1、Designation: D4864 90 (Reapproved 2013)Standard Test Method forDetermination of Traces of Methanol in PropyleneConcentrates by Gas Chromatography1This standard is issued under the fixed designation D4864; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, 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 determination of methanolin propylene concentrates in th
3、e range of approximately 4 to 40mg/kg (parts-per-million by weight).1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.NOTE 1There is no direct acceptable SI equivalent for screw threads.1.3 This standard does not purport to addre
4、ss 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. Specific warningstatements are given in 11.1.1, 11.2.1, a
5、nd 12.11.2. Referenced Documents2.1 ASTM Standards:2D4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsE260 Practice for Packed Column Gas Chromatography3. Terminology3.1 Definitions:3.1.1 propylene concentrateconcentrate containing morethan 90 % propylene.3.2 Definitions
6、of Terms Specific to This Standard:3.2.1 outage tubea length of 6.35-mm (14 in.) outsidediameter SS tubing normally attached to the inside end of avalve used on a pressure sampling cylinder. It is used tofacilitate removal of a set quantity of liquified sample toprevent overpressuring the cylinder.4
7、. Summary of Test Method4.1 A known weight of water is pressured into a samplecylinder containing a known amount of liquified propylene.The contents in the cylinder are shaken and the water/methanolphase is withdrawn. A reproducible volume of the extract isthen injected into a gas chromatograph (GC)
8、 equipped witheither a thermal conductivity or a flame ionization detector.The methanol concentration is calculated from the area of themethanol peak using calibration and extraction factors obtainedfrom synthetic blends of known methanol content.5. Significance and Use5.1 Methanol is a common impur
9、ity in propylene. It canhave a deleterious effect on various processes that use propyl-ene as a feedstock.6. Interferences6.1 There are no known interferences using the GC columnsreferenced in this test method. However, any water-solublecomponent that co-elutes with methanol on any other GCcolumn us
10、ed would interfere.7. Apparatus7.1 Gas ChromatographAny GC equipped with eitherflame ionization or thermal conductivity detectors with anoverall sensitivity sufficient to detect at least 4 mg/kg ofmethanol.7.2 ColumnAny GC column that separates methanol fromwater, other alcohols, and any co-extracte
11、d hydrocarbons.NOTE 2See Table 1 for a suitable list of columns and Fig. 1 and Fig.2 for examples of chromatograms. Also, refer to Practice E260 for typicalinstructions in preparing such columns. Alternatively, columns can bepurchased from commercial sources.7.3 Data Handling SystemAny commercially
12、availableGC integrator or GC computer system capable of accuratelyintegrating the area of the methanol peak is satisfactory.7.4 RecorderA strip-chart recorder with a full scale re-sponse of2sorless and a maximum noise rate of 60.3 % fullscale.7.5 Sample Cylinders, 300-mL capacity, stainless steel,Ty
13、pe DOT 3E (12409 kPa (1800 psig) working pressure).1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility ofSubcommittee D02.D0.03 on Propylene.Current edition approved Nov. 15, 2013. Published November 201
14、3. Originallyapproved in 1988. Last previous edition approved in 2005 as D4864 90 (2005).DOI: 10.1520/D4864-90R13.2For 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 th
15、e standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17.6 BalancesAny types capable of weighing a 300-mLsample cylinder and contents accurately to 0.1 g and a 25-mLvolumetric flask and co
16、ntents accurately to 0.0001 g.7.7 Plug Valve,14-in. male NPT or optionally,14-in. maleNPT to 6.35 mm outside diameter (14 in.) tubing. (See Note 3.)7.8 Shut-off Valves,14-in. male NPT to 6.35 mm outsidediameter (14 in.) tubing.7.9 Regulating Valves,14-in. male NPT and14-in. male NPTto14-in. female N
17、PT.7.10 Hex Nipple, SS,14-in. male NPT by 102 mm (4 in.)long.7.11 Hex Coupling, SS,14-in. female NPT by 30 mm (1.2in.) long.7.12 Brass Cap,14-in. NPT or optionally, a tube fitting nut,6.35 mm outside diameter (14 in.). (See Note 3.)7.13 Septum, TFE-fluorocarbon lined, 11-mm diameter.7.14 Syringes, 1
18、0 and 25 L.8. Reagents and Materials8.1 Methanol, reagent grade or better.8.2 Propylene, 92+ % purity containing 0.2 mg/kg (ppmw)methanol.9. Sampling9.1 The propylene sample shall be in the liquified state andbe representative of the material in the storage tank or processline. Also, for purposes of
