1、Designation: D2425 04 (Reapproved 2009)Standard Test Method forHydrocarbon Types in Middle Distillates by MassSpectrometry1This standard is issued under the fixed designation D2425; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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.1. Scope1.1 This test method covers an analytical scheme using themass spectrometer to determine the hydrocarbon types
3、presentin virgin middle distillates 204 to 343C (400 to 650F) boilingrange, 5 to 95 volume % as determined by Test Method D86.Samples with average carbon number value of paraffins be-tween C12and C16and containing paraffins from C10and C18can be analyzed. Eleven hydrocarbon types are determined.Thes
4、e include: paraffins, noncondensed cycloparaffins, con-densed dicycloparaffins, condensed tricycloparaffins, alkylben-zenes, indans or tetralins, or both, CnH2n-10(indenes, etc.),naphthalenes, CnH2n-14(acenaphthenes, etc.),CnH2n-16(acenaphthylenes, etc.), and tricyclic aromatics.NOTE 1This test meth
5、od was developed on Consolidated Electrody-namics Corporation Type 103 Mass Spectrometers.1.2 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety problems, if
6、 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 regulatory limitations prior to use. For a specificwarning statement, see 10.1.2. Referenced Documents2.1 ASTM Standards:2D86
7、Test Method for Distillation of Petroleum Products atAtmospheric PressureD2549 Test Method for Separation of Representative Aro-matics and Nonaromatics Fractions of High-Boiling Oilsby Elution Chromatography3. Terminology3.1 The summation of characteristic mass fragments aredefined as follows:(71 (p
8、araffins) = total peak height of m/e+71 + 85.(67 (mono or noncondensed polycycloparaffins, orboth) = total peak height of m/e+67+68+69+81+82+83+96+97.(123 (condensed dicycloparaffins) = total peak height ofm/e+123 + 124 + 137 + 138 + etc. up to 249 + 250.(149 (condensed tricycloparaffins) = total pe
9、ak height ofm/e+149 + 150 + 163 + 164 + etc. up to 247 + 248.(91 (alkyl benzenes) = total peak height of m/e+91 + 92 + 105 + 106 + etc. up to 175 + 176.(103 (indans or tetralins, or both) = total peak height ofm/e+103 + 104 + 117 + 118 + etc. up to 187 + 188.(115 (indenes or CnH2n-10, or both) = tot
10、al peak height ofm/e+115 + 116 + 129 + 130 + etc. up to 185 + 186.128 (naphthalene) = total peak height of m/e+128.(141 (naphthalenes) = total peak height of m/e+141 + 142 + 155 + 156 + etc. up to 239 + 240.(153 (acenaphthenes or CnH2n-14, or both) = total peakheight of m/e+153 + 154 + 167 + 168 + e
11、tc. up to251 + 252.(151 (acenaphthylenes or CnH2n-16, or both) = total peakheight of m/e+151 + 152 + 165 + 166 + etc. up to249 + 250.(177 (tricyclic aromatics) = total peak height of m/e+177 + 178 + 191 + 192 + etc. up to 247 + 248.4. Summary of Test Method4.1 Samples are separated into saturate and
12、 aromatic frac-tions by Test Method D2549, and each fraction is analyzed bymass spectrometry. The analysis is based on the summation ofcharacteristic mass fragments to determine the concentration ofhydrocarbon types. The average carbon numbers of the hydro-carbon types are estimated from spectral da
13、ta. Calculations are1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0M on Mass Spectroscopy.Current edition approved Oct. 1, 2009. Published November 2009. Originallyapproved in 1965. Last pr
14、evious edition approved in 2004 as D242504. DOI:10.1520/D2425-04R09.2For 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 w
