ASTM D5808-2009 374 Standard Test Method for Determining Chloride in Aromatic Hydrocarbons and Related Chemicals by Microcoulometry.pdf

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1、Designation: D 5808 09Standard Test Method forDetermining Chloride in Aromatic Hydrocarbons andRelated Chemicals by Microcoulometry1This standard is issued under the fixed designation D 5808; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r

2、evision, 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 This test method covers the organic chlorides in aro-matic hydrocarbons, their derivatives, and r

3、elated chemicals.1.2 This test method is applicable to samples with chlorideconcentrations from 1 to 25 mg/kg.1.3 This test method is preferred over Test Method D 5194for products, such as styrene, that are polymerized by thesodium biphenyl reagent.1.4 In determining the conformance of the test resu

4、lts 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 will be biased high due to partial recovery ofinorganic species during combustion. Interferenc

5、e 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 units of measurement are included in thisstandard.1.7 This standard does not purport to address

6、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 7.3 and Section 9.2. Refe

7、renced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 1555M Test Method for Calculation of Volume andWeight of Industrial Aromatic Hydrocarbons and Cyclo-hexane MetricD 3437 Practice for Sampling and Handling Liquid CyclicProductsD 5194 Test Method for Trace Chloride in Liquid

8、AromaticHydrocarbonsD 6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 691 Practice for Conducting an Interlaboratory Study toDetermine th

9、e Precision of a Test Method2.2 Other Document:OSHA Regulations, 29CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 Definitions:3.1.1 dehydration tube, nchamber containing concen-trated sulfuric acid that scrubs the effluent gases from combus-tion to remove water vapor.3.1.2 oxidative pyrolys

10、is, 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 factor, nan indication of the efficiency ofthe measurement computed by dividing the measured value ofa standard by its theoretic

11、al value.3.1.4 reference sensor pair, ndetects changes in silver ionconcentration.3.1.5 test titration, na process that allows the coulometerto set the endpoint and gain values to be used for sampleanalysis.3.1.6 titration parametersvarious instrumental conditionsthat can be changed for different ty

12、pes of analysis.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved July 1, 2009. Published July 2009. Originally approvedin 1995. Last pre

13、vious edition approved in 2003 as D 5808 - 03.2For 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.3Available from

14、 U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 working electrode (generator el

15、ectrode), nan elec-trode consisting of an anode and 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

16、 pyrolysis converts the organichalides to hydrogen 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 spe

17、cimen injected (see Annex A1).5. Significance and 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 chlori

18、de species are potentially damaging torefinery processes. 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 %.NO

19、TE 1To ensure reliable detectability, all sources of chloride con-tamination 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 bi

20、ased 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.7. Apparatus7.1 Pyrolysis Furnace, which can maintain a temperaturesufficient to pyrol

21、yze the organic matrix and convert allchlorine present 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 o

22、xygen. The inlet end of thetube must have a sample inlet 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 samp

23、le is ensured.7.3 Titration Cell, containing a reference 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

24、 the stirringbar and cause it to rise in the titration 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 amplif

25、ying the difference to theworking electrode pair to 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

26、 it enters the furnace.7.6 Controller, with connections 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 su

27、lfuric acidsolution, and water vapor is subsequently 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 Reagents

28、Reagent 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 that

29、 the reagent is of sufficiently high purity topermit 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 D 1193, Type II or III.8.3 Acetic AcidGlacial aceti

30、c acid (CH3COOH).8.4 Argon or Helium, 99.9 % minimum purity required ascarrier gas.8.5 Amidosulfonic Acid (H2NSO3H), minimum purity 99.3-100.3 %.8.6 Sodium Acetate, anhydrous, (NaCH3CO2), fine granular.8.7 Cell Electrolyte SolutionDissolve 1.35 g sodium ac-etate (NaCH3CO2) in 850 mL of acetic acid (

31、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 required as thereactant gas.8.9 Gas Regula

32、tors, 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.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Wa

33、shington, DC. For suggestions on the testing of reagents notlisted 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.D58080

34、928.13 Working Electrode Solution (10 % KNO3)Dissolve50 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)Dissol

35、ve 10.1 g potassium nitrate (KNO3) in 100 mLof distilled 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

36、 should be capable ofdissolving the chloride sample. 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,

37、4,6-Trichlorophenol to 0.1 mg. Transfer to a500-mL volumetric flask. Dilute to the mark with methanol.gCl/mL MeOH 5 grams of TCP! 3 %Cl in TCP!3 106/500 mL MeOH (1)where:TCP = 2,4,6, Trichlorophenol, andMeOH = Methanol.%Cl in TCP = 53.869. Hazards9.1 Consult the current version OSHA regulations, sup

38、pli-ers Material Safety Data Sheets, and local regulations for allmaterials used in this test method.10. Sampling10.1 Consult guidelines for taking samples from bulk inaccordance with Practice D 3437.11. Preparation of Apparatus11.1 Install the instrument in accordance with manufactur-ers instructio

39、ns.11.2 Adjust gas flows and pyrolysis temperature(s) to theoperating 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 de

40、termi-nation.12. Calibration and Standardization12.1 Using the chloride 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

41、solution and dilute to themark with solvent. (The standards are approximately 1 mgCl/mL, 15 mg Cl/mL H and 30 mg 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 either volumetri

42、-cally, by syringe, or by mass. Make sure that the sample size is80 % or less 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 vol

43、ume of liquid in the syringe. After injectingthe standard, read the volume 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 Meth

44、od D 1555M.12.4.2 Alternatively, the syringe may be weighed before andafter the injection to determine the weight of sample injected.This technique provides greater precision than the volumedelivery method, provided a balance with a precision of 60.0001 g is used.12.5 Follow the instrument manufactu

45、rers recommendationfor introducing samples into the instrument.12.6 Repeat the 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 manufactur

46、ers recommen-dations to correct.12.8 Construct a three-point curve using the 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

47、determination for the sample may require achange in titration parameters or adjustment in sample size, orboth.14. Calculation14.1 Calculate results utilizing volume and known specificgravity in milligrams per kilograms as follows:Chloride, mg/kg 5M 2 B!V 3 D31RF(2)14.2 Calculate results utilizing we

48、ight of sample, consider-ing dilutions in milligrams per kilograms as follows:Chloride, mg/kg 5M 2 B!w31RF(3)where:M = measured chloride value, g,B = blank chloride value, g,V = sample injection volume, mL,w = weight of sample, g,D = density, andRF = recovery factor =grams chlorides titratedtheoreti

49、cal value.14.3 If this equation does not apply to your instrument, thenfollow instrument manufacturers recommendations.D580809315. Report15.1 Report the chloride results as mg/kg.16. Precision and Bias516.1 PrecisionThe results from six laboratories were usedto generate statistical data. Three values were recorded for eachsample. The standard used to calibrate a standard curve wasprovided with the samples and a volume of 40 L was specifiedfor all injections. For statistical calculations, the average valueobtained on the neat (or blank) sample