1、Designation: D3231 18Standard Test Method forPhosphorus in Gasoline1This standard is issued under the fixed designation D3231; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indic
2、ates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This test method covers the determination of phospho-rus generally present
3、as pentavalent phosphate esters or salts,or both, in gasoline. This test method is applicable for thedetermination of phosphorus in the range from 0.2 mg to 40 mgP/L or 0.0008 g to 0.15 g P/U.S. gal.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses afte
4、r SI units areprovided for information only and are not considered standard.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, health, and environmental pract
5、ices and deter-mine the applicability of regulatory limitations prior to use.For specific warning statements, see Section 6 and 9.5.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles fo
6、r theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum Prod
7、uctsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceE832 Specification for Laboratory Filter Papers3. Summary of Test Method3.1 Organic
8、 matter in the sample is decomposed by ignitionin the presence of zinc oxide. The residue is dissolved insulfuric acid and reacted with ammonium molybdate andhydrazine sulfate. The absorbance of the Molybdenum Bluecomplex is proportional to the phosphorus concentration in thesample and is read at ap
9、proximately 820 nm in a 5 cm cell.4. Significance and Use4.1 Phosphorus in gasoline will damage catalytic convertorsused in automotive emission control systems, and its leveltherefore is kept low.5. Apparatus5.1 Buret, 10 mL capacity, 0.05 mL subdivisions.5.2 Constant-Temperature Bath, equipped to h
10、old several100 mL volumetric flasks submerged to the mark. Bath musthave a large enough reservoir or heat capacity to keep thetemperature at 82.2 C to 87.8 C (180 F to 190 F) during theentire period of sample heating.NOTE 1If the temperature of the hot water bath drops below 82.2 C(180 F), the color
11、 development cannot be complete.5.3 Cooling Bath, equipped to hold several 100 mL volu-metric flasks submerged to the mark in ice water.5.4 Filter Paper, for quantitative analysis, Class G for fineprecipitates as defined in Specification E832.5.5 Ignition DishCoors porcelain evaporating dish, glazed
12、inside and outside, with pourout (Size No. 00A, diameter75 mm, capacity 70 mL).5.6 Spectrophotometer, equipped with a tungsten lamp, ared-sensitive phototube capable of operating at 830 nm andwith absorption cells that have a 5 cm light path.5.7 Thermometer, ASTM 34C or 34F, range from 25 C to105 C
13、(77 F to 221 F).NOTE 2Other temperature measuring devices, such as thermocouplesor resistance thermometers, may be used when the temperature readingsobtained by these devices are determined to produce the same results thatare obtained when mercury-in-glass thermometers are used. The precision1This t
14、est method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved April 1, 2018. Published April 2018. Originallyapproved in 1973. Last previous edition a
15、pproved in 2013 as D3231 13. DOI:10.1520/D3231-18.2For 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
16、of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in
17、the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1and bias given in Section 12 may or may not apply in such cases since thepublished precision is based on an interla
18、boratory study where onlymercury-in-glass thermometers were used. No information on the effecton precision when using alternative temperature measuring devices isavailable.5.8 Volumetric Flask, 100 mL with ground-glass stopper.5.9 Volumetric Flask, 1000 mL with ground-glass stopper.5.10 Syringe, Lue
19、r-Lok, 10 mL equipped with 5 cm,22 gauge needle.5.11 Pipets, or equivalent volume dispensing devices, fordelivering the necessary volumes of dilute sulfuric acid (6.8)and molybdate-hydrazine reagent used in this test.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.
