1、Designation: D 1157 91 (Reapproved 2004)An American National StandardStandard Test Method forTotal Inhibitor Content (TBC) of Light Hydrocarbons1,2This standard is issued under the fixed designation D 1157; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case 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 determination of totalp-tertiary-butylcatechol inhibi
3、tor added to polymerization andrecycle grades of butadiene or to other C4hydrocarbonmixtures containing no phenolic material other than catechol orno oxidized phenolic material other than that derived fromoxidation of catechol. In general, all phenols and their quinoneoxidation products are included
4、 in the calculated catecholcontent. Small amounts of polymer do not interfere. This testmethod is applicable over the range of TBC from 50 to 500mg/kg.1.2 The values stated in SI units are to be regarded asstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, asso
5、ciated 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.2. Referenced Documents2.1 ASTM Standards:3D 1265 Practice for Sampling Liquified Petroleum (LP)Gase
6、s (Manual Method)3. Summary of Test Method3.1 The catechol is separated from the butadiene by evapo-ration. The residue is dissolved in water and an excess of ferricchloride is added. The intensity of the yellow-colored complexis compared in a photoelectric colorimeter with that producedby known con
7、centrations of the catechol.4. Significance and Use4.1 p-tertiary-butylcatechol is commonly added to commer-cial butadiene in amounts of 50 to 250 mg/kg as an oxidationinhibitor. This test method is suitable for use by both producersand users of butadiene within the limitations described inSection 1
8、.5. Apparatus5.1 PhotometerA sensitive photoelectric photometer ca-pable of producing light of narrow spectral range that ispredominantly blue (425 nm).5.2 Graduates, 100-mL.5.3 Volumetric Flasks, 100-mL; or stoppered graduatedmixing cylinder, 100-mL.5.4 Erlenmeyer Flasks, 250-mL.5.5 Funnels, 75-mm
9、diameter.5.6 Pipet, 5-mL.6. Reagents6.1 Purity of ReagentsReagent 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 specificat
10、ions are available.4Other 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.6.2 Purity of WaterReferences to water shall be under-stood to mean distilled water.6.3 Ferric Chloride, S
11、tandard Solution Dissolve 20.0 g offerric chloride (FeCl36H2O) in ethanol (95 %). Add 9.2 mL ofHCl (sp gr 1.19), and then dilute with ethanol (95 %) to 1000mL in a volumetric flask.6.4 p-Tertiary-Butylcatechol, Standard(WarningPotentially hazardous. May cause skin irritation or burns; canbe absorbed
12、 through the skin. May be harmful or fatal if1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.D0 on Hydrocarbons for Chemical and Special Uses.Current edition approved Nov. 1, 2004. Published Nov
13、ember 2004. Originallyapproved in 1951. Last previous edition approved in 2000 as D 1157 91 (2000)e1.2This test method was derived from the method developed and cooperativelytested by the Butadiene Producers Committee on Specifications and Methods ofAnalysis of the Office of Rubber Reserve, which ap
14、pears in the ButadieneLaboratory Manual as Method 2.1.9.1.3For 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.4Re
15、agent Chemicals, American Chemical 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 Pharmacopeiaa
16、nd National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.swallowed. Avoid contact with eyes; may burn and impairvision. May be harmful to respiratory system. May
17、producequinones and flammable butylenes on decomposition. Use withadequate ventilation. Store in flammable liquids storage area.)Dissolve 0.63 g of p-tertiary-butylcatechol (95 % minimumpurity) in 10 mLof ethanol (95 %) and dilute with water to 100mL in a volumetric flask. When used in place of 100
18、mL (63 g)of sample, consider 1.00 mLof this solution to be equivalent to100 ppm of catechol. This solution is not stable and should beprepared as needed.7. Sampling7.1 Supply samples to the laboratory in high-pressuresample cylinders. Use the procedures described in PracticeD 1265 or similar methods
19、.8. Calibration and Standardization8.1 Preparation of Standard SolutionsPrepare a standard-ization curve showing the relation between the absorbance andthe catechol content as follows: Make up solutions of knowncatechol content by pipetting 0, 1, 2, 3, 4, and 5-mLportions ofthe standard catechol sol
