1、Designation: D1840 07 (Reapproved 2013)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 Department of Defense.1. Scope1.1 Thi
3、s 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 havingend poi
4、nts below 315C (600F); however, the range ofconcentrations used in the interlaboratory test programs whichestablished the precision statements for this test method were0.03 to 4.25 volume % for ProcedureA, and 0.08 to 5.6 volume% for Procedure B. This test method determines the maximumamount of naph
5、thalenes 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 theresponsibility of the user of
6、this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements, see 8.1 and 8.2.2. Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE169 Practices fo
7、r 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 absorp-tion spectroscopy in this test method shall confo
8、rm 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 Definitions of Terms Specific to This Standard:3.2.1 absorban
9、ce, 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 transmittance (indicated by the spectrophotometer)by comp
10、ensating 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 = absorbance defined in 3.2.1,b = sample cell path length
11、, 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 lawstates that the absorbance of a homogeneous sample containingan absorbing substance is directly proportional
12、to the concen-tration of the absorbing substance at a single wavelength,expressed byA 5 abc (3)where:1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0F on Absorption Spectrosco
13、pic Methods.Current edition approved Oct. 1, 2013. Published October 2013. Originallyapproved in 1961. Last previous edition approved in 2007 as D1840 07. DOI:10.1520/D1840-07R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
14、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1A = absorbance as defined in 3.2.1,a = absorptivity as defined in 3.
15、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 sample cell path length, b, nthe distance, incentimetres, measured in the direction of
16、 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 include thethickness of the cell in which the specimen is contained.3.2.5 transmitt
17、ance, 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 sample.4. Summary of Test Method4.1 The total concentration of naphthalenes in jet f
18、uels 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 assess the combustion characteristics ofaviation turbine fuels of the kerosene boili
19、ng 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. Interferences6.1 Interferences add to the apparent naphthalene content.Phenanthrenes,
20、dibenzothiophenes, biphenyls,benzothiophenes, and anthracenes interfere if present. The endpoint limitation of 315C will minimize this interferenceexcept for benzothiophenes and biphenyls. The contribution tomeasured naphthalene content by the presence of 1 % of suchinterfering compounds can be esti
21、mated 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 the spectral region 240 to 300 nm with a spectralslit width of 1 nm or less. Wavel
22、ength measurements shall berepeatable and known to be accurate within 0.1 nm or less asmeasured by mercury emission line at 253.65 nm or theabsorption spectrum of either holmium oxide glass at 287.5 nmor holmium oxide solution at 287.1 nm. At the 0.4 absorbancelevel in the spectral region between 24
23、0 and 300 nm, absor-bance 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 absorbance has been established by a standard-izing laboratory.7.1.1 DiscussionMany manufac
24、turers 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-photometer performance provided that they have been recali-brated periodically as recommended by
25、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 methods of testing spectrophotometers tobe used in this test method, refer to Practice E2
26、75. 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 in spectroscopicgrade isooctane for wavelength accuracy. The latter has a minor maximuma
27、t 285.7 nm. The naphthalene solution shall not be used for photometricaccuracy.7.3 Vitreous Silica Cells, two, having path lengths of 1.00 60.005 cm.7.4 Pipets, Class A.7.5 Lens Paper.7.6 Balance, capable of taring or weighing 100 g to thenearest 0.0001 g. The balance shall be accurate to 60.0002 ga
28、t a 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.Technical-grade isooctane is a satisfactory base stock for the preparationof spectroscopic solve
29、nt.Allow about 4 or 5 L of this material to percolatethrough a column of activated silica gel (74 m) 50.8 to 76.2 mm indiameter and 0.6 to 0.9 m in depth. Collect only the portion of the solventthat has a transmission compared to distilled water greater than 90 % overthe entire spectral range from 2
30、40 to 300 nm. Store in scrupulously cleanglass-stoppered bottles and always keep covered. In general it will be bestto use a fresh portion of silica gel in preparing a new batch of solvent.However the gel can be reactivated by pouring 500 mL of acetone throughthe column, draining, drying by suction,
