1、Designation:D323107 Designation: D3231 11Standard 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
2、in parentheses indicates 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 phosphorus gene
3、rally present as pentavalent phosphate esters or salts, or both,in gasoline. This test method is applicable for the determination of phosphorus in the range from 0.2 to 40 mg P/litre or 0.0008to 0.15 g P/U.S. gal.1.2 The values stated in SI units are to be regarded as standard. The values given in p
4、arentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimita
5、tions prior to use. For specific warning statements, see Section 6 and 9.5.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assurance and Control Chart
6、ing Techniques to Evaluate AnalyticalMeasurement System PerformanceE832 Specification for Laboratory Filter Papers3. Summary of Test Method3.1 Organic matter in the sample is decomposed by ignition in the presence of zinc oxide. The residue is dissolved in sulfuricacid and reacted with ammonium moly
7、bdate and hydrazine sulfate. The absorbance of the Molybdenum Blue complex isproportional to the phosphorus concentration in the sample and is read at approximately 820 nm in a 5-cm cell.4. Significance and Use4.1 Phosphorus in gasoline will damage catalytic convertors used in automotive emission co
8、ntrol systems, and its level thereforeis kept low.5. Apparatus5.1 Buret, 10-mL capacity, 0.05-mL subdivisions.5.2 Constant-Temperature Bath, equipped to hold several 100-mL volumetric flasks submerged to the mark. Bath must have alarge enough reservoir or heat capacity to keep the temperature at 82.
9、2 to 87.8C (180 to 190F) during the entire period of sampleheating.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 volumetric flasks submerged to the mark in ice water.5.4 Filter Paper
10、, for quantitative analysis, Class G for fine precipitates as defined in Specification E832.5.5 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, a red-sensitive p
11、hototube capable of operating at 830 nm and withabsorption cells that have a 5-cm light path.1This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03 onElemental Analysis.Current edition approved Ma
12、yJan. 1, 2007.2011. Published June 2007.February 2011. Originally approved in 1973. Last previous edition approved in 20022007 asD323102.D323107. DOI: 10.1520/D3231-07.10.1520/D3231-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceas
13、tm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Beca
14、useit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appea
15、rs at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.7 Thermometer, ASTM 34C or 34F, range from 25 to 105C (77 to 221F). , ASTM 34C or 34F, range from 25 to 105C (77to 221F).NOTE 2Other temperature measurin
16、g devices, such as thermocouples or resistance thermometers, may be used when the temperature readingsobtained by these devices are determined to produce the same results that are obtained when mercury-in-glass thermometers are used. The precision andbias given in Section 12 may or may not apply in
17、such cases since the published precision is based on an interlaboratory study where onlymercury-in-glass thermometers were used. No information on the effect on precision when using alternative temperature measuring devices is available.5.8 Volumetric Flask, 100-mL with ground-glass stopper.5.9 Volu
18、metric Flask, 1000-mL with ground-glass stopper.5.10 Syringe, Luer-Lok, 10-mL equipped with 5-cm, 22-gauge needle.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of th
19、e Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.3Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.6.2 Purity of W
20、aterUnless otherwise indicated, references to water shall be understood to mean reagent water as defined byTypes II or III of Specification D1193.6.3 Ammonium Molybdate Solution(WarningPoisonous gas may be liberated in fire. Irritating to skin and eyes. Harmfulif swallowed.) (WarningIn addition to o
21、ther precautions, wear a face shield, rubber gloves, and a rubber apron when addingconcentrated sulfuric acid to water.) Using graduated cylinders for measurement, add slowly, with continuous stirring, 225 mL ofconcentrated sulfuric acid (H2SO4, relative density 1.84) to 500 mL of water contained in
