1、Designation: D 4864 90 (Reapproved 2005)An American National StandardStandard Test Method forDetermination of Traces of Methanol in PropyleneConcentrates by Gas Chromatography1This standard is issued under the fixed designation D 4864; the number immediately following the designation indicates the y
2、ear oforiginal adoption or, in 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.This standard has been approved for use by agencies of the Depar
3、tment of Defense.1. Scope1.1 This test method covers the determination of methanolin propylene concentrates in the range of approximately 4 to 40mg/kg (parts-per-million by weight).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informatio
4、nonly.NOTE 1There is no direct acceptable SI equivalent for screw threads.1.3 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
5、 the applica-bility of regulatory limitations prior to use. Specific warningstatements are given in 11.1.1, 11.2.1, and 12.11.2. Referenced Documents2.1 ASTM Standards:2D 4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsE 260 Practice for Packed Column Gas Chromatography3
6、. Terminology3.1 Definitions:3.1.1 propylene concentrateconcentrate containing morethan 90 % propylene.3.2 Definitions 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
7、cylinder. It is used tofacilitate removal of a set quantity of liquified sample toprevent overpressuring the cylinder.4. 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 t
8、he water/methanolphase is withdrawn. A reproducible volume of the extract isthen injected into a gas chromatograph (GC) equipped witheither a thermal conductivity or a flame ionization detector.The methanol concentration is calculated from the area of themethanol peak using calibration and extractio
9、n factors obtainedfrom synthetic blends of known methanol content.5. Significance and Use5.1 Methanol is a common impurity in propylene. It canhave a deleterious effect on various processes that use propy-lene as a feedstock.6. Interferences6.1 There are no known interferences using the GC columnsre
10、ferenced in this test method. However, any water-solublecomponent that co-elutes with methanol on any other GCcolumn used would interfere.7. Apparatus7.1 Gas ChromatographAny GC equipped with eitherflame ionization or thermal conductivity detectors with anoverall sensitivity sufficient to detect at
11、least 4 mg/kg ofmethanol.7.2 ColumnAny GC column that separates methanol fromwater, other alcohols, and any co-extracted 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 E 260 for typicalinstructions in preparin
12、g such columns. Alternatively, columns can bepurchased from commercial sources.7.3 Data Handling SystemAny commercially availableGC integrator or GC computer system capable of accuratelyintegrating the area of the methanol peak is satisfactory.1This test method is under the jurisdiction of ASTM Comm
13、ittee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.D0.03 on Propylene.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1988. Last previous edition approved in 2000 as D 4864 90 (2000)e1.2For referenced ASTM standards
14、, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
15、428-2959, United States.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,Type DOT 3E (12409 kPa (1800 psig) working pressure).7.6 BalancesAny types capable of weighing a 300-m
16、Lsample cylinder and contents accurately to 0.1 g and a 25-mLvolumetric flask and contents 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 i
17、n.) tubing.7.9 Regulating Valves,14-in. male NPT and14-in. male NPTto14-in. female NPT.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.
18、). (See Note 3.)7.13 Septum, TFE-fluorocarbon lined, 11-mm diameter.7.14 Syringes, 10 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 repr
19、esentative of the material in the storage tank or processline. Also, for purposes of this method as well as for safetyconsiderations, there must be a vapor space of about 15 % inthe sampling container. It is recommended that samplingTABLE 1 Suitable Gas Chromatographic Columns and TemperaturesAColum
20、nNumberColumn Size, m 3 mm Tubing Type Packing Coating, m ThicknessOven Temperature,C1 1.22 3 6.35 OD SS 15 % Carowax 1540 on 60/80Chromosorb W AW. 902 3.05 3 4.76 OD SS 80/100 mesh Porapak QS . 1003 3.05 3 6.35 OD Cu 10 % Carbowax 1540 on30/60 mesh Chromosorb T. 1204 6.10 3 6.35 OD Cu 10 % Carbowax
21、 1540 on30/60 mesh Chromosorb T. 1205 1.83 3 2 ID glass 10 % Carbowax 20 M on 80/100 Chromosorb W AW. 706153 0.53 ID fused silica . J detector: flame ionization.FIG. 1 Chromatograms of Water/Methanol Standard and Water/Methanol/Propylene ExtractANOTEColumn used: No. 4 of Table 1; detector: thermal c
22、onductivity.FIG. 2 Chromatogram of Water/Methanol/Propylene ExtractD 4864 90 (2005)2cylinders of the type listed in Section 7 be used. They can beequipped with an outage tube to effect the 15 % vapor spacerequirement.10. Preparation of Apparatus10.1 Prepare a water injection device. A suitable devic
23、e isshown in Fig. 3. However, any other device that will deliverfrom 8 to 15 g of water can be 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 ca
24、p, insert an 11-mm septum intoit, and screw it onto the plug valve.NOTE 3As an alternative, the 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 b
25、rass cap.10.3 Set up the chromatograph in accordance with themanufacturers recommendations. Install 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 re
26、quiredsensitivity.11. Calibration11.1 Determination of Methanol Response FactorPrepareseveral 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 t
27、o 120 g, water extract volumes ofabout 10 g, and methanol concentrations in the propylene of 4 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 metha
28、nol and again reweigh. Stopper and mixthoroughly. This should contain approximately 73 000 mg/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.)FIG.
