ASTM E2469-2008 Standard Test Method for Chloride in Monoethylene Glycol by Ion Chromatography.pdf

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1、Designation: E 2469 08Standard Test Method forChloride in Monoethylene Glycol by Ion Chromatography1This standard is issued under the fixed designation E 2469; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi

2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of inorganicchloride (chloride ion) in polyester-grade and low-conductivity-grade mon

3、oethylene glycol (MEG) in the range of0.01 to 1.0 mg/kg by ion chromatography (IC).1.2 Monoethylene glycol can be analyzed directly by thistest method without any sample preparation.1.3 The values given in SI units are to be considered as thestandard. The values given in parentheses are for informat

4、iononly.1.4 Review the current Material Safety Data Sheets (MSDS)for detailed information concerning toxicity, first-aid proce-dures and safety precautions.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of

5、 this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use. For specifichazard statements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE 180 Practice for Determining

6、the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty ChemicalsE 300 Practice for Sampling Industrial Chemicals3. Summary of Test Method3.1 An aliquot of the polyester-grade or low-conductivity-grade monoethylene glycol (MEG) sample is injected directly(manually) into an

7、 ion chromatograph consisting of an injectorwith a fixed sample loop, two anion exchange columns (guardand separator column), an anion suppressor and a conductivitydetector. Ions are separated based on their affinity for the ionexchange sites of the resin with respect to the resins affinity forthe e

8、luent. The suppressor increases the sensitivity of the testmethod by both increasing the conductivity of the analytes anddecreasing the conductivity of the eluent. The suppressorconverts the eluent and the analytes to the correspondinghydrogen form acids. The chloride is detected by conductivitydete

9、ction and identified by retention time. Quantitation is bypeak area using an external standard calibration curve. Instruc-tions are provided for two equivalent IC systems.4. Significance and Use4.1 This test method provides for the quantitative determi-nation of inorganic chloride (chloride ion) in

10、monoethyleneglycol (MEG) by direct injection using ion chromatographywith conductivity detection. The analysis time is less than 5min with no sample preparation required. Conductivity detec-tion is a universal detection mode and is linear over the rangeof the method. Acceptable levels of chloride in

11、 polyester-gradeand low-conductivity-grade MEG vary with the manufacturersspecifications but are normally in the low mg/kg range.Knowledge of the chloride content in polyester-grade andlow-conductivity-grade MEG is required to establish whetherthe product meets specification requirements.5. Interfer

12、ences5.1 The identification of chloride is based on retention time.Interferences can be caused by ionic substances with retentiontimes similar to that of chloride. If the eluent conditions arechanged or the column capacity changes, it is possible thatother anions may coelute with chloride and cause

13、an interfer-ence.5.2 Any anion that elutes after chloride under the analysisconditions used in the test method may cause an interference ifthe run time of the method isnt long enough to include thatanion. When the run time of a method is too short, a late elutinganion from one analysis may be detect

14、ed during the nextanalysis and cause an interference if it elutes at the same timeas chloride. Carbonate, if present in a sample, may cause aninterference in IC systems using hydroxide eluent (like Con-figuration B) if the run time of the analysis is not long enoughto include the carbonate peak. The

15、 elution time of carbonateunder the analysis conditions used in this test method is1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved April 1, 2008

16、. Published May 2008. Originallyapproved in 2006. Last previous edition approved in 2006 as E 2469 06.2For 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

17、Document Summary page onthe ASTM website.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.directly related to the amount of carbonate in the sample. Thehigher the conce

18、ntration of carbonate in a sample, the faster thecarbonate elutes from the column.5.3 Method interferences can be caused by the contamina-tion of glassware, eluent and reagents with chloride. Care mustbe taken to ensure glassware and apparatus are free of chloride.The use of latex gloves is recommen

19、ded to prevent chloridecontamination while handling samples and reagents.5.4 In an IC system with an electrolytic membrane basedsuppressor operated in the recycle mode, the eluent is recycledback through the suppressor after it exits the conductivity cellto provide a source of water for electrolytic

20、 generation ofhydronium ions for the regenerant. Using this system configu-ration, there is an interference caused by the glycol sample asit passes back through the suppressor. This interference appearsas a large broad peak that upsets the baseline during the timechloride elutes from the column. Acc