15、ebsite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.made from calibration data dependent upon the average carbonnumber of the hydrocarbon types. The results of each fractionare mathematically combined according to their mass fract
16、ionsas determined by the separation procedure. Results are ex-pressed in mass percent.NOTE 2Test Method D2549 is presently applicable only to sampleshaving 5 % points of 232C (450F) or greater.5. Significance and Use5.1 Aknowledge of the hydrocarbon composition of processstreams and petroleum produc
17、ts boiling within the range of 400to 650F (204 to 343C) is useful in following the effect ofchanges in process variables, diagnosing the source of plantupsets, and in evaluating the effect of changes in compositionon product performance properties.6. Interferences6.1 Nonhydrocarbon types, such as su
18、lfur and nitrogen-containing compounds, are not included in the matrices for thistest method. If these nonhydrocarbon types are present to anylarge extent, (for example, mass percent sulfur 0.25) they willinterfere with the spectral peaks used for the hydrocarbon-typecalculation.7. Apparatus7.1 Mass
19、 SpectrometerThe suitability of the mass spec-trometer to be used with this method of analysis shall beproven by performance tests described herein.7.2 Sample Inlet SystemAny inlet system permitting theintroduction of the sample without loss, contamination, orchange in composition. To fulfill these
20、requirements it will benecessary to maintain the system at an elevated temperature inthe range of 125 to 325C and to provide an appropriatesampling device.7.3 Microburet or Constant-Volume Pipet.8. Calibration8.1 Calibration coefficients are attached which can be useddirectly provided:8.1.1 Repeller
21、 settings are adjusted to maximize the m/e+226 ion of n-hexadecane.8.1.2 Amagnetic field is used that will permit scanning fromm/e+40 to 292.8.1.3 An ionization voltage of 70 eV and ionizing currentsin the range 10 to 70 A are used.NOTE 3The calibration coefficients were obtained for ion sourcecondi
22、tions such that the (67/(71 ratio for n-hexadecane was 0.26/1. Thecooperative study of this test method indicated an acceptable range for this( ratio between 0.2/1 to 0.30/1.NOTE 4Users of instruments other than Consolidated Electrodynam-ics Corporation Type 103 Mass Spectrometers may have to develo
23、p theirown operating parameters and calibration data.9. Performance Test9.1 Generally, mass spectrometers are in continuous opera-tion and should require no additional preparation beforeanalyzing samples. If the spectrometer has been turned on onlyrecently, it will be necessary to check its operatio
24、n in accor-dance with this method and instructions of the manufacturer toensure stability before proceeding.9.2 Mass Spectral BackgroundSamples in the carbonnumber range C10to C18should pump out so that less than0.1 % of the two largest peaks remain. For example, back-ground peaks from a saturate fr
25、action at m/e+69 and 71 shouldbe reduced to less than 0.1 % of the corresponding peaks in themixture spectrum after a normal pump out time of 2 to 5 min.10. Mass Spectrometric Procedure10.1 Obtaining the Mass Spectrum for Each Chromato-graphic FractionUsing a microburet or constant-volumepipet, intr
26、oduce sufficient sample through the inlet sample togive a pressure of 2 to 4 Pa (15 to 30 mtorr) in the inletreservoir. (WarningHydrocarbon samples of this boilingrange are combustible.) Record the mass spectrum of thesample from m/e+40 to 292 using the instrument conditionsoutlined in 8.1.1-8.1.3.1
