1、Designation: D1840 07 (Reapproved 2017)Standard Test Method forNaphthalene Hydrocarbons in Aviation Turbine Fuels byUltraviolet Spectrophotometry1This standard is issued under the fixed designation D1840; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number 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 U.S. Department of Defense.1. Scope1.
3、1 This test method covers the determination, by ultravioletspectrophotometry, of the total concentration of naphthalene,acenaphthene, and alkylated derivatives of these hydrocarbonsin jet fuels. This test method is designed to analyze fuelscontaining not more than 5 % of such components and havingen
4、d points below 315 C (600 F); however, the range ofconcentrations used in the interlaboratory test programs whichestablished the precision statements for this test method were0.03 % to 4.25 % by volume for Procedure A, and 0.08 % to5.6 % by volume for Procedure B. This test method determinesthe maxi
5、mum amount of naphthalenes that could be present.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibili
6、ty of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific warning statements, see 8.1 and 8.2.1.4 This international standard was developed in accor-dance with internation
7、ally recognized principles on standard-ization established in the Decision on Principles for 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:2E131 Termin
8、ology Relating to Molecular SpectroscopyE169 Practices for General Techniques of Ultraviolet-VisibleQuantitative AnalysisE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers3. Terminology3.1 Definitions:3.1.1 Definitions of terms and symbols relating to
9、 absorp-tion spectroscopy in this test method shall conform to Termi-nology E131. Terms of particular significance are the follow-ing:3.1.2 radiant energy, nenergy transmitted as electromag-netic waves.3.1.3 radiant power, P, nrate at which energy is trans-ported in a beam of radiant energy.3.2 Defi
10、nitions of Terms Specific to This Standard:3.2.1 absorbance, A, nthe molecular property of a sub-stance that determines its ability to take up radiant power,expressed byA 5 log101/T! 52log10T (1)where:T = transmittance as defined in 3.2.5.3.2.1.1 DiscussionIt may be necessary to correct theobserved
11、transmittance (indicated by the spectrophotometer)by compensating for reflectance losses, solvent absorptionlosses, or refraction effects.3.2.2 absorptivity, a, nthe specific property of a substanceto absorb radiant power per unit sample concentration and pathlength, expressed bya 5 A/bc (2)where:A
12、= absorbance defined in 3.2.1,b = sample cell path length, andc = quantity of absorbing substance contained in a unitvolume of solvent.3.2.2.1 DiscussionQuantitative ultraviolet analyses arebased upon the absorption law, known as Beers law. The law1This test method is under the jurisdiction of ASTM
13、Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0F on Absorption Spectroscopic Methods.Current edition approved Oct. 1, 2017. Published November 2017. Originallyapproved in 1961. Last previous edition approved in 2013 as D1840 0
14、7 (2013).DOI: 10.1520/D1840-07R17.2For 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.Copyright ASTM Internationa
15、l, 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 the Decision on Principles for theDevelopment of International Standards, Guides
16、and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1states that the absorbance of a homogeneous sample containingan absorbing substance is directly proportional to the concen-tration of the absorbing substance at a single wavelength,expressed byA 5
17、 abc (3)where:A = absorbance as defined in 3.2.1,a = absorptivity as defined in 3.2.2,b = sample cell path length, andc = quantity of absorbing substance contained in a unitvolume of solvent.3.2.3 concentration, c, nthe quantity of naphthalene hy-drocarbons in grams per litre of isooctane.3.2.4 samp
18、le cell path length, b, nthe distance, incentimetres, measured in the direction of propagation of thebeam of radiant energy, between the surfaces of the specimenon which the radiant energy is incident and the surface of thespecimen from which it is emergent.3.2.4.1 DiscussionThis distance does not i
19、nclude thethickness of the cell in which the specimen is contained.3.2.5 transmittance, T, nthe molecular property of a sub-stance that determines its transportability of radiant powerexpressed byT 5 P/Po(4)where:P = radiant power passing through the sample, andPo= radiant power incident upon the sa
