ASTM_D_1339_-_84_scan.pdf

ASTM D133984075951000215004Designation:D 1339-840-2675Standard Test Methods forSULFITE ION IN WATER1This standard is issued under the fixed designation D1339;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.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.These methods have been approved for use by agencies of the Department of Defense and for listing in the DoD Index of Specificationsand Standards.1.Scope3.Definitions1.1 These test methods cover the volumetric3.1 For definitions of terms used in thesedetermination of sulfite ion in water.The follow-methods refer to Definitions D 1129.ing three methods are included:Range4.Significance and UseSectionMethod A0.1 to 6 mg/L7to144.1 The determination of sulfite is usuallyNa2SO3made on process waters,boiler waters,and otherMethod B6 mg/L Na2SO315to22waters that have been treated with sodium sulfite.or higherGenerally,in boiler applications,a catalyzed so-Method C3 mg/L Na2SO323to29or higherlution of sodium sulfite is injected continuouslyinto the feedwater system for the purpose of1.2 Method B may be used for samples con-removing dissolved oxygen to prevent pitting andtaining less than 6 mg/L Na2SO3 with some lossexcessive oxidation of metal components.Inof precision;in such applications the end pointmost boiler operations,the sulfite concentrationmay be determined with starch indicator.is maintained above 20 mg/L in the boiler water.1.3 This standard may involye hazardous ma-Sulfite injection is restricted to lower-pressureterials,operations,and equipment.This standardboilers(1000 psi,6900 kPa)because of thedoes not purport to address all of the safety prob-tendency for decomposition at higher tempera-lems associated with its use.It is the responsibil-tures.When exposed to the environment,dis-ity of whoever uses this standard to consult andcharges containing sulfites will react with theestablish appropriate safety and health practicesoxygen to form sulfates.Generally speaking,sul-and determine the applicability ofregulatory limi-fites are not found in natural waters.tations prior to use.5.Purity of Reagents5.1 Purity of Reagents-Reagent grade chem-2.Applicable Documentsicals shall be used in all tests.Unless otherwise2.1 ASTM Standards:indicated,it is intended that all reagents shallD 1129 Definitions of Terms Relating toconform to the specifications of the CommitteeWater2on Analytical Reagents of the American Chemi-D 1192 Specification for Equipment for Sam-pling Water and Steam2D 1193 Specification for Reagent Water2These test methods are under the jurisdiction of ASTMCommittee D-19 on Water and are the direct responsibility ofD2777 Practice for Determination of Preci-Subcommittee D19.05 on Inorganic Constituents in Water.sion and Bias of Methods of CommitteeCurrent edition approved Jan.27,1984.Published MarchD-19 on Water21984.Originally published as D1339-54 T.Last previousedition D 1339-78.D 3370 Practices for Sampling Water22 Annual Book of ASTM Standards,Vol 11.01.665ASTM D1339 84075951000215014D1339cal Society,where such specifications are avail-10.Apparatusable.3 Other grades may be used,provided it is10.1 Sample Tubes-The glass sample tubes,4first ascertained that the reagent is of sufficientlyas shown in Fig.1,have a nominal capacity ofhigh purity to permit its use without lessening500 mL.The capacity of each tube shall bethe accuracy of the determination.determined to the nearest 1 mL.5.2 Purity of Water-Unless otherwise indi-10.2 Burets-The four 10-mL burets shallcated,references to water shall be understood tohave stopcock bores not greater than 2 mm andmean reagent water conforming to Specificationmaximum tip diameters not exceeding 3 mm.D1193,Type II.10.3 Stirrer-The motor-driven stirrer shall6.Samplingbe variable-speed and equipped with a glass pro-peller.6.1 Collect the sample in accordance with10.4 Dead-Stop Electrometric Titrator-ThePractices D3370.electrometric dead-stop indicating apparatus6.2 For Method C,add 10 mL of EDTA so-shall be equipped with platinum electrodes.Thelution to the 1-L sampling bottle before takingassembly shall be sensitive to the addition of 0.05the sample.Fill the bottle to the brim,cap,andmL of 0.005 N sodium thiosulfate(Na2S2O3)shake well to mix.The EDTAsolution com-solution to 500 mL of water.plexes such ions as cobalt and copper,whichcatalyze the rapid oxidation of sulfite when the11.Reagentssample is exposed to the air.11.1 Hydrochloric Acid(1+1)-Mix 1 volumeNorE 1-To avoid premature oxidation of sulfite,of concentrated hydrochloric acid(HCl,sp grthe titration should be carried out immediately after1.19)with 1 volume of water.collection.11.2 Potassium Dichromate-Heat potas-sium dichromate(K2Cr2Oz)in a platinum cru-METHOD