21、urate quantitation ofchloride is very difficult if not impossible with this interferencepresent. To avoid this interference, an external supply ofreagent water is used as the source of hydronium ions for theregenerant. In the external water mode, water flows counter-current to the eluent through the

22、 suppressor. The water can bepressurized or pumped through the suppressor to achieve therequired flow rate.5.5 No other direct interferences have been observed in theuse of this test method. If results are suspect based on theanalytical history of the product, the data should be confirmedby an alter

23、nate test method.6. Apparatus6.1 Analytical Balance, capable of weighing 200 g to thenearest 0.0001 g. (See Note 1.)6.2 Pipettes, capable of measuring from 100-L to 10-mL.(See Note 1.)NOTE 1The accuracy of balances and pipettes should be confirmed ona regular basis and documentation of the check sho

24、uld be kept.6.3 Ion Chromatograph, Configuration A (Bottled EluentSystem - Carbonate-Based) (see Note 2)Analytical instru-ment with all the required accessories including an eluentpump, temperature-controlled low volume ( 2 L) conductiv-ity cell, conductivity detector, PEEK tubing, and a PEEKinjecti

25、on valve with a fixed sample loop. An auxiliary regen-erant pump or pressurized 4-L reagent bottle is required forexternal regenerant delivery. The instrument must be suitablefor analysis according to the operating conditions given in11.1.NOTE 2The ion chromatography (Configuration A) uses a carbona

26、tebased eluent system in which the eluent is prepared by the analyst fromanalytical grade reagents or commercially available concentrated carbon-ate solutions. There is more variability in the retention time of chloridewith this type of system as a result of variations in the concentration of theelu

27、ent prepared by analysts. This is the oldest and most commonly used ICsystem.6.3.1 Anion Exchange Guard Column (for Carbonate-BasedEluent), for protection of the analytical column from stronglyretained components and organics. Better separations areobtained with the additional plates of the guard co

28、lumn.6.3.2 Anion Exchange Separator Column (for Carbonate-Based Eluent), capable of producing separation of the chlorideequivalent to or better than that shown in Fig. 1.6.3.3 Anion Suppressor, an electrolytic self-regeneratingmembrane suppressor, micromembrane suppressor or equiva-lent suppressor c

29、apable of lowering the background conduc-tance of the eluant to a level that allows the method detectionlimit to be achieved.6.3.4 Chromatography Data System, for data acquisitionand data processing.6.4 Ion Chromatograph, Configuration B (Eluent Genera-tion System - Hydroxide Eluent) (see Note 3)Ana

30、lyticalinstrument with all the required accessories including an eluentpump, temperature controlled low volume ( 2 L) conductiv-ity cell, conductivity detector, PEEK tubing, PEEK injectionFIG. 1 Representative Sample Chromatogram Obtained Using the Conditions Outlined in 11.1 (Configuration A)E24690

31、82valve with a fixed sample loop and electrolytic eluent genera-tion module. An auxiliary regenerant pump or pressurized 4-Lreagent bottle is required for external regenerant delivery. Theinstrument must be suitable for analysis according to theoperating conditions given in 11.2.NOTE 3The IC system

32、(Configuration B) uses on-line electrolyticeluent generation to produce a hydroxide eluent. The hydroxide eluent isgenerated from reagent water using an eluent generator cartridge. Theconcentration of hydroxide eluent is very reproducible, so the retentiontime for chloride is less variable than with

33、 a carbonate eluent. This newertechnology for eluent generation eliminates the variability of eluentpreparation by an analyst. It also eliminates the problems with eluentaging (weakening) and contamination.NOTE 4The IC system in Configuration B uses on-line electrolyticeluent generation to produce t

34、he eluent. The type of eluent produceddepends on the eluent generator cartridge used with the IC system. Thereare four types of eluent generator cartridges including potassium hydrox-ide, carbonate-bicarbonate, lithium hydroxide and sodium hydroxide. Forthis test method the potassium hydroxide eluen

35、t cartridge is recommendedfor use with hydroxide selective columns. The carbonate-bicarbonateeluent cartridge and eluent pH modifier can be used with carbonateselective columns (6.3.1 and 6.3.2) if the analyst prefers on-linecarbonate-bicarbonate eluent generation.6.4.1 Anion Exchange Guard Column (