20、mple.4. Summary of Test Method4.1 The total concentration of naphthalenes in jet fuels isdetermined by measurement of the absorbance at 285 nm of asolution of the fuel at known concentration.5. Significance and Use5.1 This test method for naphthalene hydrocarbons is one ofa group of tests used to as
21、sess the combustion characteristics ofaviation turbine fuels of the kerosene boiling range. Thenaphthalene hydrocarbon content is determined becausenaphthalenes, when burned, tend to have a relatively largercontribution to a sooty flame, smoke, and thermal radiationthan single ring aromatics.6. Inte
22、rferences6.1 Interferences add to the apparent naphthalene content.Phenanthrenes, dibenzothiophenes, biphenyls,benzothiophenes, and anthracenes interfere if present. The endpoint limitation of 315 C will minimize this interferenceexcept for benzothiophenes and biphenyls. The contribution tomeasured
23、naphthalene content by the presence of 1 % of suchinterfering compounds can be estimated from Table 1.6.2 Saturated hydrocarbons, olefins, thiophenes, and alkylor cycloalkyl derivatives of benzene will not interfere.7. Apparatus7.1 Spectrophotometer, equipped to measure the absorbanceof solutions in
24、 the spectral region 240 nm to 300 nm with aspectral slit width of 1 nm or less. Wavelength measurementsshall be repeatable and known to be accurate within 0.1 nm orless as measured by mercury emission line at 253.65 nm or theabsorption spectrum of either holmium oxide glass at 287.5 nmor holmium ox
25、ide solution at 287.1 nm. At the 0.4 absorbancelevel in the spectral region between 240 nm and 300 nm, ab-sorbance measurements shall be repeatable within 60.5 % orbetter. In the absorbance range encompassing 0.2 to 0.8, thephotometric accuracy shall not differ by more than 60.5 % ofsamples whose ab
26、sorbance has been established by a standard-izing laboratory.7.1.1 DiscussionMany manufacturers provide secondarystandards, traceable to NIST primary standards, for checkingthe wavelength accuracy and photometric accuracy of spectro-photometers. These materials may be used to verify spectro-photomet
27、er performance provided that they have been recali-brated periodically as recommended by the manufacturer.7.2 It shall be initially and thereafter periodically demon-strated that an instrument can be operated in a manner to givetest results equivalent to those described in 7.1.NOTE 1For recommended
28、methods of testing spectrophotometers tobe used in this test method, refer to Practice E275. Other preferredalternatives to those in 7.1 are potassium dichromate in perchloric acid(NIST SRM 935 series as described in Practice E275) for photometricaccuracy and a 20 mg L high (99 %) purity naphthalene
29、 in spectroscopicgrade isooctane for wavelength accuracy. The latter has a minor maximumat 285.7 nm. The naphthalene solution shall not be used for photometricaccuracy.7.3 Vitreous Silica Cells, two, having path lengths of1.00 cm 6 0.005 cm.7.4 Pipets, Class A.7.5 Lens Paper.7.6 Balance, capable of
30、taring or weighing 100 g to thenearest 0.0001 g. The balance shall be accurate to 60.0002 g ata 100 g load.8. Solvents8.1 Spectroscopic 2,2,4 Trimethylpentane (Isooctane).(WarningIsooctane is extremely flammable, harmful if in-haled.)NOTE 2Spectroscopic-grade isooctane is available commercially.Tech
31、nical-grade isooctane is a satisfactory base stock for the preparationof spectroscopic solvent. Allow about 4 L or 5 L of this material topercolate through a column of activated silica gel (74 m) 50.8 mm to76.2 mm in diameter and 0.6 m to 0.9 m in depth. Collect only the portionof the solvent that h
32、as a transmission compared to distilled water greaterthan 90 % over the entire spectral range from 240 nm to 300 nm. Store inscrupulously clean glass-stoppered bottles and always keep covered. Ingeneral it will be best to use a fresh portion of silica gel in preparing a newTABLE 1 Interfering Compou
33、ndsType of Interfering CompoundError in Percentage ofNaphthalenes Caused by 1 %Interfering CompoundPhenanthrenes 2Dibenzothiophenes 2Biphenyls 1Benzothiophenes 0.6Anthracenes 0.1D1840 07 (2017)2batch of solvent. However the gel can be reactivated by pouring 500 mLof acetone through the column, drain
34、ing, drying by suction, and heatingthe gel in thin layers in an oven at 400 C until white color is restored.Activated silica gel is stored in closed containers.8.2 Solvents for Cleaning CellsAcetone or ethyl alcohol(WarningAcetone and ethyl alcohol are extremely flam-mable and can be harmful if inha
35、led), with residue afterevaporation no greater than 10 mg kg.NOTE 3The 10 mg kg is the American Chemical Society (ACS)reagent grade maximum specification. An ACS reagent grade solvent maybe used without further testing.9. Calibration and Standardization9.1 Instead of direct calibration of the spectr
