1、Designation: D 5808 03Standard Test Method forDetermining Organic Chloride in Aromatic Hydrocarbonsand Related 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 c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 derivativ
3、es, and related 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 The following applies to all specified
4、 limits in thisstandard: for purposes of determining conformance with thisstandard, an observed value or a calculated value shall berounded off “to the nearest unit” in the last right-hand digitused in expressing the specification limit, in accordance withthe rounding-off method of Practice E 29.1.5
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 this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific haza
6、rdstatements, see 7.3 and Section 9.2. Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 3437 Practice for Sampling and Handling Liquid CyclicProducts3D 5194 Test Method for Trace Chloride in Liquid AromaticHydrocarbons3E 29 Practice for Using Significant Digits in Test
7、 Data toDetermine Conformance with Specifications4E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method42.2 Other Document:OSHA Regulations29CFR paragraphs 1910.1000 and1910.120053. Terminology3.1 Definitions:3.1.1 dehydration tubechamber containing concen
8、tratedsulfuric acid that scrubs the effluent gases from combustion toremove water vapor.3.1.2 oxidative pyrolysisa 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 factoran indication
9、of the efficiency of themeasurement computed by dividing the measured value of astandard by its theoretical value.3.1.4 reference sensor pairdetects changes in silver ionconcentration.3.1.5 test titrationa process that allows the coulometer toset the endpoint and gain values to be used for sample an
10、alysis.3.1.6 titration parametersvarious instrumental conditionsthat can be changed for different types of analysis.3.1.7 working electrode (generator electrode)an electrodeconsisting of an anode and a cathode separated by a salt bridge;maintains a constant silver ion concentration.4. Summary of Tes
11、t 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 halides that then flow into a titration cellwhere it reacts with silver ions present in the electroly
12、te. 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).1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals is the dir
13、ect responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved Aug. 10, 2003. Published August 2003. Originallyapproved in 1995. Last previous edition approved in 1995 as D 5808 - 95.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 06.04.4Annu
14、al Book of ASTM Standards, Vol 14.02.5Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Signific
15、ance 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 chloride species are potentially damaging toref
16、inery 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 %.NOTE 1To ensure reliable detectability, all
17、 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 biased high due to partial recovery ofinorg
18、anic 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 pyrolyze the organic matrix and convert allchl
19、orine 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 oxygen. The inlet end of thetube must have
20、 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 sample is ensured.7.3 Titration Cell, contain
21、ing 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 the stirringbar and cause it to rise in
22、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 amplifying the difference to theworking electro
23、de 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 it enters the furnace.7.6 Controller, wi
24、th 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 sulfuric acidsolution, and water vapor is s
25、ubsequently 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 a
26、ll 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.6Other grades may beused, provided that the reagent is of sufficiently high puri
27、ty 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 acetic acid (CH3COOH).8.4 Argon or Helium, 99.
28、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 (CH3COOH), anddilute to 1000 mL with water
29、 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 Regulators, two-stage gas regulators must be us
30、edfor 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)Dissolve50 g potassium nitrate (KNO3) in 500 mL of distilled water.8.14 Inner Chamber Re
31、ference 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 distilled water.8.16 Sodium Chloride (NaCl), fine granular.8.17 Sodium Perchlorate (Na
32、ClO4), crystalline.8.18 Sulfuric Acid, (sp gr 1.84), (H2SO4) concentrated.8.19 2,4,6-Trichlorophenol (TCP) (C6H3OCl3), fine granu-lar.6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the Am
33、erican 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.D58080328.20 SolventThe solvent of choice should be capable ofdissolving the chlor
34、ide 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 2,4,6-Trichlorophenol to 0.1 mg. Transfer t
35、o 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, suppli-ers Material Safety Data Sheets, and
36、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 instructions.11.2 Adjust gas flows and pyrolysis te
37、mperature(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 determi-nation.12. Calibration and Standard
38、ization12.1 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 solution and dilute to themark with solve
39、nt. (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-cally, by syringe, or by mass. Make sure
40、 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 volume of liquid in the syringe. After injec
41、tingthe 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. Several densitiesof various hydrocarbons are listed in Table 1.12.4.2 Alter
42、natively, 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 manufacturers recommendationfor
43、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 manufacturers recommen-dations to
44、 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 determination for the s
45、ample may require achange in titration parameters or adjustment in sample size, orboth.14. Calculation14.1 Measurement utilizing volume and known specificgravity in milligrams per kilograms as follows:Chloride, mg/kg 5M 2 B!V 3 D31RF(2)14.2 Measurement utilizing weight of sample, consideringdilution
46、s 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 titratedtheoretical value.14.3 If this equation does
47、not apply to your instrument, thenfollow instrument manufacturers recommendations.15. Report15.1 Report the chloride results as (mg/kg) of the sample.TABLE 1 Densities of Common HydrocarbonsAComponent Density Temperature CBenzene 0.879 20Cyclohexane 0.779 20Ethylbenzene 0.867 20Isopropylbenzene 0.86
48、2 20Toluene 0.867 20m-Xylene 0.864 20o-Xylene 0.880 20AHandbook of Chemistry and Physics, 40th Edition,“ Table, Physical Constantsof Organic Compounds,” Chemical Rubber Co.D580803316. Precision and Bias716.1 PrecisionThe results from six laboratories were usedto generate statistical data. Three valu
49、es 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 was subtracted from theaverage value for the 1 mg/kg, 5 mg/kg, and 25 mg/kg samples.16.2 Intermediate PrecisionTwo successive test resultsgenerated by the same laboratory, on the same sample, by thesame operator, with the same test equipment should not beconsidered suspect unless the difference is gr
