ASTM D5808-2018 9375 Standard Test Method for Determining Chloride in Aromatic Hydrocarbons and Related Chemicals by Microcoulometry.pdf

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1、Designation: D5808 18Standard Test Method forDetermining Chloride in Aromatic Hydrocarbons andRelated Chemicals by Microcoulometry1This standard is issued under the fixed designation D5808; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev

2、ision, 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. Scope*1.1 This test method covers the organic chlorides in aro-matic hydrocarbons, their derivatives, and re

3、lated chemicals.1.2 This test method is applicable to samples with chlorideconcentrations from 0.7 mg/kg limit of quantitation (LOQ) to25 mg/kg. The limit of detection (LOD) is 0.2 mg/kg based onPTP data.1.3 This test method is preferred over Test Method D5194for products, such as styrene, that are

4、polymerized by thesodium biphenyl reagent.1.4 In determining the conformance of the test results usingthis method to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E29.1.5 Organic chloride values of samples containing inorganicchlorides w

5、ill be biased high due to partial recovery ofinorganic species during combustion. Interference from inor-ganic species can be reduced by water washing the samplebefore analysis. This does not apply to water soluble samples.1.6 The values stated in SI units are to be regarded asstandard. No other uni

6、ts of measurement are included in thisstandard.1.7 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, health, and environmental practices and deter-mine the appli

7、cability of regulatory limitations prior to use.For specific hazard statements, see 7.3 and Section 9.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of Internatio

8、nal Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1555M Test Method for Calculation of Volume and Weightof Industrial Aromatic Hydrocarbons and

9、CyclohexaneMetricD3437 Practice for Sampling and Handling Liquid CyclicProductsD5194 Test Method for Trace Chloride in Liquid AromaticHydrocarbonsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits

10、in Test Data toDetermine Conformance with SpecificationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 Definitions:3.1.1 dehydration tube, nchamber contain

11、ing concen-trated sulfuric acid that scrubs the effluent gases from combus-tion to remove water vapor.3.1.2 oxidative pyrolysis, na process in which a sample iscombusted in an oxygen-rich atmosphere at high temperatureto break down the components of the sample into elementaloxides.3.1.3 recovery fac

12、tor, nan indication of the efficiency ofthe measurement computed by dividing the measured value ofa standard by its theoretical value.3.1.4 reference sensor pair, ndetects changes in silver ionconcentration.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic, Industrial, Spe

13、cialty and Related Chemicals is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved June 1, 2018. Published August 2018. Originallyapproved in 1995. Last previous edition approved in 2014 as D5808 09a (2014).DOI: 10.1520/D5808-18.2For referenced ASTM sta

14、ndards, 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.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Ca

15、pitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in

16、 accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.5 test titration, na p

17、rocess that allows the coulometerto set the endpoint and gain values to be used for sampleanalysis.3.1.6 titration parameters, nvarious instrumental condi-tions that can be changed for different types of analysis.3.1.7 working electrode (generator electrode), nan elec-trode consisting of an anode an

18、d a cathode separated by a saltbridge; maintains a constant silver ion concentration.4. Summary of Test Method4.1 A liquid specimen is injected into a combustion tubemaintained at 900C having a flowing stream of oxygen andargon carrier gas. Oxidative pyrolysis converts the organichalides to hydrogen

19、 halides that then flow into a titration cellwhere it reacts with silver ions present in the electrolyte. Thesilver ion thus consumed is coulometrically replaced and thetotal electrical work to replace it is a measure of the organichalides in the specimen injected (see Annex A1).5. Significance and

20、Use5.1 Organic as well as inorganic chlorine compounds canprove harmful to equipment and reactions in processes involv-ing hydrocarbons.5.2 Maximum chloride levels are often specified for processstreams and for hydrocarbon products.5.3 Organic chloride species are potentially damaging torefinery pro

21、cesses. Hydrochloric acid can be produced inhydrotreating or reforming reactors and this acid accumulatesin condensing regions of the refinery.6. Interferences6.1 Both nitrogen and sulfur interfere at concentrationsgreater than approximately 0.1 %.NOTE 1To ensure reliable detectability, all sources