36、for Hydroxide Elu-ent), for protection of the analytical column from stronglyretained components and organics. Better separations areobtained with the additional plates of the guard column.6.4.2 Anion Exchange Separator Column (for HydroxideEluent), capable of producing separation of chloride equiva

37、lentto or better than that shown in Fig. 2.6.4.3 Anion Exchange Trap Column (for Hydroxide Eluent),electrolytic continuously regenerated trap column or equivalenttrap column capable of removing anionic impurities fromreagent water used with the eluent generation cartridge.6.4.4 Anion Suppressor, an

38、electrolytic self-regeneratingmembrane suppressor, micromembrane suppressor or equiva-lent suppressor capable of lowering the background conduc-tance of the eluant to a level that allows the method detectionlimit to be achieved.6.4.5 Eluent Generator Cartridge, capable of producingcarbonate-free pot

39、assium hydroxide.36.4.6 Chromatography Data System, for data acquisitionand data processing.6.4.7 Chromatography Operating System, capable of con-trolling the current required for eluent generation and trapcolumn regeneration.6.5 Volumetric Glassware, 100-mL, 1-L, and 2-Lvolumetricflask. (See Note 5

40、.)6.6 Plastic Cups with Lids, 120 mL. (See Note 5.)6.7 Weigh Dish, small disposable polystyrene. (See Note 5.)6.8 Bottles with Caps, 125-mL Nalgene low density poly-ethylene (LDPE) narrow mouth. (See Note 5.)3The sole source of supply of the potassium hydroxide eluent generationcartridge known to th

41、e committee at this time is Dionex Corp., 1228 Titan Way,Sunnyvale CA94088-3603. If you are aware of alternative suppliers, please providethis information to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou

42、 may attend.FIG. 2 Representative Sample Chromatogram Obtained Using the Conditions Outlined in 11.2 (Configuration B)E24690836.9 Plastic Syringe, 10-mL with Luer-Lok Tip. (See Note5.)NOTE 5Care should be taken to ensure glassware, reagents andapparatus are free of chloride contamination.7. Reagents

43、 and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society (ACS)where such specifications are available.4Other

44、 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 High-Purity WaterUnless otherwise indicated, refer-ences to water shall be understood to mean reagent water asdefined by Type I

45、I of Specification D 1193. It is recommendedthat all water be filtered through a 0.2-m filter. For eluentpreparation, it is recommended to degas the water by spargingwith helium or vacuum degassing and sonication.7.3 Sodium Chloride, ACS reagent grade.7.4 Chloride Quality Assurance Check Standard, a

46、n inde-pendent, certified 10 g/mL chloride standard (not made fromsodium chloride in 7.3), may be purchased commercially.7.5 Sodium Carbonate (Configuration A), ACS reagentgrade.7.6 Sodium Bicarbonate (Configuration A), ACS reagentgrade.7.7 Sodium Carbonate Concentrate (Configuration A), 0.5M sodium

47、 carbonate, commercially available.7.8 Sodium Bicarbonate Concentrate (Configuration A), 0.5M sodium bicarbonate, commercially available.7.9 Monoethylene Glycol (MEG) (High Purity), with lowconcentrations of impurities.NOTE 6 Impurities in high-purity MEG used for preparation of thechloride working

48、standards or for sample dilution should not exceed 0.01mg/kg. This information should be provided by the supplier or determinedby the analyst before use.7.10 Sulfuric Acid (for use with anion micromembranesuppressor), concentrated sulfuric acid (95 to 98 %).7.11 Anion Regenerant Concentrate (for use

49、 with anionmicromembrane suppressor), 1 M sulfuric acid, commerciallyavailable.7.12 Isopropyl Alcohol (2-Propanol), ACS reagent grade.7.13 Methyl Alcohol (Methanol, alternate for IsopropylAlcohol), ACS reagent grade.7.14 Monoethylene Glycol Quality Control Sample, polyes-ter grade MEG.8. Reagent Solutions8.1 Chloride Stock Solution (1000 mg/kg Chloride in Wa-ter):NOTE 7As an alternative, a 1000 g/mL chloride standard may bepurchased commercially.NOTE 8The density of the commercial chloride stock solution isassumed to be 1.0 g/mL at room temperature for wt/wt calc