27、1. Calculations11.1 Aromatic FractionRead peak heights from therecord mass spectrum corresponding to m/e+ratios of 67 to 69,71, 81 to 83, 85, 91, 92, 96, 97, 103 to 106, 115 to 120, 128 to134, 141 to 148, 151 to 162, 165 to 198, 203 to 212, 217 to 226,231 to 240, 245, 246, 247 to 252.Find:(71 5 71 1
28、 85 (1)(67 5 67 1 68 1 69 1 81 1 82 1 83 1 96 1 97 (2)(91 5 (N 5 0N 5 691 1 14N! 1 92 1 14N!# (3)(103 5 (N 5 0N 5 6103 1 14N! 1 104 1 14N!# (4)(115 5 (N 5 0N 5 5115 1 14N! 1 116 1 14N!# (5)(141 5 (N 5 0N 5 7141 1 14N! 1 142 1 14N!# (6)(153 5 (N 5 0N 5 7153 1 14N! 1 154 1 14N!# (7)(151 5 (N 5 0N 5 71
29、51 1 14N! 1 152 1 14N!# (8)(177 5 (N 5 0N 5 5177 1 14N! 1 178 1 14N!# (9)11.2 Calculate the mole fraction at each carbon number ofthe alkylbenzenes for n =10ton = 18 as follows:n5 Pm2 Pm21K1!#/K2(10)where:n= mole fraction of each alkylbenzene as representedby n which indicates the number of carbons
30、in eachmolecular species.m = molecular weight of the alkylbenzene being calcu-lated,m1 = molecular weight minus 1,P = polyisotopic mixture peak at m, m 1,K1= isotopic correction factor (see Table 1), andK2= mole sensitivity for n (see Table 1).NOTE 5This step of calculation assumes no mass spectral
31、patterncontributions from other hydrocarbon types to the parent and parent-1peaks of the alkylbenzenes. Selection of the lowest carbon number 10 isbased upon the fact that C9alkylbenzenes boil below 204C (400F) andtheir concentration can be considered negligible.D2425 04 (2009)211.3 Find the average
32、 carbon number of the alkylbenzenes,A, in the aromatic fraction as follows:A 5 (n 5 10n 5 18n 3 n!/(n 5 10n 5 18n! (11)11.4 Calculate the mole fraction at each carbon number ofthe naphthalenes for n =11ton = 18 as follows:xn5 Pm2 Pm21L1!#/L2(12)where:xn= mole fraction of each naphthalene as represen
33、tedby n which indicates the number of carbons ineach molecular species,m = molecular weight of the naphthalenes being cal-culated,m1 = molecular weight minus 1,P = polyisotopic mixture peak at m, m 1,L1= isotopic correction factor (see Table 1), andL2= mole sensitivity for n (see Table 1).NOTE 6This
34、 step of calculation assumes no mass spectral patterncontributions to the parent and parent-1 peaks of the naphthalenes. Theconcentration of naphthalene itself at a molecular weight of 128 shall bedetermined separately from the polyisotopic peak at m/e+128 in thematrix calculation. The average carbo
35、n number for the naphthalenes shallbe calculated from carbon number 11 (molecular weight 142) to 18(molecular weight 240).11.5 Find the average carbon number of the naphthalenes,B, in the aromatic fraction as follows:B 5 (n 5 11n 5 18nxn!/(n 5 11n 5 18xn! (13)11.6 Selection of pattern and sensitivit
36、y data for matrixcarbon number of the types present. The average carbonnumber of the paraffins and cycloparaffins (71 and (67,respectively) are related to the calculated average carbon of thealkylbenzenes (11.3), as shown in Table 2. Both (71 and (67are included in the aromatic fraction matrix to ch
37、eck onpossible overlap in the separation. The other types present,represented by (s 103, 115, 153, and 151, are usuallyrelatively low in concentration so that their parent ions areaffected by other types present. The calculation of their averagecarbon number is not straight forward. Therefore, their
38、 averagecarbon numbers are estimated by inspection of the aromaticspectrum. Generally, their average carbon numbers may betaken to be equivalent to that of the naphthalenes, or to theclosest whole number thereof, as calculated in 11.5. Theaverage carbon number of tricyclic aromatics (177 has to be a