22、 a beaker placed in a bath of cold water.Cool to room temperature, and add 20 g of ammonium molybdate tetrahydrate (NH4)6Mo7O244H2O). Stir until solution iscomplete and transfer to a 1000-mL flask. Dilute to the mark with water.6.4 Hydrazine Sulfate Solution Dissolve 1.5 g of hydrazine sulfate (Warn
23、ing Cancer suspect agent.) (H2NNH2H2SO4)in 1 L of water, measured with a graduated cylinder. (WarningThis solution is not stable. Keep it tightly stoppered and in thedark. Prepare a fresh solution after 3 weeks.)6.5 Molybdate-Hydrazine ReagentPipet 25 mL of ammonium molybdate solution into a 100-mL
24、volumetric flask containingapproximately 50 mL of water, add by pipet 10 mL of H2NNH2H2SO4solution, and dilute to 100 mL with water.NOTE2This 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 Phosph
25、orus, Stock Solution, Standard (1.00 mg P/mL)Dry approximately5gofpotassium dihydrogen phosphate(KH2PO4) in an oven at 105 to 110C (221 to 230F) for 3 h. Dissolve 4.393 6 0.002 g of the reagent in 150 mL, measured witha graduate cylinder, of H2SO4(1 + 10) contained in a 1000-mL volumetric flask. Dil
26、ute with water to the mark.6.7 Phosphorus Solution, Standard (10.0 g P/mL)Pipet 10 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 sulfuric acid causes severe burns. Strong oxidizer.) ( WarningI
27、naddition to other precautions, wear a face shield, rubber gloves, and a rubber apron when adding concentrated sulfuric acid towater.) Using graduated cylinders for measurement, add slowly, with continuous stirring, 100 mL of H2SO4(relative density 1.84)to 1 L of water contained in a beaker placed i
28、n a bath of cold water.6.9 Zinc Oxide(WarningSee 6.8.) (WarningHigh-bulk density zinc oxide can cause spattering. Density of approxi-mately 0.5 g/cm3has been found satisfactory.)6.10 Quality Control (QC) Samples, preferably are portions of one or more liquid petroleum materials that are stable andre
29、presentative of the samples of interest. These QC samples can be used to check the validity of the testing process as describedin Section 11.7. Sampling7.1 Take samples in accordance with the instructions in Practice D4057.7.2 Use the following table as a guide for selecting sample size:Phosphorus,m
30、g/L Equivalent, g/galSample Size,mL2.540 0.010.15 1.001.320 0.0050.075 2.000.913 0.00370.05 3.003Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar
31、Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D3231 1121 or less 0.0038 or less 10.0NOTE3When 4When using a 10-mL sample, ignite aliquots of 2 mL of sample in the
32、same 2-g portion of zinc oxide; allow the zinc oxide to coolbefore adding the next 2-mL aliquot of gasoline (Note 56).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 standard solutioninto 100-mL volumetric flasks.8.2 Pi
33、pet 10 mL of H2SO4(1 + 10) into each flask. Mix immediately by swirling.8.3 Prepare the molybdate-hydrazine reagent. Prepare sufficient volume of reagent based on the number of samples beinganalyzed.8.4 Pipet 50 mL of the molybdate-hydrazine reagent to each volumetric flask. Mix immediately by swirl
34、ing.8.5 Dilute to 100 mL with water.8.6 Mix well and place in the constant-temperature bath so that the contents of the flask are submerged below the level of thebath. Maintain bath temperature at 82.2 to 87.8C (180 to 190F) for 25 min (Note 1).8.7 Transfer the flask to the cooling bath and cool the
35、 contents rapidly to room temperature. Do not allow the samples to coolmore than 2.8C (5F) below room temperature.NOTE4Place 5Place a chemically clean thermometer in one of the flasks to check the temperature.8.8 After cooling the flasks to room temperature, remove them from the cooling water bath a
36、nd allow them to stand for 10 minat room temperature.8.9 Using the 2.0-mL phosphorus standard in a 5-cm cell, determine the wavelength near 820 nm that gives maximumabsorbance. The wavelength giving maximum absorbance should not exceed 830 nm.8.9.1 Using the red-sensitive phototube and 5-cm cells, a
37、djust the spectrophotometer to zero absorbance at the wavelength ofmaximum absorbance using distilled water. If using a dual-beam spectrophotometer, place distilled water in both cells. Use thewavelength of maximum absorbance in the determination of calibration readings and future sample readings.8.
