1、Designation: D3231 13Standard 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 Department of Defense.1. Scope*1.1 This test method covers the determination of phospho-rus generally present as pe
3、ntavalent phosphate esters or salts,or both, in gasoline. This test method is applicable for thedetermination of phosphorus in the range from 0.2 to 40 mgP/litre or 0.0008 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 are for in
4、formationonly.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 the applica-bility of regulatory limitations prior to use.
5、For specificwarning statements, see Section 6 and 9.5.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evalu
6、ate AnalyticalMeasurement System PerformanceE832 Specification for Laboratory Filter Papers3. Summary of Test Method3.1 Organic 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 sulfa
7、te. The absorbance of the Molybdenum Bluecomplex is proportional to the phosphorus concentration in thesample and is read at approximately 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 leve
8、ltherefore is kept low.5. Apparatus5.1 Buret, 10-mL capacity, 0.05-mL subdivisions.5.2 Constant-Temperature Bath, equipped to hold several100-mL volumetric flasks submerged to the mark. Bath musthave a large enough reservoir or heat capacity to keep thetemperature at 82.2 to 87.8C (180 to 190F) duri
9、ng the entireperiod of sample heating.NOTE 1If the temperature of the hot water bath drops below 82.2C(180F), the color 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,
10、Class G for fineprecipitates as defined in Specification E832.5.5 Ignition DishCoors porcelain evaporating dish, glazedinside and outside, with pourout (Size No. 00A, diameter 75mm, capacity 70 mL).5.6 Spectrophotometer, equipped with a tungsten lamp, ared-sensitive phototube capable of operating at
11、 830 nm andwith absorption cells that have a 5-cm light path.5.7 Thermometer, ASTM 34C or 34F, range from 25 to105C (77 to 221F).NOTE 2Other temperature measuring devices, such as thermocouplesor resistance thermometers, may be used when the temperature readingsobtained by these devices are determin
12、ed to produce the same results thatare obtained when mercury-in-glass thermometers are used. The precisionand bias given in Section 12 may or may not apply in such cases since thepublished precision is based on an interlaboratory study where onlymercury-in-glass thermometers were used. No informatio
13、n 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.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubri
14、cants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved June 15, 2013. Published July 2013. Originallyapproved in 1973. Last previous edition approved in 2011 as D3231 11. DOI:10.1520/D3231-13.2For referenced ASTM standards, visit the ASTM website,
15、 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 end of this standardCopyright ASTM International, 100 Barr Harbor Drive
16、, PO Box C700, West Conshohocken, PA 19428-2959. United States15.10 Syringe, Luer-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.
17、 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 specifications are available.3Other g
18、rades 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 WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Types II or
19、III of Specification D1193.6.3 Ammonium Molybdate Solution(WarningPoisonous gas may 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.)
20、Using graduated cylinders for measurement, add slowly, withcontinuous stirring, 225 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)6M
21、o7O244H2O). Stir until solution is completeand transfer to a 1000-mL flask. Dilute to the mark with water.6.4 Hydrazine Sulfate Solution Dissolve 1.5 g of hydra-zine sulfate (Warning Cancer suspect agent.) (H2NNH2H2SO4) in 1 L of water, measured with a graduated cylinder.(WarningThis solution is not
22、 stable. Keep it tightly stop-pered and in the dark. Prepare a fresh solution after 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 m
23、L with water.NOTE 3This reagent is unstable and is to be used within about 4 h.Prepare it immediately before use. Each determination (including theblank) uses 50 mL.6.6 Phosphorus, Stock Solution, Standard (1.00 mgP/mL)Dry approximately5gofpotassium dihydrogenphosphate (KH2PO4) in an oven at 105 to
24、110C (221 to230F) for 3 h. Dissolve 4.393 6 0.002 g of the reagent in 150mL, measured with a graduate cylinder, of dilute sulfuric acid(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 so
25、lution into a 1000-mLvolumetric flask and dilute to the mark with water.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 wh
26、en adding concentrated sulfuric acid to water.) Usinggraduated cylinders for measurement, add slowly, with con-tinuous stirring, 100 mL of H2SO4(relative density 1.84) to 1L of water contained in a beaker placed in a bath of cold water.6.9 Zinc Oxide(WarningSee 6.8.) (WarningHigh-bulk density zinc o
27、xide can cause spattering. Density ofapproximately 0.5 g/cm3has been found 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
28、 of the testing process asdescribed in Section 11.7. Sampling7.1 Take samples in accordance with the instructions inPractice D4057.7.2 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
29、.001 or less 0.0038 or less 10.0NOTE 4When using a 10-mL sample, 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, 0.0,0.5,
30、1.0, 1.5, 2.0, 3.0, 3.5, and 4.0 mL of phosphorus standardsolution 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 samp
31、lesbeing analyzed.8.4 Dispense 50 mL of the molybdate-hydrazine reagentinto each volumetric flask. Mix immediately by swirling.8.5 Dilute to 100 mL with water.8.6 Mix well and place in the constant-temperature bath sothat the contents of the flask are submerged below the level ofthe bath. Maintain b
32、ath temperature at 82.2 to 87.8C (180 to190F) 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 2.8C (5F) below room tempera-ture.3Reagent Chemicals, American Chemical Society Specifications , Am
33、ericanChemical 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. Pharmacopeial Convention, Inc. (U
34、SPC), Rockville,MD.D3231 132NOTE 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
35、in a 5-cm cell,determine the wavelength 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 dis
36、tilled water. If using adual-beam 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 absorbanc
37、e of each calibration sampleincluding 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 con
38、tamination. It is suggestedthat 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 correct
39、edabsorbance of each standard solution 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 o
40、ften contain alkali phosphatesthat 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 avoida
41、nce of contamination in order toobtain satisfactory accuracy with the small amounts of phos-phorus involved.9.3 Transfer 2 6 0.2 g of zinc oxide into a conical pile in aclean, 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
42、 gasoline sample (Note 6) (see 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
43、 required at 15.6C (60F) and 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 suff
44、icient time for the gasoline 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
45、 approximately 0.2 g). Tap 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
46、containing the sample andblank in a hot muffle furnace set at a temperature of 621 to704C (1150 to 1300F) 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 ign
47、ition 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 heating the ignition dishwith a Meker burner, gradually increa
48、sing the intensity of heat until thecarbon from the sides of the dish has been burned; cool to roomtemperature.9.10 Dispense 25 mL of dilute sulfuric acid (6.8) into eachignition dish. While dispensing, carefully wash all traces ofzinc oxide from the sides of the ignition dish.9.11 Cover the ignitio
49、n dish with a borosilicate watch glassand warm the ignition dish on a hot plate until the zinc oxideis completely dissolved.9.12 Transfer the solution through filter paper to a 100-mLvolumetric flask. Rinse the watch glass and the dish severaltimes with distilled water (do not exceed 25 mL) and transferthe washings through the filter paper to the volumetric flask.9.13 Prepare the molybdate-hydrazine reagent.9.14 Dispense 50 mL of the molybdate-hydrazine reagentinto each 100-mL volumetric flask. Mix immediately byswirling.9.15 Di
