7463,D7687,D7978,andD8070.Becausethesemethodsmeasuretheconcentrationofabiomarkermoleculeormicroorganisms,theissuesthatarerelevanttoILSaresimilarto,butsomewhatdifferentthanthosethataffectILSforculturemethods.Beckers2investigatedmicrobiologicaltestmethodinterlaboratorystudies,butadvisedseveralmeasuresthatareeitherimpracticalforornotrelevanttothemethodsthathavebeendevelopedwithinD02:(1)Freezeinoculatedsamplesafterdispensingintoportionsforshipmenttoparticipatinglabs;(...