31、 and heating the gel in thin layersin an oven at 400C until white color is restored. Activated silica gel isstored 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 inhaled), with residue after
32、evaporation no greater than 10 mg/kg.TABLE 1 Interfering CompoundsType of Interfering CompoundError in Percentage ofNaphthalenes Caused by 1 %Interfering CompoundPhenanthrenes 2Dibenzothiophenes 2Biphenyls 1Benzothiophenes 0.6Anthracenes 0.1D1840 07 (2013)2NOTE 3The 10 mg/kg is the American Chemical
33、 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 spectrophotometerwith known naphthalenes, the average absorptivity of the C10to C13naphthalenes at 285 nm can
34、be taken at 33.7 L/gcm. Thedata 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 techniques, refer to Practices E169.Check carefully sections on handling and cleaning of cells andglasswa
35、re, 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 to 15 mL of spectroscopic isooctane to aclean, dry, glass-stoppered, 25 mL volumetric flask. Weigh outapprox
36、imately1gofsample in the flask, dilute to volume withspectroscopic solvent, and mix thoroughly. If the sample is lessvolatile than isooctane, weigh out approximately1gofsamplein the flask, dilute to volume with spectroscopic solvent, andmix thoroughly.10.2.2 Second DilutionPipet 5.00 mL of the first
37、 dilutioninto a 50-mLglass-stoppered volumetric flask, dilute to volumewith spectroscopic isooctane, and mix thoroughly.10.2.3 Third DilutionDilute 5.00 mL of second dilution to50 mL in the same manner as in 10.2.2.10.3 Determination of Cell CorrectionMeasure and re-cord the absorbance of the spectr
38、oscopic isooctane-filledsample cell as compared to the spectroscopic isooctane-filledsolvent cell.10.4 Measurement of AbsorbanceTransfer portions of thefinal dilution into the sample cell of the spectrophotometer.Cover the cells immediately to prevent transfer of aromatichydrocarbons from the sample
39、 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 sample as compared tospectroscopic isooctane at 285 nm.NOTE 5The dilution of the sample should be controlled so tha
40、tabsorbance 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 specified in 10.2.3, such as 10 mLof the second dilution to 25 mL with solvent.11. Procedure BAlternative 100-mL Dilut
41、ion11.1 DiscussionThe incorporation of the single dilutionprocedure has been included as an alternative procedure toreduce: test time, glassware, cleaning, and dilution errors.11.2 For recommended techniques, refer to Practices E169.Check carefully sections on handling and cleaning of cells andglass
42、ware, instrument adjustments, and method of absorbancemeasurement.11.3 Sample PreparationAdd an appropriate weight ofsample to a clean, dry, tared 100-mL volumetric flask. Recordthe weight to the nearest 0.0001 g. Dilute to the mark withspectroscopic grade isooctane, stopper, and mix thoroughly.11.3
43、.1 Refer to Table 3 for lists of sample weights associ-ated with naphthalene(s) concentrations that give 0.2 to 0.8absorbance readings as directed in Note 7. A 60-mg samplewill be appropriate for typical jet fuels in the range of 0.8 to3.0 % volume naphthalenes.NOTE 6A micropipette is a convenient t
44、ool 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 writtenin 10.3.11.5 Measurement of AbsorbanceProceed as written in10.4.12. Calculations12.1 Calculate the mass percentag
45、e of naphthalenes in thesample as follows:Naphthalenes, mass% 5 A 3 K!/33.7 3 W!# 3100 (5)where:A = corrected absorbance (observed absorbance minus cellcorrection) of the dilution measured,For Procedure A in Section 10 using serial dilutions,TABLE 2 Data Issued by API Research Project 44CompoundAPI
46、SerialNumberL/gcmNaphthalene 605 28.51-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-dim
47、ethyl Naphthalene 221 46.02,3-dimethyl Naphthalene 222 22.02,6-dimethyl Naphthalene 226 21.32,7-dimethyl Naphthalene 224 23.51-isopropyl Naphthalene 203 31.7TABLE 3 Estimated Sample Weight and Volume to Take for theVolume % Naphthalene Content of the Sample in the SingleDilution Procedure to Keep th
48、e Absorption Values Between 0.2and 0.8 Units (Assuming a Density of 0.8)SampleVolume(mL)SampleWeight(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 1.60.200 160 0.3 1.20.30
49、0 240 0.2 0.8D1840 07 (2013)3K = equivalent volume of solvent, in litres, if the dilutionhad been made in a single step. For the first dilutionK = 0.025, for the second dilution K = 0.25, for the thirddilution K = 2.5. For the suggested alternative thirddilution K = 0.625,For Procedure B in Section 11 using 100-mL dilution,K = 0.10,W = grams of sample used, and33.7 = the average absorptivity of C10to C13naphthalenes inlitres per gram-centimetre.12.2 Calculate the volume percentage of naphthalenes asfollows:Naphthalenes, volume% 5 M 3 B/C