39、tleast C14and in full boiling range middle distillates C14maybe used to represent the (177 types carbon number. From thecalculated and estimated average carbon numbers of thehydrocarbon types, a matrix for the aromatic fraction is set upusing the calibration data given in Table 3.Asample matrix fort
40、he aromatic fraction is shown in Table 4. The matrix calcula-tions consist in solving a set of simultaneous linear equations.The pattern coefficients are listed in Table 3. The constants arethe ( values determined from the mass spectrum. Secondapproximation solutions are of sufficient accuracy. If m
41、anyanalyses are performed using the same type of a matrix, thematrix may be inverted for simpler, more rapid desk calcula-tion. Matrices may also be programmed for automatic com-puter operations. The results of matrix calculations are con-verted to mass fractions by dividing by mass sensitivity. The
42、mass fractions are normalized to the mass percent of thearomatic fraction, as determined by the separation procedure.11.7 Saturate FractionRead peak at heights from therecord of the mass spectrum corresponding to m/e+ratios of 67to 69, 71, 81 to 83, 85, 91, 92, 96, 97, 105, 106, 119, 120, 123,124, 1
43、33, 134, 137, 138, 147 to 152, 161 to 166, 175 to 180,191 to 194, 205 to 208, 219 to 222, 233 to 236, 247 to 250.Find:(71 5 71 1 85 (14)(67 5 67 1 68 1 69 1 81 1 82 1 83 1 96 1 97 (15)(123 5 (N 5 0N 5 9123 1 14N! 1 124 1 14N!# (16)(149 5 (N 5 0N 5 7149 1 14N! 1 150 1 14N!# (17)(91 5 (N 5 0N 5 691 1
44、14N! 1 92 1 14N!# (18)11.8 Selection of the pattern and sensitivity data for matrixcalculation is dependent upon the average carbon number ofthe types present. The average carbon number of the paraffinsand cycloparaffin types (s 71, 69, 123, and 149), are relatedto the calculated average carbon numb
45、er of the alkylbenzenesof the aromatic fraction (11.3), as shown in Table 2. The (91is included in the saturate fraction as a check on the efficiencyof the separation procedure. The pattern and sensitivity data forthe (91 are based on the calculated or estimated averagecarbon number from the mass sp
46、ectra of the aromatic fraction(see 11.3). From the determined average carbon numbers of thehydrocarbon types, a matrix for the saturate fraction is set upTABLE 1 Parent Ion Isotope Factors and Mole SensitivitiesCarbon No. m/eIsotopeFactor, K1MoleSensitivity, K2Alkylbenzenes10 134 0.1101 8511 148 0.1
47、212 6312 162 0.1323 6013 176 0.1434 5714 190 0.1545 5415 204 0.1656 5116 218 0.1767 4817 232 0.1878 4518 246 0.1989 42L1L2Naphthalenes11 142 0.1201 19412 156 0.1314 16613 170 0.1425 15014 184 0.1536 15015 198 0.1647 15016 212 0.1758 15017 226 0.1871 15018 240 0.1982 150TABLE 2 Relationship Between A
48、verage Carbon Numbers ofAlkylbenzenes, Paraffins, and CycloparaffinsAlkylbenzenes Paraffin and CycloparaffinAverage Carbon No. Average Carbon No.10 1111 1212 1313 15(14.5)14 16(15.5)D2425 04 (2009)3TABLE 3 Patterns and Sensitivities for Middle DistillatesHydrocarbonTypeParaffins Noncondensed Cyclopa
49、raffins Condensed Dicycloparaffins Condensed TricycloparaffinsCarbon No. 12 13 14.5 15.5 12 13 14.5 15.5 13 14.5 15.5 13 14.5 15.5Peaks read:(71 100 100 100 100 446621.1.5112(67 19 21 23 26 100 100 100 100 160 130 150 175 170 150(123 . . 0.1 0.2 1 1 1 3 100 100 100 26 10 20(149 . . . . . . . . 0.2 5 8 100 100 100(91 to 176 0.4 0.4 0.4 0.4 . . 0.2 3 4 4 5 15 15 20(103 to 188 . . . . . . . . . . . 1 . 3(115 to 186 0.5 . . . 1 1 1 1 0.5 . . . . .(128 pk . . . . . . . . . . . .