38、9.2 The use of 1-cm cells for the higher concentrations is permissible.8.10 Measure the absorbance of each calibration sample including the blank (0.0 mL phosphorus standard) at the wavelengthof maximum absorbance with distilled water in the reference cell. Great care shall be taken to avoid possibl
39、e contamination. If theabsorbance of the blank exceeds 0.04 (for 5-cm cell), check for source of contamination. It is suggested that the results bedisregarded and the test be rerun with fresh reagents and clean glassware.8.11 Correct the absorbance of each standard solution by subtracting the absorb
40、ance of the blank (0.0 mL phosphorus standard).8.12 Prepare a calibration curve by plotting the corrected absorbance of each standard solution against micrograms ofphosphorus. One millilitre of phosphorus solution standard provides 10 g of phosphorus.9. Procedure9.1 Clean all glassware before use wi
41、th cleaning acid or by some procedure that does not involve use of commercial detergents.These compounds often contain alkali phosphates that are strongly adsorbed by glass surfaces and are not removed by ordinaryrinsing. It is desirable to segregate a special stock of glassware for use only in the
42、determination of phosphorus.9.2 Observe the usual precautions of cleanliness, careful manipulation, and avoidance of contamination in order to obtainsatisfactory accuracy with the small amounts of phosphorus involved.9.3 Transfer 2 6 0.2 g of zinc oxide into a conical pile in a clean, dry, unetched
43、ignition dish.9.4 Make a deep depression in the center of the zinc oxide pile with a stirring rod.9.5 Pipet the gasoline sample (Note 5Note 6) (see 7.2 for suggested sample volume) into the depression in the zinc oxide.(WarningIn addition to other precautions, cool the ignition dish before adding th
44、e additional aliquots of gasoline to avoid a flashfire.) Record the temperature of the fuel if the phosphorus content is required at 15.6C (60F) and make correction as directedin 10.2.NOTE5For 6For the 10-mL sample use multiple additions and a syringe. Hold the tip of the needle at approximately23 o
45、f the depth of the zincoxide layer and slowly deliver 2 mL of the sample; fast sample delivery may give low results. Give sufficient time for the gasoline to be absorbed bythe 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 burne
46、d.9.6 Cover the sample with a small amount of fresh zinc oxide from the reagent bottle (use the tip of a small spatula to deliverapproximately 0.2 g). Tap the sides of the ignition dish to pack the zinc oxide.9.7 Prepare the blank, using the same amount of zinc oxide in an ignition dish.9.8 Ignite t
47、he gasoline, using the flame from a Bunsen burner. Allow the gasoline to burn to extinction (Note 5Note 6).9.9 Place the ignition dishes containing the sample and blank in a hot muffle furnace set at a temperature of 621 to 704C (1150to 1300F) for 10 min. Remove and cool the ignition dishes. When co
48、ol gently tap the sides of the dish to loosen the zinc oxide.Again place the dishes in the muffle furnace for 5 min. Remove and cool the ignition dishes to room temperature. The abovetreatment is usually sufficient to burn the carbon. If the carbon is not completely burned off, place the dish into t
49、he furnace forfurther 5-min periods.NOTE6Step 7Step 9.9 can also be accomplished by heating the ignition dish with a Meker burner, gradually increasing the intensity of heat untilD3231 113the carbon from the sides of the dish has been burned; cool to room temperature.9.10 Pipet 25 mL of H2SO4(1 + 10) into each ignition dish. While pipeting, carefully wash all traces of zinc oxide from thesides of the ignition dish.9.11 Cover the ignition dish with a borosilicate watch glass and warm the ignition dish on a hot plate unt
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