29、 3 Water Injection AssemblyFIG. 4 Methanol Cylinder Extraction Factor DeterminationD 4864 90 (2005)3NOTE 5Refer to Practice D 4307 for additional information in pre-paring this solution and the calibration solution in 11.1.2.11.1.2 Methanol Calibration SolutionsIn similar manner,make serial dilution
30、s by weight until two different concentra-tions in the range from 40 to 400 mg/kg are prepared.11.1.3 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
31、 injected will depend largely onthe type of detector in use. It varies from about 3 L for FIDs to 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
32、of the methanol peak (average of duplicateinjections).11.1.5 When the response factors at the two 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
33、solubilitycompetition between the water and the propylene, the extrac-tion efficiency must be determined 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 amoun
34、t.(WarningLiquified propylene is at high pressure, can causefrostbite, and is flammable. Use appropriate 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
35、 evacuate the cylinder up to theseptum. Then close the plug valve (next to the septum) andcontinue 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, th
36、en fill it to the desired volume (see Table 2), wipeoff the tip, pull the plunger back about 1 L, 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 immediate
37、lyreweigh the syringe to determine the amount of methanolinjected. The difference between this weight 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 th
38、e cylinder containingpropylene to the evacuated cylinder containing methanol via ahex coupling, 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 propy-lene by briefly opening the lower valve on t
39、he propylenecylinder.11.2.8 With both cylinders in a vertical position and thepropylene cylinder on top, open the valves between themTABLE 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 DeterminationD 4864 90 (2005)4(propylene cylinder first) and allow the liquified propylene toflow into the evacuated cylinder.11.2.9 Close the valves, disconnect the cylinders, and allowthe lower cylinder to warm to room temperature. Wipe off anywater condensation and allow to dry.11
41、.2.10 Weigh the cylinder containing the methanol andpropylene blend to the nearest 0.1 g. The difference betweenthis weight and that obtained in 11.2.3 is the weight ofmethanol and propylene, W2. Calculate the concentration ofmethanol as follows:C 5 W13 106!/W2(2)where:C = concentration of methanol,
42、 mg/kg,W1= weight of methanol injected, g, andW2= weight of propylene plus methanol, g.11.2.11 Shake 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 ar
43、eas.11.2.12 Calculate the methanol content of the extract asdescribed in 13.1, but exclude Fx, the 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 conc
44、entration calculated in 11.2.10.NOTE 7It is recommended that the extraction procedure be repeatedat a 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 neare
45、st 0.1 g.NOTE 8When practical, it is advisable to weigh the sampling cylinderbefore sampling to obtain 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 c
46、ylinder using a hex coupling or other suitable device.12.4 Attach the other end to an inert gas source 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.1
47、2.7 Close valves V1and V4and depressure the device viaV5. Then disconnect the cylinder.12.8 Remove 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 leas
48、t 10 min.12.10 Clamp the cylinder in a vertical position and allow theaqueous phase to settle. (When 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 (
49、vial or flask) and cap it. (WarningAs soon as theaqueous phase drains, high-pressure liquified propylene 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 con
