1、Designation: D4367 02 (Reapproved 2012)Standard Test Method forBenzene in Hydrocarbon Solvents by Gas Chromatography1This standard is issued under the fixed designation D4367; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 determination by gaschromatography of benzene at levels from 0.01 to 1 volume %in hy
3、drocarbon solvents.NOTE 1For benzene levels lower than 0.01 volume %, use TestMethod D6229.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 For purposes of determining conformance of an ob-served or a calculated value us
4、ing this test method to relevantspecifications, test result(s) shall be rounded off “to the nearestunit” in the last right-hand digit used in expressing thespecification limit, in accordance with the rounding-off methodof Practice E29.1.4 This standard does not purport to address all of thesafety co
5、ncerns, 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.1.5 For hazard information and guidance, see the suppliersMaterial Safety Data S
6、heet. For specific hazard statements, seeSection 7.2. Referenced Documents2.1 ASTM Standards:2D6229 Test Method for Trace Benzene in HydrocarbonSolvents by Capillary Gas ChromatographyE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE300 Practice for
7、Sampling Industrial Chemicals3. Summary of Test Method3.1 An internal standard, methyl ethyl ketone (MEK), isadded to the material and then introduced into a gas chromato-graph equipped with two columns connected in series. Thespecimen passes first through a column packed with thenonpolar phase, met
8、hyl silicone, which separates the compo-nents by boiling point. After octane has eluted, the flowthrough the nonpolar column is reversed, flushing out thecomponents heavier than octane. The octane and lightercomponents then pass through a column with the highly polarphase, 1,2,3-tris(2-cyanoethoxy)p
9、ropane, that separates thearomatic and nonaromatic compounds. The eluted componentsare detected by a conventional detector and recorded on a stripchart. The peak areas are measured and the concentration ofeach component is calculated by reference to the internalstandard.4. Significance and Use4.1 Be
10、nzene is classed as a toxic and carcinogenic material.A knowledge of the concentration of this compound may be anaid in evaluating the possible health hazards to personshandling and using hydrocarbon solvents, but this test methodis not intended to evaluate such hazards.5. Apparatus5.1 Chromatograph
11、Any gas chromatographic instrumentthat has a backflush system and flame ionization detector andthat can be operated at the conditions given in Table 1. Thedetector-recorder combination must produce a 4-mm deflectionfor a 1-L specimen containing 0.05 volume % MEK whenoperated at maximum sensitivity.5
12、.2 Columns, one 0.8-m (2.5-ft) length of 3.2-mm (18-in.)outside diameter stainless steel tubing and one 4.6-m (15-ft)length of 3.2-mm (18-in.) outsider diameter stainless steeltubing.5.3 Recorder, Strip ChartPotentiometer with a full-scaledeflection of 1 mV, a full-scale response time of2sorless, an
13、da maximum noise level of 60.3 % of full scale.5.4 Microsyringe, 5-L capacity.5.5 Pipets, measuring 1 and 2 mL, graduated in 0.01 mL; 5,10, and 20-mL capacity.5.6 Flasks, volumetric, 25 and 100-mL capacity.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings
14、, Materials, and Applications and is the direct responsibility ofSubcommittee D01.35 on Solvents, Plasticizers, and Chemical Intermediates.Current edition approved July 1, 2012. Published September 2012. Originallyapproved in 1984. Last previous edition approved in 2007 as D4367 02 (2007).DOI: 10.15
15、20/D4367-02R12.2For 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.*A Summary of Changes section appears at the e
16、nd of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.7 Vibrator, electric.5.8 Vacuum Source.5.9 Evaporator, vacuum, rotary.5.10 Flask, boiling, round-bottom, short-neck, with 24/40 Tjoint, 500-mL capacity. Suitable for
17、 use with the evaporator(see 5.9).5.11 Lamp, infrared.5.12 Burets, automatic, with integral reservoir, 25-mL ca-pacity.NOTE 2Suppliers of stationary phases and supports can be found inResearch Report RR:D01-1038, available from ASTM InternationalHeadquarters.6. Reagents and Materials6.1 Purity of Re
18、agentsReagent 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.3Other grades may beused, provide
19、d it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Acetone.6.3 Chloroform.6.4 Diatomaceous Earth4Acid-washed, 60 to 80 meshand 80 to 100 mesh.6.5 Helium, 99.99 % pure.6.6 Methanol.6.7 Methylene Chloride.6.
