ASTM_D_515_-_88.pdf

Designation:D 515 88Standard Test Methods forPhosphorus in Water1This standard is issued under the fixed designation D 515;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope*1.1 These test methods cover the determination of phospho-rus in water and wastewater.The following two methods areincluded:SectionsMethod AColorimetric Ascorbic Acid Reduction8 to 16Method BSemiautomated Digestion/Colorimetric Ascorbic AcidReduction17 to 251.2 This standard may involve hazardous materials,opera-tions,and equipment.This standard does not purport toaddress all of the safety problems associated with its use.It isthe responsibility of the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.For aspecific caution statement,see 19.1.1.3 Former Test Methods B(Colorimetric Amino Reduc-tion)and C(Colorimetric Molybdovanadophosphate)havebeen discontinued.Refer to Appendix X1 for historical infor-mation.2.Referenced Documents2.1 ASTM Standards:D 1066 Practice for Sampling Steam2D 1129 Terminology Relating to Water2D 1192 Specification for Equipment for Sampling Waterand Steam in Closed Conduits2D 1193 Specification for Reagent Water2D 2777 Practice for Determination of Precision and Bias ofMethods of Committee D-19 on Water2D 3370 Practices for Sampling Water from Closed Con-duits2E 60 Practice for Photometric and SpectrophotometricMethods for Chemical Analysis of Metals3E 275 Practice for Describing and Measuring Performanceof Ultraviolet,Visible,and Near Infrared Spectrophotom-eters43.Terminology3.1 Definitions For definitions of terms used in these testmethods,refer to Terminology D 1129D 1129.4.Summary of Test Methods4.1 Both test methods are based on reactions that arespecific for the orthophosphate ion.With Test Method A theanalytical scheme shown in Fig.1 is used to measure variousforms of phosphorus in the water sample.The separations intovarious forms are largely analytically defined,but the differ-entiations have been selected for interpretive purposes.4.1.1 Separation into dissolved and total recoverable formsdepends on filtration of the water sample through a 0.45-mmembrane filter.A reproducible,gross separation of dissolvedfrom particulate forms of phosphorus is made with the uniformpore size membrane filter,but no claim can be made thatseparation is complete.The sample should be filtered as soonas possible after it is drawn if dissolved forms are to bemeasured,since the ratio of dissolved to particulate phosphorusmay change when analysis is delayed.Total recoverablephosphorus includes all phosphorus forms when the unfiltered,shaken sample is heated in the presence of sulfuric acid andammonium persulfate.4.1.2 Orthophosphate(A)Only orthophosphate and a neg-ligible amount of hydrolyzable phosphorus is measured whenthe test is run on the undigested sample.An insignificantfraction of the hydrolyzable phosphorus may be converted toorthophosphate on addition of the acidic reagent during thetest,particularly if completion of the test is delayed after theaddition of acid.1These test methods are under the jurisdiction of ASTM Committee D-19 onWater and are the direct responsibility of Subcommittee D 19.05 on InorganicConstituents in Water.Current edition approved Aug.19,1988.Published March 1989.Originallypublished as D 515 38 T.Last previous edition D 515 82.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 03.05.4Annual Book of ASTM Standards,Vol 03.06.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.4.1.3 Hydrolyzable Phosphorus+Orthophosphate(B)By boiling the sample in the presence of acid such hydrolyz-able phosphorus materials as meta-,pyro-,and tripolyphos-phates are converted to orthophosphate.The measurement willinclude these forms of phosphorus plus the orthophosphatepresent in the unboiled sample and a reaction of a few organicphosphorus forms.4.1.4 Total Phosphorus(C)The acid-persulfate digestionof the sample converts all forms of phosphorus includingorganic forms to orthophosphate,and hence measures all formsexcept possibly certain heavy metallic phosphates present insediments.4.1.5 The following calculations can be made for specificphosphorus forms:Organic phosphorus 5 C 2 BHydrolyzable phosphorus 5 B 2 AParticulate phosphorus 5 total recoverable phosphorus!2total dissolved phosphorus!4.2 Selection of the test method to use for a specific waterdepends primarily on its expected phosphorus content.Allphosphorus forms are measured with the Colorimetr