20、ution (1.00 mL = 100 mg/kg) intoseparate 100-mL volumetric flasks, or stoppered, graduatedmixing cylinders. Then add enough water to each flask orcylinder to make a total volume of approximately 90 mL. Add5.0 6 0.1 mL of standard FeCl3solution, bring the totalvolume to 100 mL and mix well.8.2 Measur
21、ement of StandardsFive to fifteen minutesafter the addition of the FeCl3reagent, measure the absorbanceof the solution by means of a photoelectric photometer, usingwater as a reference standard and using light that is predomi-nantly blue (425 nm).8.3 Preparation of Calibration CurveSubtract the read
22、ingobtained for the zero catechol standard from each of the abovereadings, using the same volumes of FeCl3solution and waterand observing the same time limits. Record the difference asthe respective“ net” absorbance. Assuming 1.0 mL of thestandard catechol solution to be equal to 100 mg/kg of catech
23、olin the butadiene, plot the net absorbance against the amount ofadded catechol in mg/kg.NOTE 1While this test method of plotting a curve is the recognizedmethod, it has been found that the blank or zero reading using the FeCl3reagent described in 6.3 does not change, thus enabling, for control work
24、,the plotting of a curve that can be read directly.9. Procedure9.1 Preparation of SampleMeasure 100 6 1 mL of liquidsample (WarningExtremely flammable gas under pressure.May form explosive peroxides upon exposure to air. Harmful ifinhaled. Irritating to eyes, skin, and mucous membranes.) intoa gradu
25、ate that has been cooled to below 20C. Pour thesample into a 250-mL Erlenmeyer flask and allow the liquid toevaporate at room temperature behind a shield in a well-ventilated hood. A steam bath may be used to complete theevaporation. Add 30 mL of water to the flask, stopper, shake,and filter through
26、 a rapid, hardened, low-ash paper that haspreviously been moistened. Repeat with two more 30-mLportions of water. Combine all filtrates, add from a pipet 5.0 60.1 mL of standard FeCl3solution, dilute to 100 mL, and mixwell.9.2 Measurement of SampleAfter the addition of theFeCl3reagent, allow the sol
27、ution to stand for from 5 to 15 min,then measure the absorbance of the solution by means of aphotoelectric photometer, using water as a reference standard.NOTE 2Take care to have the comparison tubes clean and free fromfingerprints and spilled solution. From time to time, the two tubes shouldbe chec
28、ked against each other with blank solution in both.9.3 Measurement of SampleMake a “blank” determina-tion, following the same procedure, but omitting the addition ofthe sample. Subtract the absorbance of the “blank” from that ofthe sample and record the difference as the “net” absorbance.NOTE 3A “bl
29、ank” determination need be made only when first usinga bottle of freshly prepared FeCl3solution to ascertain that the reagent wasmade properly.10. Calculation10.1 By use of the calibration curve, convert the netabsorbance obtained to milligrams per kilograms of p-tertiary-butylcatechol.11. Precision
30、 and Bias11.1 PrecisionThe precision of this test method as ob-tained by statistical examination of interlaboratory test resultsis as follows:11.2 RepeatabilityThe difference between successive testresults obtained by the same operator with the same apparatusunder constant operating conditions on id
31、entical test materialwould, in the long run, in the normal and correct operation ofthe test method exceed the following values only one case intwenty:p-tertiary butylcatecholrange, mg/kg Repeatability50 to 500 1011.3 ReproducibilityThe difference between two singleand independent results obtained by
32、 different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod exceed the following values only one case in twenty:p-tertiary butylcatecholrange, mg/kg Reproducibility50 to 500 2011.4 BiasSince there is
33、no accepted reference materialsuitable for determining the bias for the procedure in this testmethod for measuring TBC in hydrocarbons, no statement onbias is being made.12. Keywords12.1 light hydrocarbons; oxidation inhibitor; p-tertiary bu-tylcatechol; photometerD 1157 91 (2004)2ASTM International
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37、t the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 1157 91 (2004)3