20、8 Methyl Ethyl Ketone (MEK), 99.9 mol %.6.9 Methyl Silicone.46.10 1,2,3-Tris(2-Cyanoethoxy) Propane (TCEP).46.11 Calibration Standards.6.11.1 Benzene, 99+mol %.6.11.2 Isooctane, 99+mol %.6.11.3 n-Nonane, 99+mol %.7. Hazards7.1 Many hydrocarbon solvents are flammable and hazard-ous; use special preca
21、utions when handling them. Of thereagents used in this procedure, methanol, chloroform, meth-ylene chloride, acetone, methyl ethyl ketone, benzene (see 4.1),and n-nonane are hazardous.7.2 Benzene is volatile and highly flammable. Exercise careto prevent accidental ignition. Benzene is also carcinoge
22、nicand toxic; acute or chronic poisoning may result from inhala-tion of benzene vapor, absorption of benzene through the skin,or drinking benzene.8. Sampling8.1 Take samples of solvents to be analyzed by this testmethod using the procedures described in Practice E300.9. Preparation of Columns9.1 Col
23、umn Packing PreparationPrepare the two packingmaterials, one containing 10 % methyl silicone and the other25 % TCEP, as follows:9.1.1 Weigh 45 g of the acid-washed calcined diatomitesupport 60 to 80 mesh, into a 500-mL flask (see 5.10). Dissolve5 g of the methyl silicone in approximately 50 mL ofchl
24、oroform. (WarningChloroform is a toxic material andinhalation must be avoided.) Pour the methyl siliconechloro-form solution into the flask containing the support. Attach theflask to the evaporator (see 5.9), connect the vacuum, and startthe motor. Turn on the infrared lamp and allow the packing tom
25、ix thoroughly until dry.9.1.2 Weigh 75 g of acid-washed pink diatomaceous earth,80 to 100 mesh, into a 500-mL flask (see 5.10). Dissolve 25 gof TCEP in 200 mL of methanol and pour into the flaskcontaining the support. Attach the flask to the evaporator (see5.9), connect the vacuum, and start the mot
26、or. Turn on theinfrared lamp and allow the packing to mix thoroughly untildry, but do not heat the packing above 180C.9.2 Column Preparation:9.2.1 Clean the stainless steel tubing as follows: Attach ametal funnel to one end of the steel tubing. Hold or mount thestainless steel tubing in an upright p
27、osition and place a beakerunder the outlet end of the tubing. Pour about 50 mL ofmethylene chloride into the funnel and allow it to drain throughthe steel tubing into the beaker. Repeat the washing with 50 mLof acetone. Remove the funnel and connect the steel tubing to3Reagent Chemicals, American Ch
28、emical Society Specifications, AmericanChemical Society, Washington, 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.
29、Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4See Note 2.TABLE 1 Instrument Conditions Found Satisfactory forMeasuring Low Concentrations of Benzene inHydrocarbon Solvents (Note 2)Detector flame ionizationColumns two, stainless steelLength, m (A) 0.8; (B) 4.6Outside diameter, mm 3.2Stationary
30、 phases (A) methyl silicone, 10 weight %(B) TCEP, 25 weight %Support (A) acid-washed calcined diatomite, 60 to80-mesh(B) acid-washed pink diatomaceousearth, 80 to 100-meshReference column any column or restriction may be usedTemperature, CInjection port 150Column, isothermal 100Detector block 150Car
31、rier gas heliumFlow rate, mL/min approximately 30Recorder range, mV 0 to 1Chart speed, mm/min 10Specimen size, L 1.0Time to backflush, min approximately 2Total cycle time, min approximately 30D4367 02 (2012)2an air line, by means of vinyl tubing. Remove all solvent fromthe steel tubing by blowing fi
32、ltered, oil-free air through orapplying a vacuum.9.2.2 Pack the 0.8-m (2.5-ft) tubing (Column A) with themethyl silicone packing (see 9.1.1) and the 4.6-m (15-ft) tubing(Column B) with the TCEP packing (see 9.1.2) as follows:Preform Columns A and B separately to fit the chromato-graphic instrument.