Acible to a temperature just above its fusion point(396C),taking care to exclude all dust and or-7.Scopeganic matter.After cooling,erush the fused salt7.1 This test method is applicable to the de-to a powder in an agate mortar and preserve intermination of sulfite ion in water,especiallya glass-stoppered bottle.boiler water and boiler feedwater,in which the11.3 Potassium Iodate Solution,Standardsulfite ion concentration is 0.1 to 6 mg/L.:(0.025 N)-Dissolve xg of potassium iodate7.2 The analyst should be aware that adequate(KIO3),dried at 120C,and 0.5 g of sodiumcollaborative data for precision and bias state-bicarbonate(NaHCO3)in water and dilute to 1ments.as required by Practice D 2777 is notL(x=8.92 times the normality of the standardprovided.See Precision and Bias section for de-Na2S2O3 solution,see 11.6).tails11.4 Potassium Iodide-The potassium io-dide(KI)shall not impart a blue color when 1 g8.Summary of Methodis dissolved in 20 mL of freshly boiled water8.1 The sample is taken in a tube of special3Reagent Chemicals,American Chemical Society Specifi-design to exclude air until the sulfite has beencations,Am.Chemical Soc.,Washington,D.C.For suggestionsreacted with iodine chloride.The excess iodineon the testing of reagents not listed by the American ChemicalSociety,seeReagent Chemicals and Standards,by Josephchloride is determined by titration with thiosul-Rosin,D.Van Nostrand Co.,Inc.,New York,N.Y.,and thefate.The range of the method is limited byUnited States Pharmacopeia.reagent concentrations.4McLean-type sampling tube,as modified by the MarineEngineering Laboratory,U.S.Navy,and by the Heat ExchangeInstitute.This tube is the same as that specified in.ASTM9.InterferencesMethods D888,Referee Methods B and C for Dissolved Oxygenin Water,Annual Book ofA.STM Standards,Part 31.9.1 Other reducing agents such as sulfides and3 Ulmer,R.C.,Reynar,J.M.,and Decker,J.M.,Applica-bility of Schwartz-Gurney Method for Determining Dissolvedcertain heavy-metal ions react like sulfite withOxygen in Boiler Feedwater,and Modification of the Methodiodine chloride and cause high results.Nitrite,ifto Make it Especially Applicable in the Presence of Such Im-present,will oxidize sulfite when the sample ispurities as are Encountered in Power Plants,Proceedings,Am.Soc.Testing Mats.,Vol 43,1943,pp.1261-63.acidified.6Reagent used for standardization purposes only.666ASTMD133984075951000215024D1339treated with 5 drops of 1 N sulfuric acid(H2SO4)lution prepared in this manner will remain chem-and 1 mL of freshly prepared starch solution.ically stable for 1 year.11.5 Potassium Iodide Solution(50 g/L)-NorE 2-If the indicator is not prepared as specifiedDissolve 50 g of iodate-free KI and 0.5 g ofor a proprietary starch indicator preparation is used thesodium bicarbonate(NaHCO3)in freshly boiledreport of analysis shall spell out the deviation.and cooled water and dilute to 1 L.11.6 Sodium Thiosulfate Solution,Standard12.Procedure(0.10 N)-Using a 1000-mL volumetric flask,12.1 Sampling-Arrange the sample tube indissolve 24.82 g of sodium thiosulfate(Na2S2O3.a support so that it is vertical,with its upper5H2O)in approximately 800 mL of water thatoutlet free of hose connections and at a levelhas just been boiled and cooled,by inverting thehigher than the valve for adjustment of sampleflask at regular short intervals.Stabilize the so-flow.Connect the lower end to the sampling linelution by dissolving in it,in the same manner,1by means of rubber tubing.The sampling lineg of sodium carbonate(Na2COa),and make upshall contain a suitable cooling coil if the waterto 1 L with boiled water.Standardize againstbeing sampled is above temperature,in whichK2Cr207,as follows:case the sample shall be cooled to ambient-air11.6.1 Dissolve 2 g of iodate-free KI and 2 gtemperature.If a cooling coil is used,the valveof NaHCO3 in 300 mL of water in a 500-mLfor cooling-water adjustment shall be at the inletErlenmeyer flask and add HCI(sp gr 1.19)slowly,to the cooling coil,and the overflow shall be towhile swirling the flask,until carbon dioxide a point oflower elevation.The valve for adjusting(CO2)gas evolution ceases.Add 10 mL excess of the flow of sample shall be at the outlet from theHCI,mix,and then dissolve 0.098 g of driedcooling coil.Adjust the sample to a rate that willK2Cr2O7(see 11.2).Wash down the inside of thefill the tube in 40 to 60 s and continue this flowflask with a small amount of water without agi-long enough to provide at least ten changes oftating the flask,and allow to stand for 10 min.water in the sampling tube.If the sampling line11.6.2 Titrate with the Na2S2O3 solution,us-is used intermittently,allow a suitably longering starch solution as the indicator,until the colortime for the first