19、 this method as well as for safetyconsiderations, there must be a vapor space of about 15 % inthe sampling container. It is recommended that samplingcylinders of the type listed in Section 7 be used. They can beequipped with an outage tube to effect the 15 % vapor spacerequirement.TABLE 1 Suitable G
20、as Chromatographic Columns and TemperaturesAColumnNumberColumn Size, m mm Tubing Type Packing Coating, m ThicknessOven Temperature,C1 1.22 6.35 OD SS 15 % Carowax 1540 on 60/80Chromosorb W AW. 902 3.05 4.76 OD SS 80/100 mesh Porapak QS . 1003 3.05 6.35 OD Cu 10 % Carbowax 1540 on30/60 mesh Chromosor
21、b T. 1204 6.10 6.35 OD Cu 10 % Carbowax 1540 on30/60 mesh Chromosorb T. 1205 1.83 2 ID glass 10 % Carbowax 20 M on 80/100 Chromosorb W AW. 706 15 0.53 ID fused silica . J detector: flame ionization.FIG. 1 Chromatograms of Water/Methanol Standard and Water/Methanol/Propylene ExtractANOTE 1Column used
22、: No. 4 of Table 1; detector: thermal conductiv-ity.FIG. 2 Chromatogram of Water/Methanol/Propylene ExtractD4864 90 (2013)210. Preparation of Apparatus10.1 Prepare a water injection device. A suitable device isshown in Fig. 3. However, any other device that will deliverfrom 8 to 15 g of water can be
23、 used.10.2 Prepare a 300-mL sample cylinder for use as a metha-nol cylinder, as shown in Fig. 4. (This cylinder must notcontain an outage tube.) Drilla3to4mm(approximately18in.) hole in a14-in. NPT brass cap, insert an 11-mm septum intoit, and screw it onto the plug valve.NOTE 3As an alternative, th
24、e cylinder can be equipped with14-in.male NPT to a 6.35-mm (14-in.) outside diameter tubing plug valve. Thena 6.35-mm tube fitting nut can be used with the septum, thus avoiding thenecessity of drilling a brass cap.10.3 Set up the chromatograph in accordance with themanufacturers recommendations. In
25、stall the analytical columnand adjust the gas flows and temperatures so that methanol willelute at the desired time. Condition the column at operatingconditions until a stable baseline is recorded at the requiredsensitivity.11. Calibration11.1 Determination of Methanol Response FactorPrepareseveral
26、aqueous solutions of methanol in the same concentra-tion range as expected for samples to be analyzed.NOTE 4This should be approximately 40 to 400 mg/kg (ppmw) on thebasis of propylene sample sizes of 100 to 120 g, water extract volumes ofabout 10 g, and methanol concentrations in the propylene of 4
27、 to40 mg/kg.11.1.1 Methanol Stock SolutionWeigh an empty volumet-ric flask of at least 25 mL capacity to the nearest 0.0001 g. Add20 mL of deionized water to the flask and reweigh. Finally, add2 mL of methanol and again reweigh. Stopper and mixthoroughly. This should contain approximately 73 000 mg/
28、kg(ppm by weight) of methanol. Calculate the exact concentra-tion from the actual weights used. (WarningMethanol istoxic and flammable. Use with adequate ventilation and keepaway from ignition sources.)NOTE 5Refer to Practice D4307 for additional information in prepar-ing this solution and the calib
29、ration solution in 11.1.2.FIG. 3 Water Injection AssemblyFIG. 4 Methanol Cylinder Extraction Factor DeterminationD4864 90 (2013)311.1.2 Methanol Calibration SolutionsIn similar manner,make serial dilutions by weight until two different concentra-tions in the range from 40 to 400 mg/kg are prepared.1
30、1.1.3 With the GC at the proper operating conditions,inject an appropriate quantity of each calibration solution, induplicate, and obtain the area of the methanol peak.NOTE 6The quantity of solution to be injected will depend largely onthe type of detector in use. It varies from about 3 L for FIDs t
31、o 25 L forTCDs.11.1.4 For each solution, calculate the response factor formethanol as follows:F 5 C/H (1)where:F = methanol response factor,C = concentration of methanol, mg/kg, in the blend, andH = area of the methanol peak (average of duplicateinjections).11.1.5 When the response factors at the tw
32、o concentrationsagree within 5 %, average them for use in the final calculationgiven in Section 13.11.2 Determination of Methanol Extraction FactorSincethe methanol is not extracted quantitatively due to solubilitycompetition between the water and the propylene, the extrac-tion efficiency must be de
33、termined experimentally as follows.11.2.1 Collect 100 to 120 g (190 to 230 mL) of methanol-free propylene in a tared 300-mL sample cylinder. Reweigh thecylinder to ensure that it contains the proper amount.(WarningLiquified propylene is at high pressure, can causefrostbite, and is flammable. Use app
34、ropriate care in handling.)11.2.2 As shown in Fig. 4, attach the opposite end of theseptum-equipped methanol cylinder to a vacuum source. Besure that this assembly is leak-free.11.2.3 Open both valves and evacuate the cylinder up to theseptum. Then close the plug valve (next to the septum) andcontin