20、 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, provided it is first ascertained that the reagent is ofsufficie
21、ntly high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Types II or III of Specification D1193.6.3 Ammonium Molybdate Solution(WarningPoisonous gas m
22、ay be liberated in fire. Irritating to skin andeyes. Harmful if swallowed.) (WarningIn addition toother precautions, wear a face shield, rubber gloves, and arubber apron when adding concentrated sulfuric acid to water.)Using graduated cylinders for measurement, add slowly, withcontinuous stirring, 2
23、25 mL of concentrated sulfuric acid(H2SO4, relative density 1.84) to 500 mL of water contained ina beaker placed in a bath of cold water. Cool to roomtemperature, and add 20 g of ammonium molybdate tetrahy-drate (NH4)6Mo7O244H2O). Stir until solution is completeand transfer to a 1000 mL flask. Dilut
24、e to the mark with water.6.4 Hydrazine Sulfate Solution Dissolve 1.5 g of hydra-zine sulfate (WarningCancer suspect agent.) (H2NNH2H2SO4) in 1 L of water, measured with a graduated cylinder.(WarningThis solution is not stable. Keep it tightly stop-pered and in the dark. Prepare a fresh solution afte
25、r 3 weeks.)6.5 Molybdate-Hydrazine ReagentPipet 25 mL of ammo-nium molybdate solution into a 100 mL volumetric flaskcontaining approximately 50 mL of water, add by pipet 10 mLof H2NNH2H2SO4solution, and dilute to 100 mL with water.NOTE 3This reagent is unstable and is to be used within about 4 h.Pre
26、pare it immediately before use. Each determination (including theblank) uses 50 mL.6.6 Phosphorus, Stock Solution, Standard (1.00 mgP/mL)Dry approximately 5 g of potassium dihydrogen phos-phate (KH2PO4) in an oven at 105 C to 110 C (221 F to230 F) for 3 h. Dissolve 4.393 g 6 0.002 g of the reagent i
27、n150 mL, measured with a graduate cylinder, of dilute sulfuricacid (6.8) contained in a 1000 mL volumetric flask. Dilute withwater to the mark.6.7 Phosphorus Solution, Standard (10.0 g P/mL)Pipet10 mL of phosphorus stock standard solution into a 1000 mLvolumetric flask and dilute to the mark with wa
28、ter.6.8 Dilute Sulfuric Acid (one part H2SO4and 10 partswater)(WarningConcentrated sulfuric acid causes severeburns. Strong oxidizer.) (WarningIn addition to otherprecautions, wear a face shield, rubber gloves, and a rubberapron when adding concentrated sulfuric acid to water.) Usinggraduated cylind
29、ers for measurement, add slowly, with con-tinuous stirring, 100 mL of H2SO4(relative density 1.84) to1 L of water contained in a beaker placed in a bath of coldwater.6.9 Zinc Oxide(WarningSee 6.8.) (WarningHigh-bulk density zinc oxide can cause spattering. Density ofapproximately 0.5 g cm3has been f
30、ound satisfactory.)6.10 Quality Control (QC) Samples, preferably are portionsof one or more liquid petroleum materials that are stable andrepresentative of the samples of interest. These QC samplescan be used to check the validity of the testing process asdescribed in Section 11.7. Sampling7.1 Take
31、samples in accordance with the instructions inPractices D4057 or D4177.7.2 Use the following table as a guide for selecting samplesize:Phosphorus,mg/L Equivalent, g/galSample Size,mL2.540 0.010.15 1.001.320 0.0050.075 2.000.913 0.00370.05 3.001 or less 0.0038 or less 10.0NOTE 4When using a 10 mL sam
32、ple, ignite aliquots of 2 mL ofsample in the same 2 g portion of zinc oxide; allow the zinc oxide to coolbefore adding the next 2 mL aliquot of gasoline (Note 6).8. Calibration8.1 Transfer by buret, or a volumetric transfer pipet, 0.0 mL,0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, 3.0 mL, 3.5 mL, and 4.0 mLof p
33、hosphorus standard solution into 100 mL volumetric flasks.8.2 Dispense 10 mL of dilute sulfuric acid (6.8) into eachflask. Mix immediately by swirling.8.3 Prepare the molybdate-hydrazine reagent. Prepare suf-ficient volume of reagent based on the number of samplesbeing analyzed.8.4 Dispense 50 mL of
34、 the molybdate-hydrazine reagentinto each volumetric flask. Mix immediately by swirling.8.5 Dilute to 100 mL with water.3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemic
35、al Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D3231 1828.6 Mix well and place in the constant-temperature bath sothat the contents of the flas