sample to ensure adequatejust changes from blue to the green color of theflushing of the sampling line and cooling coil.chromic salt.Close the upper stopcock of the tube,and im-11.6.3 Calculate the normality of the Na2S2O3mediately close the lower stopcock and removesolution,as follows:the tubing connection.If the line being sampledis under such high pressure that the samplingN=(A/49.94B)1000tubes or connecting tubing may burst with thewhere:water hammer when the stopcocks are closed,N=normality of the Na2S203 solution,throttle the sample flow with the control valve4 grams of K2Cr207 used,andjust before the sample is removed,but do notB millilitres of Na2S2O3 solution required forshut off the sample flow completely.the titration.12.2 Fixing-Fill the three burets with HCI11.7 Sodium Thiosulfate Solution,Standard(1+1),KI solution,and 0.025 N KIO3 solution,(0.005 N-Transfer 25 mL of the nominallyrespectively.Flick the water from the upper nip-0.10 NNa2S203 solution to a 500-mL volumetricple of the sample tube and fill the nipple to theflask.Dilute to the mark with water and mixupper calibration mark with HCI.If a bubble iscompletely.This solution shall be prepared notentrapped in the nipple within or below themore than 12 to 15 h before using.reagent,remove it by probing with a clean plati-11.8 Starch Indicator-Make a paste of 6g of num wire until the bubble rises to the surface.arrowroot starch or soluble iodometric starchOpen the lower stopcock and admit the reagentwith cold water.Pour the paste into 1 L of boilingby control with the upper stopcock until thewater.Then add 20 g of potassium hydroxidemeniscus in the nipple coincides with the lower(KOH),mix thoroughly,and allow to stand forcalibration mark.If the sample contains more2 h.Add 6 mL of glacial acetic acid(99.5%)than 800 mg/L of NaOH,add 2 mL more ofMix thoroughly and then add sufficient HCl(spacid for each 1000 mg/L of alkalinity or fractiongr 1.19)to adjust the pH value of the solution tothereof in excess of 800 mg/L.Close both stop-4.0.Store in a glass-stoppered bottle.Starch so-cocks and rinse both nipples with a fine stream667ASTM D1339 6407595100021503T.D1339of water.Mix the contents by shaking or rotation,14.Precision and Bias?and flick out the excess water from each nipple.14.1 The precision of this method may beInvert the tube and fill what is now the upperexpressed as follows:nipple with KI solution to the 2-mL calibrationmark,Introduce the solution into the sample,S=0.2repeating the stopcock control,the rinsing ofwhere:both nipples,the shaking and rotating,and theS=overall precision expressed in mg/L offlicking of water from the nipples.Again invertNa2SO3.the tube and now introduce 2.0 mL of 0.025 N14.2 The supporting data on this collaborativeKIO3 solution into the sample following the di-study do not include information on the numberrections given above for adding the reagents andof participating laboratories,water used,or sin-rinsing the nipples.Once more,shake and rotategle-operator precision or bias.It is the responsi-the tube to mix the sample thoroughly.bility of the analyst to assure the validity of the12.3 Titration of Sample-Invert the sample.method in a particular water.tube and drain the sample into a clean 800-mLMETHOD BGiffin low-form beaker by opening both stop-cocks.Do not rinse or blow into the sampling15.Scopetube,but shake the last drops from the nipple15.1 This method covers the determination ofinto the beaker.Add several drops of starchsulfite ion in water,especially boiler water andindicator to indicate the approach of the endboiler feedwater,in which the sulfite concentra-point.Insert the electrodes of the electrometriction is 6 mg/L or higher.dead-stop indicating apparatus into the sample,15.2 The analyst shoeld be aware that ade-start the stirrer at low speed,and titrate the excessquate collaborative data for precision and bias asiodine chloride with 0.005 N Na2S2O3 solution.required by Practice D 2777 is not provided.See12.4 Determination of Blank(Note 3)-MakePrecision and Bias section for details.a blank titration of 500 mL of water containingno sulfite;to which have been added the three 16.Summary of Methodreagents that were added to the sample in 12.2.16.1 Provision is made for excluding air fromNorE 3-Alternatively,if such tubes are available,the sample while it is being taken.Potassiumone sample of 500 mL and one sample of 250 mL areiodate is then added to form iodine chloride withcollected simultaneously,fixed as described in 12.2,potassium iodide and hydrochloric acid to oxi-and titrated as described in 12.3.The difference in thedize the sulfite ion.The excess iodine chloride isnet amounts of 0.025 N KIO3 solution used by thesulfite content of the two samples