35、ue the evacuation. Finally, close the other cylinder valve,disconnect the cylinder from the vacuum source, and weigh itto the nearest 0.1 g.11.2.4 Flush a 10 or 25-L syringe several times withmethanol, then fill it to the desired volume (see Table 2), wipeoff the tip, pull the plunger back about 1 L
36、, and weigh it to thenearest 0.0001 g.11.2.5 Open the cylinder plug valve at the septum andimmediately inject the methanol in the syringe through theseptum into the cylinder. Close the valve and immediatelyreweigh the syringe to determine the amount of methanolinjected. The difference between this w
37、eight and that obtainedin 11.2.4 is the weight of methanol injected, W1.11.2.6 Cool the evacuated cylinder to about 20C below thetemperature of the propylene cylinder.11.2.7 As shown in Fig. 5, connect the cylinder containingpropylene to the evacuated cylinder containing methanol via ahex coupling,
38、a short length of 6.35-mm (14-in.) outsidediameter SS tubing, or any other suitable fitting. Beforetightening, flush the connector with a small amount of propyl-ene by briefly opening the lower valve on the propylenecylinder.11.2.8 With both cylinders in a vertical position and thepropylene cylinder
39、 on top, open the valves between them(propylene cylinder first) and allow the liquified propylene toflow into the evacuated cylinder.TABLE 2 Methanol Injection SizesMethanolVolume, LWeight, mgEquivalent Concentration,mg/kg for 100 g propylene54 3610 8 7215 12 10820 16 144FIG. 5 Cylinders Assembly Ex
40、traction Factor DeterminationD4864 90 (2013)411.2.9 Close the valves, disconnect the cylinders, and allowthe lower cylinder to warm to room temperature. Wipe off anywater condensation and allow to dry.11.2.10 Weigh the cylinder containing the methanol andpropylene blend to the nearest 0.1 g. The dif
41、ference betweenthis weight and that obtained in 11.2.3 is the weight ofmethanol and propylene, W2. Calculate the concentration ofmethanol as follows:C 5 W13106!/W2(2)where:C = concentration of methanol, mg/kg,W1= weight of methanol injected, g, andW2= weight of propylene plus methanol, g.11.2.11 Sha
42、ke the cylinder vigorously to mix the propyleneand methanol. Then extract the methanol and analyze theextract as described in 12.2 12.13. Analyze the extract induplicate and average the methanol peak areas.11.2.12 Calculate the methanol content of the extract asdescribed in 13.1, but exclude Fx, the
43、 methanol extractionfactor.11.2.13 Calculate the methanol extraction factor as follows:Fx5 C/D (3)where:Fx= methanol extraction factor,C = methanol concentration calculated in Eq 2, andD = methanol concentration calculated in 11.2.10.NOTE 7It is recommended that the extraction procedure be repeated
44、ata different concentration to verify the accuracy of the factor. Extractionfactors of 1 to 2 are typical.12. Procedure12.1 Weigh the sampling cylinder containing at least 100 gof propylene to the nearest 0.1 g.NOTE 8When practical, it is advisable to weigh the sampling cylinderbefore sampling to ob
45、tain a tare weight.12.2 Pressure deionized water into the injection device in avertical position from the bottom and close the valves.12.3 As shown in Fig. 3, connect the injection device to thesample cylinder using a hex coupling or other suitable device.12.4 Attach the other end to an inert gas so
46、urce at 1724 kPa(250 psig) and purge the lines between V2and V5.12.5 Close V5and tighten the connection at V2.12.6 Pressure the water into the cylinder by opening ValvesV1,V2,V3, and V4, in that order.12.7 Close valves V1and V4and depressure the device viaV5. Then disconnect the cylinder.12.8 Remove
47、 any residual water from the outlet of V4andreweigh the cylinder to 0.1 g. The difference between thisweight and that in 12.1 is the weight of the water, W.12.9 Shake the cylinder vigorously for at least 10 min.12.10 Clamp the cylinder in a vertical position and allow theaqueous phase to settle. (Wh
48、en the cylinder contains an outagetube, it must be at the top of the cylinder.)12.11 Carefully open the bottom valve and drain the aque-ous phase containing the methanol into an appropriate con-tainer (vial or flask) and cap it. (WarningAs soon as theaqueous phase drains, high-pressure liquified pro
49、pylene willsurge out.)12.12 With the GC at the proper operating conditions, injectthe appropriate size of the aqueous extract for the GC andcalibration being used.12.13 Safely vent off the remaining propylene in the samplecylinder and reweigh it to 0.1 g (unless the cylinder wasalready tared.) The difference between this weight and that in12.1 is the weight of the propylene extracted, G.13. Calculation13.1 Calculate the methanol content of the propylene usingthe following equation:Methanol, mg/kg ppm wt! 5 AF
