ASTM_D_4795_-_94_2008.pdf

Designation:D479594(Reapproved 2008)Standard Test Method forNitrogen Content of Soluble NitrocelluloseAlternativeMethod1This standard is issued under the fixed designation D4795;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.1.Scope1.1 Test Methods D301 for measuring nitrogen content innitrocellulose by nitrometer are the accepted standard.However,the glassware is specialized and the precision isdependent on the development of a high level of skill by theoperator.The ferrous-sulfate titration of nitrate is a classicalprocedure.By controlling critical variables and automating theactual titration,precision equivalent to the nitrometer can beachieved with nitrocellulose.This test method describes such aprocedure.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For specific hazardstatements,see Section 8.2.Referenced Documents2.1 ASTM Standards:2D301 Test Methods for Soluble Cellulose Nitrate(With-drawn 2011)3D1193 Specification for Reagent Water3.Summary of Test Method3.1 A weighed specimen of nitrocellulose is dissolved insulfuric acid and titrated automatically with ferrous sulfate.The nitrogen content of the specimen is calculated using theequivalence factor of the ferrous sulfate.4.Significance and Use4.1 This test method provides a simpler means for measur-ing the nitrogen content of nitrocellulose than the nitrometerdescribed in Test Methods D301.Under controlled conditions,the procedure described is capable of results equivalent tothose obtained by the nitrometer.5.Interferences5.1 The presence of moisture(or other volatile components)in the specimen will affect results.It is recommended that onlythoroughly dry specimens be used.5.2 Temperature rise must be controlled during the titration.The cooling bath provides that control.However,if the rate oftitrant addition is too fast,temperature may rise out of control.Results may then be erratic.Adherence to the procedure willavoid temperature excursions.For optimum system efficiency,room temperature should be maintained at 23 6 2C.5.3 The strength of the sulfuric acid used to dissolve thespecimen is very important.Too low an acid strength slows therate of solution which,in turn,causes titrations to be abnor-mally slow.Results then become erratic.6.Apparatus6.1 Acid Bottle Safety Dispenser.6.2 Brinkman 20 Titration System,or equivalent,with 25mL amber buret:6.2.1 Electrode,platinum.6.2.2 Electrode,glass.6.3 Desiccator,with drying agent.6.4 Weighing bottles,12-mL capacity,aluminum(preferred)or glass.6.5 Analytical Balance,accurate to 60.1 mg.6.6 Ovens135C,for drying standards,and 100C,fordrying specimens,having unexposed heating elements and thedoor latch removed.6.7 Circulating Unit,for chilled water,5 6 2C.6.8 Blender,with 0.25-L(8-oz)blender jar.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1,2008.Published June 2008.Originallyapproved in 1988.Last previous edition approved in 2003 as D4795 94(2003).DOI:10.1520/D4795-94R08.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type III of Specification D1193.7.3 Sulfuric Acid(H2SO4)95 to 98%.7.4 Ferrous Sulfate SolutionDissolve 350 g of ferroussulfate crystals(FeSO4)in 1000 mL of distilled water.Add1000 mL of 1+1 H2SO4solution.Makes 2 L.7.5 Potassium Nitrate(KNO3)Standard or an eq