1、Designation: D 1840 03An American National StandardStandard Test Method forNaphthalene Hydrocarbons in Aviation Turbine Fuels byUltraviolet Spectrophotometry1This standard is issued under the fixed designation D 1840; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. 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
3、. Scope*1.1 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 an
4、d havingend points 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 maximu
5、mamount of naphthalenes that could be present.1.2 The values stated in SI units are to be regarded as thestandard. The values stated in inch-pound units are for infor-mation only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespon
6、sibility 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. For specificwarning statements, see 8.1 and 8.2.2. Referenced Documents2.1 ASTM Standards:2E 131 Terminology Relating to Molecular Spec
7、troscopyE 169 Practices for General Techniques of Ultraviolet-Visible Quantitative AnalysisE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-eters3. Terminology3.1 Definitions:3.1.1 Definitions of terms and symbols relating to absorp-tion
8、 spectroscopy in this test method shall conform to Termi-nology E 131. Terms of particular significance are the follow-ing:3.1.1.1 radiant energy, nenergy transmitted as electro-magnetic waves.3.1.1.2 radiant power, P, nthe rate at which energy istransported in a beam of radiant energy.3.2 Definitio
9、ns 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 trans
10、mittance (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 = abs
11、orbance 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 lawstates that the absorbance of a homogeneous sample contai
12、ning1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0F on Absorption Spectroscopic Methods.Current edition approved Nov. 1, 2003. Published November 2003. Originallyapproved in 1961. Last pre
13、vious edition approved in 2002 as D 1840-02.2For 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 Ch
14、anges 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.an absorbing substance is directly proportional to the concen-tration of the absorbing substance at a single wavelength,expressed byA 5
15、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 sampl
16、e cell path length, b, nthe distance, in centi-metres, measured in the direction of propagation of the beam ofradiant energy, between the surfaces of the specimen on whichthe radiant energy is incident and the surface of the specimenfrom which it is emergent.3.2.4.1 DiscussionThis distance does not
17、include thethickness of the cell in which the specimen is contained.3.2.5 transmittance, T, nthe molecular property of asubstance 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 sam
18、ple.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 ass
19、ess the combustion characteristics ofaviation turbine fuels of the kerosene boiling range. Thenaphthalene hydrocarbon content is determined because naph-thalenes, when burned, tend to have a relatively larger contri-bution to a sooty flame, smoke, and thermal radiation thansingle ring aromatics.6. I
20、nterferences6.1 Interferences add to the apparent naphthalene content.Phenanthrenes, dibenzothiophenes, biphenyls, ben-zothiophenes, and anthracenes interfere if present. The endpoint limitation of 315C will minimize this interferenceexcept for benzothiophenes and biphenyls. The contribution tomeasu
21、red 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 solution
22、s in the spectral region 240 to 300 nm with a spectralslit width of 1 nm or less. Wavelength 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 o
23、xide solution at 287.1 nm. At the 0.4 absorbancelevel in the spectral region between 240 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 abso
24、rbance 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-photometer
25、 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 me
26、thods of testing spectrophotometers tobe used in this test method, refer to Practice E 275. Other preferredalternatives to those in 7.1 are potassium dichromate in perchloric acid(NIST SRM 935 series as described in Practice E 275) for photometricaccuracy and a 20 mg/L high (99 %) purity naphthalene
27、 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 of 1.00 60.005 cm.7.4 Pipets, Class A.7.5 Lens Paper.7.6 Balance, capable of tar
28、ing or weighing 100 g to thenearest 0.0001 g. The balance shall be accurate to 60.0002 gat 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.Technic
29、al-grade isooctane is a satisfactory base stock for the preparationof spectroscopic solvent.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 transm
30、ission compared to distilled water greater than 90 % overthe entire spectral range from 240 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
31、 reactivated by pouring 500 mL of acetone throughthe column, draining, drying by suction, and heating the gel in thin layersin an oven at 400C until white color is restored. Activated silica gel isstored in closed containers.TABLE 1 Interfering CompoundsType of Interfering CompoundError in Percentag
32、e ofNaphthalenes Caused by 1 %Interfering CompoundPhenanthrenes 2Dibenzothiophenes 2Biphenyls 1Benzothiophenes 0.6Anthracenes 0.1D18400328.2 Solvents for Cleaning CellsAcetone or ethyl alcohol(WarningAcetone and ethyl alcohol are extremely flam-mable and can be harmful if inhaled), with residue afte
33、revaporation 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 spectrophotometerwith known n
34、aphthalenes, the average absorptivity of the C10to C13naphthalenes at 285 nm can 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 Pra
35、ctices E 169.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 to 15 mL of spectroscopic
36、isooctane to aclean, dry, glass-stoppered, 25 mL volumetric flask. Weigh outapproximately1gofsample 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 spectro
37、scopic solvent, andmix thoroughly.10.2.2 Second DilutionPipet 5.00 mL of the first 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.
38、3 Determination of Cell CorrectionMeasure andrecord 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 cell of the spectrophotometer.Cover t
39、he 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 PracticesE 169. Record the absorbance of the sample as compared tospectroscopic
40、 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 specified in 10.2.3, such as 10 mLof
41、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 recommended techniques, refer to P
42、ractices E 169.Check carefully sections on handling and cleaning of cells andglassware, 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. Dilu
43、te to the mark withspectroscopic grade isooctane, stopper, and mix thoroughly.11.3.1 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 t
44、he range of 0.8 to3.0 % 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 writtenin 10.3.11.5 Measurement of Abs
45、orbanceProceed as written in10.4.12. Calculations12.1 Calculate the mass percentage of naphthalenes in thesample as follows:Naphthalenes, mass % 5 AK/33.7W! 3 100 (5)where:A = corrected absorbance (observed absorbance minus cellcorrection) of the dilution measured,TABLE 2 Data Issued by API Research
46、 Project 44CompoundAPI 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 Naph
47、thalene 220 36.01,8-dimethyl 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 SingleDiluti
48、on Procedure to Keep the Absorption Values Between 0.2and 0.8 Units (Assuming a Density of 0.8)SampleVolume(mL)SampleWeight(mg)Volume % Naphthalenesfor Expected Absorbanceof 0.2 unitsVolume % Naphthalenesfor Expected Absorbanceof 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
49、 1.60.200 160 0.3 1.20.300 240 0.2 0.8D1840033For Procedure A in Section 10 using serial dilutions,K = 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 thethird dilution K = 2.5. For the suggested alternativethird dilution 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 C13naphthalenesin litres per gram-centimetre.12.2 Calculate the volume percen
