1、Designation:D495489(Reapproved 2009)Standard Test Method forDetermination of Nitrilotriacetates in Detergents1This standard is issued under the fixed designation D4954;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、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 This test method describes the determination of nitrilo-triacetates(NTA)in detergents.1.2 The values stated in SI units are to b
3、e regarded asstandard.No other units of measurement are included in thisstandard.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 deter
4、mine the applica-bility of regulatory limitations prior to use.For specific safetyprecautions,see 6.5.2.Summary of Test Method2.1 A known excess amount of copper nitrate solution isadded to the detergent sample under controlled pH conditions.The uncomplexed copper is back-titrated potentiometrically
5、with a standard NTA solution using a copper ion specificelectrode.The millimoles of NTA in the sample are equivalentto the millimoles of copper added,less the millimoles of theNTA titrant.3.Significance and Use3.1 This test method is suitable in research,development,and manufacturing control to moni
6、tor the level of NTA,asequestering agent,in powder and liquid detergents.3.2 Accurate determination of a sequestering agent is im-portant in evaluating cost and performance of detergent prod-ucts.4.Interferences4.1 The presence of substances that will make coppercomplex like citrate,formate,ethylene
7、diaminetetraacetate,andphosphonate,will interfere positively in the determination ofNTA.5.Apparatus5.1 Volumetric Flasks,200-mL,500-mL,1000-mL.5.2 Beakers,200-mL(tall form),250-mL,1000-mL.5.3 Pipets,25-mL,100-mL.5.4 Graduated Cylinders,10-mL,25-mL.5.5 Copper Ion Electrode(Orion Model 94-29).5.6 Sing
8、le Junction Reference Electrode(Orion Model 90-01),filled with Orion 90-00-01 solution.5.7 pH Combination Electrode.5.8 Burets,10-mL,25-mL,50-mL.5.9 pH Meter,with millivolt capabilities.5.10 Automatic Titratormay be substituted for 5.8 and5.9.5.11 Magnetic Stirrer/Hot Plate.5.12 Balance,with 1-mg se
9、nsitivity.6.Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to specifications of the Committeeon Analytical Reagents of the American Chemical Society,where such specifications are available.2Othe
10、r grades may besubstituted,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Disodium Ethylenediaminetetraacetate(EDTA),0.1 M.36.3 Nitric Acid,concentrated.6.4 Sodium Hydroxide,50%reagent solution.
11、6.5 Sodium Hydroxide,20%solution.Mix 40 g of the 50%solution with 60 g of water.Cool.Wear a face shield duringmixing.6.6 Cupric Nitrate,0.1 M.Weigh(to the nearest 0.1 g)6.3g of copper metal and transfer into a 600-mLbeaker.Add about100 mL of water.Place a magnetic bar into the beaker and1This test m
12、ethod is under the jurisdiction of ASTM Committee D12 on Soapsand Other Detergents and is the direct responsibility of Subcommittee D12.12 onAnalysis and Specifications of Soaps,Synthetics,Detergents and their Components.Current edition approved Oct.1,2009.Published December 2009.Originallyapproved
13、in 1989.Last previous edition approved in 2003 as D4954-89(2003).DOI:10.1520/D4954-89R09.2American Chemical Society,1155 16th St.,NW,Washington,DC 20036.3EDTA solution is available from J.T.Baker Inc.,already standardized againstNIST Reference Material Calcium Carbonate.Copyright ASTM International,
14、100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 place on a stirrer/hotplate.Add 30 mL of concentrated nitricacid while stirring and heat gently.Stir until the copper metaldissolves.Add more nitric acid if undissolved metal remains.After dissolution,cool and transfer
15、quantitatively to a 1-Lvolumetric flask.Dilute to the mark and mix the solution well.6.6.1 Alternatively,weigh out(to the nearest 1 g)23 g ofreagent grade cupric nitrate,212hydrate crystals,and transferto a 600-mL beaker.Add 400 mL of water.Stir to dissolve thecrystals and add 5 mL of concentrated n
16、itric acid.Transfer toa 1-L volumetric flask,dilute to the mark and mix well.6.7 Trisodium Nitrilotriacetate Monohydrate(NTA),0.3 M.Weigh out(to the nearest 1 g)41 g of NTA and dissolve in 400mL of water in a 600-mL beaker.Transfer to a 500-mLvolumetric flask,dilute to the mark and mix well.6.8 Sodium Acetate Buffer Solution,Dissolve 68 g of re-agent sodium acetate,trihydrate,in 500 mL of water in a 1-Lbeaker.Add 30 g of glacial acetic acid.Transfer to a 1-Lvolumetric flask,dilute with water to