22、of chloridecontamination must be eliminated.6.2 Bromides and iodides, if present, will be calculated aschlorides. However, fluorides are not detected by this testmethod.6.3 Organic chloride values of samples containing inorganicchlorides will be biased high due to partial recovery ofinorganic specie

23、s during combustion. Interference from inor-ganic species can be reduced by water washing the samplebefore analysis. This does not apply to water soluble samples.7. Apparatus7.1 Pyrolysis Furnace, which can maintain a temperaturesufficient to pyrolyze the organic matrix and convert allchlorine prese

24、nt in the sample to hydrogen chloride.7.2 Pyrolysis Tube, made of quartz and constructed so thatwhen a sample is volatilized in the front of the furnace, it isswept into the pyrolysis zone by an inert gas, where itcombusts when in the presence of oxygen. The inlet end of thetube must have a sample i

25、nlet port with a septum throughwhich the sample can be injected by syringe. The inlet endmust also have side arms for the introduction of oxygen andinert carrier gas. The pyrolysis tube must be of ample volume,so that complete pyrolysis of the sample is ensured.7.3 Titration Cell, containing a refer

26、ence and sensor pair ofelectrodes and a generator anode/cathode pair of electrodes tomaintain constant chloride ion concentration. An inlet from thepyrolysis tube and magnetic stirring is also required.(WarningExcessive stirring speed will decouple the stirringbar and cause it to rise in the titrati

27、on cell and possibly damagethe electrodes. A slight vortex in the cell will be adequate.)7.4 Microcoulometer, capable of measuring the potential ofthe sensing-reference electrode pair, and comparing this poten-tial with a bias potential, and amplifying the difference to theworking electrode pair to

28、generate a current. The microcou-lometer output voltage signal should be proportional to thegenerating current.7.5 Automatic Boat Drive, having variable stops, such thatthe sample boat may be driven into the furnace, and stopped atvarious points as it enters the furnace.7.6 Controller, with connecti

29、ons for the reference, working,and sensor electrodes. The controller is used for setting ofoperating parameters and integration of data.7.7 Dehydration Tube, positioned at the end of the pyrolysistube so that effluent gases are bubbled through a sulfuric acidsolution, and water vapor is subsequently

30、 trapped, while allother gases are allowed to flow into the titration cell.7.8 Gas-Tight Sampling Syringe, having a 50 l capacity,capable of accurately delivering 10 to 40 l of sample.7.9 Quartz Boats.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. U

31、nless 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 that the reagent is of sufficiently high purity topermit

32、 its use without lessening the accuracy of the determi-nation.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D1193, Type II or III.8.3 Acetic AcidGlacial acetic acid (CH3COOH).8.4 Argon or Helium, 99.9 % minimum

33、purity required ascarrier gas.8.5 Amidosulfonic Acid (H2NSO3H), minimum purity 99.3-100.3 %.8.6 Sodium Acetate, anhydrous, (NaCH3CO2), fine granular.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notl

34、isted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.D5808 1828.7 Cell Electrolyte SolutionDissolve 1.35 g sodium ac-eta

35、te (NaCH3CO2) in 850 mL of acetic acid (CH3COOH), anddilute to 1000 mL with water or follow manufacturersrecommendations.NOTE 2Bulk quantities of the electrolyte should be stored in a darkbottle or in a dark place and be prepared fresh at least every two weeks.8.8 Oxygen, 99.6 % minimum purity is re

36、quired as thereactant gas.8.9 Gas Regulators, two-stage gas regulators must be usedfor the reactant and carrier gas.8.10 Potassium Nitrate (KNO3), fine granular.8.11 Potassium Chloride (KCl), fine granular.8.12 Potassium Sulfate (K2SO4), crystalline.8.13 Working Electrode Solution (10 % KNO3)Dissolv

37、e50 g potassium nitrate (KNO3) in 500 mL of distilled water.8.14 Inner Chamber Reference Electrode Solution (1 MKCl)Dissolve 7.46 g potassium chloride (KCl) in 100 mL ofdistilled water.8.15 Outer Chamber Reference Electrode Solution (1 MKNO3)Dissolve 10.1 g potassium nitrate (KNO3) in 100 mLof disti

38、lled water.8.16 Sodium Chloride (NaCl), fine granular.8.17 Sodium Perchlorate (NaClO4), crystalline.8.18 Sulfuric Acid, (sp gr 1.84), (H2SO4) concentrated.8.19 2,4,6-Trichlorophenol (TCP) (C6H3OCl3), fine granu-lar.8.20 SolventThe solvent of choice should be capable ofdissolving the chloride sample.

