Designation:D4691−17StandardPracticeforMeasuringElementsinWaterbyFlameAtomicAbsorptionSpectrophotometry1ThisstandardisissuedunderthefixeddesignationD4691;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thispracticecoversgeneralconsiderationsforthequantitativedeterminationofelementsinwaterandwastewaterbyflameatomicabsorptionspectrophotometry.Flameatomicabsorptionspectrophotometryissimple,rapid,andapplicabletoalargenumberofelementsindrinkingwater,surfacewaters,anddomesticandindustrialwastes.Whilesomewatersmaybeanalyzeddirectly,otherswillrequirepretreatment.1.2Detectionlimits,sensitivity,andoptimumrangesoftheelementswillvarywiththevariousmakesandmodelsofsatisfactoryatomicabsorptionspectrometers.Theactualcon-centrationrangesmeasurablebydirectaspirationaregiveninthespecifictestmethodforeachelementofinterest.Inthemajorityofinstancestheconcentrationrangemaybeextendedlowerbyuseofelectrothermalatomizationandconverselyextendedupwardsbyusingalesssensitivewavelengthorrotatingtheburnerhead.Detectionlimitsbydirectaspirationmayalsobeextendedthroughsampleconcentration,solventextractiontechniques,orboth.Wheredirectaspirationatomicabsorptiontechniquesdonotprovideadequatesensitivity,theanalystisreferredtoPracticeD3919orspecializedproceduressuchasthegaseoushydridemethodforarsenic(TestMethodsD2972)andselenium(TestMethodsD3859),andthecoldvaportechniqueformercury(TestMethodD3223).1.3Becauseofthedifferencesamongvariousmakesandmodelsofsatisfactoryinstruments,nodetailedoperatingin-structionscanbeprovided.Insteadtheanalystshouldfollowtheinstructionsprovidedbythemanufacturerofaparticularinstrument.1.4ThevaluesstatedinSIunitsaretoberegardedasstandard.Thevaluesgiveninparenthesesaremathematicalconversiontoinch-poundunitsthatareprovidedforinforma-tiononlyandarenotconsideredstan...