36、k are submerged below the level ofthe bath. Maintain bath temperature at 82.2 C to 87.8 C(180 F to 190 F) for 25 min (Note 1).8.7 Transfer the flask to the cooling bath and cool thecontents rapidly to room temperature. Do not allow thesamples to cool more than 2.8 C (5 F) below room tempera-ture.NOT
37、E 5Place a chemically clean thermometer in one of the flasks tocheck the temperature.8.8 After cooling the flasks to room temperature, removethem from the cooling water bath and allow them to stand for10 min at room temperature.8.9 Using the 2.0 mL phosphorus standard in a 5 cm cell,determine the wa
38、velength near 820 nm that gives maximumabsorbance. The wavelength giving maximum absorbanceshould not exceed 830 nm.8.9.1 Using the red-sensitive phototube and 5 cm cells,adjust the spectrophotometer to zero absorbance at the wave-length of maximum absorbance using distilled water. If using adual-be
39、am spectrophotometer, place distilled water in bothcells. Use the wavelength of maximum absorbance in thedetermination of calibration readings and future sample read-ings.8.9.2 The use of 1 cm cells for the higher concentrations ispermissible.8.10 Measure the absorbance of each calibration sampleinc
40、luding the blank (0.0 mL phosphorus standard) at thewavelength of maximum absorbance with distilled water in thereference cell. Great care shall be taken to avoid possiblecontamination. If the absorbance of the blank exceeds 0.04 (for5 cm cell), check for source of contamination. It is suggestedthat
41、 the results be disregarded and the test be rerun with freshreagents and clean glassware.8.11 Correct the absorbance of each standard solution bysubtracting the absorbance of the blank (0.0 mL phosphorusstandard).8.12 Prepare a calibration curve by plotting the correctedabsorbance of each standard s
42、olution against micrograms ofphosphorus. One millilitre of phosphorus solution standardprovides 10 g of phosphorus.9. Procedure9.1 Clean all glassware before use with cleaning acid or bysome procedure that does not involve use of commercialdetergents. These compounds often contain alkali phosphatest
43、hat are strongly adsorbed by glass surfaces and are notremoved by ordinary rinsing. It is desirable to segregate aspecial stock of glassware for use only in the determination ofphosphorus.9.2 Observe the usual precautions of cleanliness, carefulmanipulation, and avoidance of contamination in order t
44、oobtain satisfactory accuracy with the small amounts of phos-phorus involved.9.3 Transfer 2 g 6 0.2 g of zinc oxide into a conical pile ina clean, dry, unetched ignition dish.9.4 Make a deep depression in the center of the zinc oxidepile with a stirring rod.9.5 Pipet the gasoline sample (Note 6) (se
45、e 7.2 for suggestedsample volume) into the depression in the zinc oxide.(WarningIn addition to other precautions, cool the ignitiondish before adding the additional aliquots of gasoline to avoida flash fire.) Record the temperature of the fuel if thephosphorus content is required at 15.6 C (60 F) an
46、d makecorrection as directed in 10.2.NOTE 6For the 10 mL sample use multiple additions and a syringe.Hold the tip of the needle at approximately23 of the depth of the zincoxide layer and slowly deliver 2 mL of the sample; fast sample deliverymay give low results. Give sufficient time for the gasolin
47、e to be absorbedby the zinc oxide. Follow step 9.6. Cool the dish to room temperature.Repeat steps 9.5 and 9.8 until all the sample has been burned.9.6 Cover the sample with a small amount of fresh zincoxide from the reagent bottle (use the tip of a small spatula todeliver approximately 0.2 g). Tap
48、the sides of the ignition dishto pack the zinc oxide.9.7 Prepare the blank, using the same amount of zinc oxidein an ignition dish.9.8 Ignite the gasoline, using the flame from a Bunsenburner. Allow the gasoline to burn to extinction (Note 6).9.9 Place the ignition dishes containing the sample andbl
49、ank in a hot muffle furnace set at a temperature of 621 C to704 C (1150 F to 1300 F) for 10 min. Remove and cool theignition dishes. When cool gently tap the sides of the dish toloosen the zinc oxide. Again place the dishes in the mufflefurnace for 5 min. Remove and cool the ignition dishes to roomtemperature. The above treatment is usually sufficient to burnthe carbon. If the carbon is not completely burned off, place thedish into the furnace for further 5 min periods.NOTE 7Step 9.9 can also be accomplished by heatin
