ASTM_E_1371_-_90_1999.pdf

Designation:E 1371 90(Reapproved 1999)Standard Test Method forGravimetric Determination of Phosphorus in Phosphorus-Copper Alloys or Phosphorus-Copper-Silver Alloys1This standard is issued under the fixed designation E 1371;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the gravimetric determinationof phosphorus in phosphorus-copper or phosphorus-copper-silver alloys containing 1 to 15%phosphorus.1.2 This standard does not purport to address the safetyconcerns,if any,associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2.Referenced Documents2.1 ASTM Standards:E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2E 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals3E 255 Practice for Sampling Copper and Copper Alloys forDetermination of Chemical Composition33.Summary of Test Method3.1 After dissolution of the sample in nitric acid,phospho-rus is precipitated with ammoniacal magnesium chloride.Magnesium ammonium phosphate is separated by filtration andredissolved with dilute hydrochloric acid.Phosphorus is repre-cipitated with ammoniacal magnesium chloride,then filtered,ignited,and weighed as magnesium pyrophosphate.4.Significance and Use4.1 This test method for the chemical analysis of metals andalloys is primarily intended to test such materials for compli-ance with compositional specifications.It is assumed that allwho use this method will be trained analysts capable ofperforming common laboratory procedures skillfully andsafely.It is expected that the work will be performed in aproperly equipped laboratory.5.Interferences5.1 Silver is complexed as diamminesilver(I).Copper iscomplexed as tetraminecopper(II).5.2 When present,tin interferes by forming insoluble stan-nic phosphate.Other elements which form insoluble phos-phates or hydroxides in ammoniacal solution also interfere.6.Apparatus and Reagents6.1 Magnesium Chloride PrecipitantDissolve 65 g ofmagnesium chloride(MgCl2)and 140 g of ammonium chloride(NH4Cl)in 500 mL water,add 375 mL of NH4OH,dilute to 1L with water,and mix.6.2 Potassium Chlorate SolutionDissolve 10 g of potas-sium chlorate(KClO3)in 200 mL water.7.Sampling7.1 Select the sample so as to be representative of thematerial to be analyzed.7.2 For procedures for sampling the material,refer toPractice E 255.8.Procedure8.1 Select and weigh a sample in accordance with thefollowing:Phosphorus,%Sample Weight,gTolerance in SampleWeight,mg0.25 to 2.02.00.42.0 to 10.01.00.310.0 to 15.00.50.28.2 Place the weighed sample in a 400-mL beaker.Add 20mL of HNO3(1+1).Heat to dissolve the sample and boil toexpel the oxides of nitrogen.Add 10 mL of potassium chloratesolution to complete the oxidation of the phosphorus tophosphate.Continue boiling and evaporate to between 5 and 10mL then cool.If crystals appear,add a few millilitres of waterto dissolve them.A faint cloudiness in the solution mayindicate the presence of silver chloride.8.3 Dilute to 125 mL and heat to boiling.Remove from heatand carefully add 25 mL of magnesium chloride precipitantfollowed by 50 mL of NH4OH.Stir with a glass rod,leavingthe rod in the beaker.Cool overnight to allow for completeprecipitation.1This test method is under the jurisdiction of ASTM Committee E-1 onAnalytical Chemistry for Metals,Ores,and Related Materials and is the directresponsibility of Subcommittee E01.03 on Precious Metals.Current edition approved July 27,1990.Published September 1990.2Annual Book of ASTM Standards,Vol 14.02.3Annual Book of ASTM Standards,Vol 03.05.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.8.4 Set up a vacuum filter using a glass funnel and 12.5-cmlow porosity,ashless filter paper4with a 9-cm hardened ashlessfilter paper as a support.5Moisten these with water and packwith enough filter pulp to fill the funnel about34in.from thebottom.Transfer the solution and precipitate to the funnel andrinse the beaker three times with NH4OH(1+19).Some of theprecipitate may stick to the beaker and stirring rod.It is notnecessary to remove it completely,because the beaker will beused for the second precipitation.Wash the filter paper andprecipitate four times with 10-mLportions of NH4OH(1+19).8.5 Turn off the vacuum,set the funnel aside,empty thefilter flask,and discard the filtrate and washings containing thecopper and silver.Rinse the filter flask three times with waterand reinsert the funnel containing the precipitate.8.6 Turn the vacuum on and dissolve the magnesiumammonium phosphate precipitate through the filter