will be the sulfite-iontitrated with sodium thiosulfate solution,usingequivalent of a 250-mL sample.an electrometric indicator to show the end point.17.Interferences13.Calculation17.1 High results may be caused by the pres-13.1 Calculate the concentrations of sulfite asence of other reducing materials such as sulfidemilligrams per L of sodium sulfite(Na2SO3),asand ferrous iron.Nitrite,if present,will oxidizefollows:sulfite when the sample is acidified.Sulfite as Na2SO3,mg/L=63000N(A-B)/S18.Apparatuswhere:18.1 Erlenmeyer Flask,wide-mouth,500-mL,N=normality of the Na2S2O3 solution,fitted with inlet,outlet,and siphon-leveling con-4 millilitres of Na2S203 solution needed tonections,as shown in Fig.2.titrate the blank,18.2 Magnetic Stirring Apparatus,with swing-B=millilitres of Na2S2O3 solution needed toing support if electrometric end point-indicatingtitrate the sample,andapparatus is used.S=sampling-tube volume in millilitres minus18.3 Dead-Stop End Point-Indicating Appa-613.2 To convert mg/L of Na2SO3 to mg/LSupporting data for these methods have been filed at ASTMof sulfite ion,multiply by 0.635.Headquarters as RR:D19-155.668ASTM D1339840759510002150414D1339ratus-See 10.4.This apparatus is not necessary21.Calculationfor less precise testing(see 1.2).21.1 Calculate the concentration of sulfite asmilligrams per litre of sodium sulfite(Na2SO3),19.Reagentsas follows:19.1 Hydrochloric acid(1+1)-See 11.1.Sulfite as Na2So3,mg/L 126 N(A-B)19.2 Potassium Iodate Solution,Standardwhere:(0.05 N)-Dissolve x g of potassium iodateN normality of the NazS2O3 solution,(KIO3),dried at 120C and 0.5 g of sodium4 millilitres of NazS2O3 solution needed tobicarbonate(NaHCO3)in water and dilute totitrate the blank,and500 mL,in a volumetric flask,(x=8.92 timesB millilitres of Na2S203 solution required tothe normality of the standard Na2S2O3 solution,titrate the sample.see19.5).21.2 To convert milligrams per litre of Na2SO319.3 Potassium Todide(50 g/L)-See 11.5.to milligrams per litre of sulfite ion,multiply by19.4 Sodium Thiosulfate Solution,Standard0.635.(0.10W-See11.6.19.5 Sodium Thiosulfate Solution,Standard22.Precision and Bias?(0.01 N-Transfer 50 mL of the 0.10 N sodium22.1 The single-operator,single-laboratorythiosulfate(Na2S203)solution to a 500-mL vol-precision(SLo)of this method at a level of 10.3umetric flask.Dilute to the mark with water andmg/L Na2SO3 may be expressed as follows:mix completely.This solution should be pre-SLo=0.12 mg/Lpared not more than 12 to 15 h before using.19.6 Starch Indicator-See 11.8.22.2 The supporting data on this study do notinclude waters used or bias.It is the responsibilityof the analyst to assure the validity of the method20.Procedurein a particular water.20.1 Connect the sampling flask to the sampleMETHOD Ccooler with rubber tubing so that the sample,ator slightly below room temperature,enters the23.Scopebottom of the flask and overflows from the top.23.1 This test method is particularly applica-Overflow an estimated volume of five times theble for control tests where good precision is notflask volume,allowing the siphon to fill duringrequired and the sulfite content is 3 mg/L orthis step.Then close off the inlet connection andhigher.open the syphon to adjust the sample volume to23.2 The analyst should be aware that ade-500mL.quate collaborative data for precision and bias20.2 Fixing-Remove the stopper from thestatements as required by Practice D 2777 is notflask,set the flask on the magnetic stirrer plat-provided.See Precision and Bias section for de-form,and operate the stirrer at low speed whiletails.5 mL of HCl,5 mL of KI solution,and 5.0 mLof KIO3 solution are added immediately and in24.Summary of Methodthat order.If the sample contains more than 30024.1 Iodine,liberated by potassium iodate so-mg/L of sulfite,use correspondingly largerlution,reacts with the sulfite in the water sample.amounts of reagents.An end point is reached when excess iodine is20.3 Titration-Add several drops of starchpresent,as shown by the blue color producedindicator solution to indicate the approach of thewith starch indicator.end point.Insert the electrodes of the end pointindicator into the sample and titrate the excess25.Interferencesiodine chloride with 0.01 N Na2S2O3 solution.25.1 EDTA is added to the sample to complex20.4 Determination of Blank-Make a blanksuch metallic ions as copper that catalyze thetitration of 500 mL of water containing no sulfiteoxidation of sulfite when the sample is exposedto which have been added in the same way andto air.Other reducing agents such as sulfides andin the same volume the reagents used to fix theferrous iron will cause high results since theysample(see 20.2).react like sulfite.Sulfamic acid is added to react669