36、ophotometerwith known naphthalenes, the average absorptivity of the C10to C13naphthalenes at 285 nm can be taken at 33.7 L gcm.The data used to calculate this average are given in Table 2.10. Procedure ASerial DilutionNOTE 4The user may use alternative Procedure B if preferred.10.1 For recommended t
37、echniques, refer to Practices E169.Check carefully sections on handling and cleaning of cells andglassware, instrument adjustments, and method of absorbancemeasurement.10.2 Prepare three dilutions of the sample as follows:10.2.1 First DilutionIf the sample is more volatile thanisooctane, add 10 mL t
38、o 15 mL of spectroscopic isooctane to aclean, dry, glass-stoppered, 25 mL volumetric flask. Weigh outapproximately 1 g of sample in the flask, dilute to volume withspectroscopic solvent, and mix thoroughly. If the sample is lessvolatile than isooctane, weigh out approximately 1 g of samplein the fla
39、sk, dilute to volume with spectroscopic solvent, andmix thoroughly.10.2.2 Second DilutionPipet 5.00 mL of the first dilutioninto a 50 mL glass-stoppered volumetric flask, dilute to volumewith spectroscopic isooctane, and mix thoroughly.10.2.3 Third DilutionDilute 5.00 mL of second dilution to50 mL i
40、n the same manner as in 10.2.2.10.3 Determination of Cell CorrectionMeasure and re-cord the absorbance of the spectroscopic isooctane-filledsample cell as compared to the spectroscopic isooctane-filledsolvent cell.10.4 Measurement of AbsorbanceTransfer portions of thefinal dilution into the sample c
41、ell of the spectrophotometer.Cover the cells immediately to prevent transfer of aromatichydrocarbons from the sample cell to the solvent cell. Checkthe windows of the absorption cells and make certain they areclean. Measure the absorbance as recommended in PracticesE169. Record the absorbance of the
42、 sample as compared tospectroscopic isooctane at 285 nm.NOTE 5The dilution of the sample should be controlled so thatabsorbance readings fall within a range of 0.2 to 0.8 for maximumreproducibility of results. To accomplish this it may be necessary to use analternative third dilution than the one sp
43、ecified in 10.2.3, such as 10 mLof the second dilution to 25 mL with solvent.11. Procedure BAlternative 100 mL Dilution11.1 DiscussionThe incorporation of the single dilutionprocedure has been included as an alternative procedure toreduce: test time, glassware, cleaning, and dilution errors.11.2 For
44、 recommended techniques, refer to Practices E169.Check carefully sections on handling and cleaning of cells andglassware, instrument adjustments, and method of absorbancemeasurement.11.3 Sample PreparationAdd an appropriate mass ofsample to a clean, dry, tared 100 mL volumetric flask. Recordthe mass
45、 to the nearest 0.0001 g. Dilute to the mark withspectroscopic grade isooctane, stopper, and mix thoroughly.11.3.1 Refer to Table 3 for lists of sample masses associatedwith naphthalene(s) concentrations that give 0.2 to 0.8 absor-bance readings as directed in Note 7. A 60 mg sample will beappropria
46、te for typical jet fuels in the range of 0.8 % to 3.0 %by volume naphthalenes.NOTE 6A micropipette is a convenient tool for adding an appropriatevolume. If the fuel density is not known at the time of sample preparation,use 0.8 as an approximation.11.4 Determination of Cell CorrectionProceed as writ
47、tenin 10.3.11.5 Measurement of AbsorbanceProceed as written in10.4.12. Calculations12.1 Calculate the mass percentage of naphthalenes in thesample as follows:Naphthalenes, mass% 5 A 3K!/33.7 3W!# 3100 (5)TABLE 2 Data Issued by API Research Project 44CompoundAPI SerialNumberL/gcmNaphthalene 605 28.51
48、-methyl Naphthalene 539 32.02-methyl Naphthalene 572 22.91,2-dimethyl Naphthalene 215 37.31,3-dimethyl Naphthalene 216 36.41,4-dimethyl Naphthalene 217 43.51,5-dimethyl Naphthalene 218 54.01,6-dimethyl Naphthalene 219 36.41,7-dimethyl Naphthalene 220 36.01,8-dimethyl Naphthalene 221 46.02,3-dimethyl
49、 Naphthalene 222 22.02,6-dimethyl Naphthalene 226 21.32,7-dimethyl Naphthalene 224 23.51-isopropyl Naphthalene 203 31.7TABLE 3 Estimated Sample Mass and Volume to Take for theVolume % Naphthalene Content of the Sample in the SingleDilution Procedure to Keep the Absorption Values Between 0.2and 0.8 Units (Assuming a Density of 0.8)SampleVolume(mL)SampleMass(mg)Volume % Naphthalenesfor ExpectedAbsorbanceof 0.2 unitsVolume % Naphthalenesfor ExpectedAbsorbanceof 0.8 units0.050 40 1.2 4.80.075 60 0.8 3.20.100 80 0.6 2.40.150 120 0.4 1.60.200
