1、Designation: D 3231 07An American National StandardStandard Test Method forPhosphorus in Gasoline1This standard is issued under the fixed designation D 3231; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. 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 Department of Defense.1. Scope*1.1 This test method covers the determination of pho
3、spho-rus generally present 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 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 as thestandard. The va
4、lues given in parentheses are for informationonly.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 r
5、egulatory limitations prior to use. For specificwarning statements, see Section 6 and 9.5.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 6299 Practice for Applying Statistical Quality AssuranceT
6、echniques to Evaluate Analytical Measurement SystemPerformanceE 832 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
7、 andhydrazine sulfate. 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 sy
8、stems, and its leveltherefore 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
9、 (180 to 190F) during 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 quan
10、titative analysis, Class G for fineprecipitates as defined in Specification E 832.5.5 Ignition DishCoors porcelain evaporating dish,glazed inside and outside, with pourout (Size No. 00A,diameter 75 mm, capacity 70 mL).5.6 Spectrophotometer, equipped with a tungsten lamp, ared-sensitive phototube cap
11、able 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 to105C (77 to 221F).5.8 Volumetric Flask, 100-mL with ground-glass stopper.5.9 Volumetric Flask, 1000-mL with ground-glass stopper.5.10 Syringe, Luer-Lok, 10-mL equipped w
12、ith 5-cm, 22-gauge needle.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1973. Last pre
13、vious edition approved in 2002 as D 323102.2For 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.1*A Summary of Cha
14、nges section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall re
15、agents 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 ofsufficiently high purity to permit its use without lessening t
16、heaccuracy 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 D 1193.6.3 Ammonium Molybdate Solution(WarningPoisonous gas may be liberated in fire. Irritating to skin andeyes.
17、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, 225 mL of concentrated sulfuric acid(H2SO4, relative d
18、ensity 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. Dilute to the mark with water.6.4 Hydrazine Sulfate Soluti
19、onDissolve 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 after 3 weeks.)6.5 Molybdate-Hydrazine ReagentPipet 25 mL
20、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 2This reagent is unstable and is to be used within about 4 h.Prepare it immediately before use. Each determination (in
21、cluding theblank) uses 50 mL.6.6 Phosphorus, Stock Solution, Standard (1.00 mgP/mL)Dry approximately5gofpotassium dihydrogenphosphate (KH2PO4) in an oven at 105 to 110C (221 to230F) for 3 h. Dissolve 4.393 6 0.002 g of the reagent in 150mL, measured with a graduate cylinder, of H2SO4(1 + 10)containe
22、d in a 1000-mL volumetric flask. Dilute with water tothe 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 water.6.8 Sulfuric Acid (1 + 10)(WarningConcentrated sul-furic acid causes severe b
23、urns. Strong oxidizer.) (WarningInaddition to other precautions, wear a face shield, rubber gloves,and a rubber apron when adding concentrated sulfuric acid towater.) Using graduated cylinders for measurement, addslowly, with continuous stirring, 100 mL of H2SO4(relativedensity 1.84) to 1 L of water
24、 contained in a beaker placed in abath of cold water.6.9 Zinc Oxide(WarningSee 6.8.) (WarningHigh-bulk density zinc oxide 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 mate
25、rials 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 samples in accordance with the instructions inPractice D 4057.7.2 Use the following table as a guide for selectin
26、g 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 3When 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
27、 next 2-mL aliquot of gasoline (Note 5).8. Calibration8.1 Transfer by buret, or a volumetric transfer pipet, 0.0,0.5, 1.0, 1.5, 2.0, 3.0, 3.5, and 4.0 mL of phosphorus standardsolution into 100-mL volumetric flasks.8.2 Pipet 10 mL of H2SO4(1 + 10) into each flask. Miximmediately by swirling.8.3 Prep
28、are the molybdate-hydrazine reagent. Prepare suf-ficient volume of reagent based on the number of samplesbeing analyzed.8.4 Pipet 50 mL of the molybdate-hydrazine reagent to eachvolumetric flask. Mix immediately by swirling.8.5 Dilute to 100 mL with water.8.6 Mix well and place in the constant-tempe
29、rature bath sothat the contents of the flask are submerged below the level ofthe bath. Maintain bath 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.
30、8C (5F) below room tempera-ture.NOTE 4Place 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 stand
31、ard 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
32、 distilled water. If using a3Reagent 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
33、 the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D3231072dual-beam spectrophotometer, place distilled water in bothcells. Use the wavelength of maximum absorbance in thedetermination of calibration readings and future sample read-ings.8.
34、9.2 The use of 1-cm cells for the higher concentrations ispermissible.8.10 Measure the absorbance 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 possibleco
35、ntamination. If the absorbance of the blank exceeds 0.04 (for5-cm cell), check for source of contamination. 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 o
36、f the blank (0.0 mL phosphorusstandard).8.12 Prepare a calibration curve by plotting the correctedabsorbance 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 cleani
37、ng acid or bysome procedure that does not involve use of commercialdetergents. These compounds often 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 determinatio
38、n ofphosphorus.9.2 Observe the usual precautions of cleanliness, carefulmanipulation, and avoidance 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.
39、9.4 Make a deep depression in the center of the zinc oxidepile with a stirring rod.9.5 Pipet the gasoline sample (Note 5) (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 o
40、f gasoline to avoida flash fire.) Record the temperature of the fuel if thephosphorus content is required at 15.6C (60F) and makecorrection as directed in 10.2.NOTE 5For the 10-mL sample use multiple additions and a syringe.Hold the tip of the needle at approximately23 of the depth of the zincoxide
41、layer and slowly deliver 2 mL of the sample; fast sample deliverymay give low results. Give sufficient 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 s
42、mall amount of fresh zincoxide from the reagent bottle (use the tip of a small spatula todeliver 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
43、a Bunsenburner. Allow the gasoline to burn to extinction (Note 5).9.9 Place the ignition dishes 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 toloose
44、n 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 6Ste
45、p 9.9 can also be accomplished by heating the ignition dishwith a Meker burner, gradually increasing the intensity of heat until thecarbon from the sides of the dish has been burned; cool to roomtemperature.9.10 Pipet 25 mL of H2SO4(1 + 10) into each ignition dish.While pipeting, carefully wash all
46、traces of zinc oxide from thesides of the ignition dish.9.11 Cover the ignition 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
47、 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 Add 50 mL of the molybdate-hydrazine reagent bypipet to each 100-mL volumetric flask. Mix immediately bysw
48、irling.9.15 Dilute to 100 mL with water and mix well. Removestoppers from flasks after mixing.9.16 Place the 100-mL flasks in the constant-temperaturebath for 25 min so that the contents of the flasks are below theliquid level of the bath. The temperature of the bath should be82.2 to 87.8C (180 to 1
49、90F) (Note 1).9.17 Transfer the 100-mL flasks to the cooling bath and coolthe contents rapidly to room temperature (Note 4).9.18 Allow the samples to stand at room temperature beforemeasuring the absorbance.NOTE 7The color developed is stable for at least 4 h.9.19 Set the spectrophotometer to the wavelength of maxi-mum absorbance as determined in 8.9. Adjust the spectropho-tometer to zero absorbance, using distilled water. If using adual-beam spectrophotometer, place distilled water in bothcells.9.20 Measure the absorbance of the
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