33、Close one end of each tubing with a small,glass wool plug and connect this end to a vacuum source bymeans of a glass-wool packed tube. To the other end connect asmall polyethylene funnel by means of a short length of vinyltubing. Start the vacuum and pour the appropriate packing intothe funnel until
34、 the column is full. While filling each column,vibrate the column with the electric vibrator to settle thepacking. Remove the funnel and shut off the vacuum source.Remove the top 6 mm (14 in.) of packing and insert a glasswool plug in this end of the column.9.3 Prepacked columns conforming to specif
35、ications listedin Table 1, and in 5.2, 9.1, and 9.2 may be obtained from anyreputable chromatography supply company.10. Preparation of Chromatographic Apparatus andEstablishment of Conditions10.1 Column ConditioningJoin Columns A and B asshown in Fig. 1. Connect the inlet of Column A to the injectio
36、nport of the chromatograph. Pass helium gas through the columnat approximately 40 mL/min. Condition the columns in accor-dance with the following time-temperature schedule.Temperature, C Time, h501210012150 1170 310.2 Connect the outlet of Column B to the detector port.Adjust the operating condition
37、s to those listed in Table 1, butdo not turn on the detector circuits. Check the system for leaks.10.3 Adjust the flow rate as follows:10.3.1 Set the value in the forward flow mode (Fig. 2(a)and adjust Flow Controller A to give the required flow rate(Table 1). Measure the flow rate at the detector v
38、ent, specimenside.10.3.2 Set the valve in the backflush position (Fig. 2(b) andmeasure the flow rate at the detector vent, specimen side. If therate has changed, adjust Flow Controller B to obtain therequired flow rate to within 61 mL/min.10.3.3 Turn on the detector circuit. Change the valve fromfor
39、ward flow to the backflush position several times andobserve the baseline. There should be no baseline shift or driftafter the initial peak resulting from the pressure surge with thevalve change. If there is a baseline shift, slightly increase ordecrease flow with Controller B to balance the baselin
40、e. (Apersistent drift indicates leaks somewhere in the system.)10.4 Determine time before backflushing, which varies foreach column system and must be determined experimentally asfollows:10.4.1 Prepare a mixture of 5 volume % isooctane inn-nonane. Using the injection technique described in 11.3 andw
41、ith the system in the forward flow mode, inject 1 L of theisooctanen-nonane mixture. Allow the chromatogram to rununtil the n-nonane has eluted and the recorder pen has returnedto baseline. Measure the time in seconds from the injectionuntil the recorder pen returns to baseline between the isooctane
42、and n-nonane peaks. At this point all of the isooctane butessentially none of the n-nonane should have eluted. One halfof the measured time approximates the time to backflush andshould be from 30 to 120 s.10.4.2 Repeat the run, including the injection, but switchingthe system to the backflush mode a
43、t the determined backflushFIG. 1 Tubing Assembly and Instrumentation FIG. 2 Flow Switching SystemD4367 02 (2012)3time. This should result in a chromatogram of isooctane withlittle or no n-nonane evident.10.4.3 If necessary, make additional runs, adjusting the timeto backflush until a chromatogram of
44、 all the isooctane and littleor none of the n-nonane is obtained. This established backflushtime, including the actual valve operations, must be used in allsubsequent calibrations and analyses.11. Calibration and Standardization11.1 Standard SolutionsPrepare seven standard solutionscovering the rang
45、e of 0 to 1 volume % benzene as follows: Foreach standard, measure the volume of benzene listed belowinto a 100-mL volumetric flask. Dilute to volume withisooctane, with all components and glassware at normal roomtemperature, and mix thoroughly.BenzeneVolume % mL110.5 0.50.25 0.250.10 0.100.05 0.050
46、.01 0.010.005 0.00511.2 Calibration SolutionsAccurately measure 0.5 mL ofMEK into a 100-mL volumetric flask, fill to the mark with thefirst standard solution (see 11.1), and mix thoroughly. Repeatwith each of the other standard solutions.11.3 Chromatographic AnalysisUsing the conditions es-tablished
47、 in 10.3 and 10.4, chromatograph each of the calibra-tion solutions after injecting them as follows: Flush the 5-Lmicrosyringe at least three times with the calibration solutionand then fill with about 3 L, avoiding inclusion of air bubblesin the syringe. Slowly eject the material until 1.0 L remain
48、s inthe syringe. Wipe the needle with a tissue and draw back theplunger to admit 1 L of air into the syringe. Insert the needleof the syringe into the septum cap of the chromatograph andpush through the septum until the barrel of the syringe isresting against the septum cap; then rapidly push the pl
49、unger tothe hilt and immediately withdraw the needle from the injec-tion port.NOTE 3This injection technique is necessary to obtain sharp sym-metrical peaks.11.4 CalibrationMeasure the areas of the benzene and ofMEK peaks by conventional means (Note 4). Calculate theratio of the benzene peak area to the MEK peak area. Plot theconcentration of benzene versus the ratio as in Fig. 3. Thecalibration must be done to ensure that the entire chromato-graphic system is operating properly and that the concentrationof any one component has not exceeded the
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