39、 The solvent of choice shouldhave a boiling point similar to the sample being analyzed.Suggested possibilities include, but not limited to, methanol,isooctane, toluene, and p-xylene.8.21 Chloride Standard Stock SolutionWeigh accurately0.093 g of 2,4,6-Trichlorophenol to 0.1 mg. Transfer to a500-mL v

40、olumetric flask. Dilute to the mark with methanol.gCl/mL MeOH 5 grams of TCP! 3 %Cl in TCP!3106/500 mL MeOH (1)where:TCP = 2,4,6, TrichlorophenolMeOH = Methanol%Cl in TCP = 53.869. Hazards9.1 Consult the current version OSHA regulations, suppli-ers Safety Data Sheets, and local regulations for all m

41、aterialsused in this test method.10. Sampling10.1 Consult guidelines for taking samples from bulk inaccordance with Practice D3437.11. Preparation of Apparatus11.1 Install the instrument in accordance with manufactur-ers instructions.11.2 Adjust gas flows and pyrolysis temperature(s) to theoperating

42、 conditions as recommended by the manufacturer.11.3 The actual operation of injecting a sample will varydepending upon the instrument manufacturer and the type ofinlet system used.11.4 Prebake the sample boats to be used for the determi-nation.12. Calibration and Standardization12.1 Using the chlori

43、de standard stock solution (see 8.21),make a series of three calibration standards covering the rangeof expected chloride concentration.12.2 Into three 100-mL volumetric flasks, respectively pipet1, 15, and 30 mL of chloride stock solution and dilute to themark with solvent. (The standards are appro

44、ximately 1 gCl/mL, 15 g Cl/mL H and 30 g Cl/mL.)12.3 It is customary to use a one-point calibration, but ifanalyzing a wide range of samples, use a three-point calibra-tion.12.4 The sample size can be determined eithervolumetrically, by syringe, or by mass. Make sure that thesample size is 80 % or l

45、ess of the syringe capacity.12.4.1 Volumetric measurement can be utilized by filling thesyringe with standard, carefully eliminating all bubbles, andpushing the plunger to a calibrated mark on the syringe, andrecording the volume of liquid in the syringe. After injectingthe standard, read the volume

46、 remaining in the syringe. Thedifference between the two volume readings is the volume ofstandard injected. This test method requires the known ormeasured density, to the third decimal place. Densities can befound in Test Method D1555M.12.4.2 Alternatively, the syringe may be weighed before andafter

47、 the injection to determine the weight of sample injected.This technique provides greater precision than the volumedelivery method, provided a balance with a precision of60.0001 g is used.12.5 Follow the instrument manufacturers recommendationfor introducing samples into the instrument.12.6 Repeat t

48、he measurement of each calibration standard atleast three times.12.7 If the calibration standards come out high or low,prepare fresh standards. If the calibration standards remainhigh or low, follow the instrument manufacturers recommen-dations to correct.12.8 Construct a three-point curve using the

49、 instrumentmanufacturers recommendations.13. Procedure13.1 Clean the syringe to be used for the sample. Flush itseveral times with the sample. Determine the chloride concen-tration in accordance with 12.4 12.6.13.2 Chloride determination for the sample may require achange in titration parameters or adjustment in sample size, orboth.D5808 18314. Calculation14.1 Calculate results utilizing volume and known specificgravity in milligrams per kilograms as follows:Chloride, mg/kg 5M 2 B!V 3D31RF(2)14.2 Calculate results utilizing weight of sample,