ASTM D2425-99
(Test Method)Standard Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
Standard Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
SCOPE
1.1 This test method covers an analytical scheme using the mass spectrometer to determine the hydrocarbon types present in virgin middle distillates 204 to 343°C (400 to 650°F) boiling range, 5 to 95 volume% as determined by Method D86. Samples with average carbon number value of paraffins between C 12 and C 16 and containing paraffins from C 10 and C 18 can be analyzed. Eleven hydrocarbon types are determined. These include:paraffins, noncondensed cycloparaffins, condensed dicycloparaffins, condensed tricycloparaffins, alkylbenzenes, indans or tetralins, or both, CnH n- 10 (indenes, etc.), naphthalenes, CnH n- 14 (acenaphthenes, etc.), CnH n- 16 (acenaphthylenes, etc.), and tricyclic aromatics. Note 1-This test method was developed on consolidated Electrodynamics Corp. Type 103 Mass Spectrometers.
1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see 10.1.
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An American National Standard
Designation:D2425–99
Standard Test Method for
Hydrocarbon Types in Middle Distillates by Mass
Spectrometry
This standard is issued under the fixed designation D2425; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 The summation of characteristic mass fragments are
defined as follows:
1.1 This test method covers an analytical scheme using the
+
3.2 (71 (paraffins)=total peak height of m/e 71 + 85.
mass spectrometer to determine the hydrocarbon types present
3.3 (67 (mono or noncondensed polycycloparaffins, or
invirginmiddledistillates204to343°C(400to650°F)boiling
+
both) = total peak height of m/e
range, 5 to 95 volume% as determined by Test Method D86.
67+68+69+81+82+83+96+97.
Samples with average carbon number value of paraffins be-
3.4 (123 (condensed dicycloparaffins)=total peak height
tween C and C and containing paraffins from C and C
12 16 10 18
+
of m/e 123+124+137+138+··· etc. up to 249+250.
can be analyzed. Eleven hydrocarbon types are determined.
3.5 (149 (condensed tricycloparaffins)=total peak height
These include: paraffins, noncondensed cycloparaffins, con-
+
of m/e 149+150+163+164+··· etc. up to 247+248.
densed dicycloparaffins, condensed tricycloparaffins, alkylben-
+
3.6 (91 (alkyl benzenes) = total peak height of m/e
zenes, indans or tetralins, or both, C H (indenes, etc.),
n 2n-10
91+92+105+106+··· etc. up to 175+176.
naphthalenes, C H (acenaphthenes, etc.), C H
n 2n -14 n 2n-
3.7 (103 (indans or tetralins, or both)=total peak height of
16(acenaphthylenes, etc.), and tricyclic aromatics.
+
m/e 103+104+117+118+··· etc. up to 187+188.
NOTE 1—This test method was developed on consolidated Electro-
3.8 (115 (indenes or C H , or both)=total peak height
n 2n-10
dynamics Corp. Type 103 Mass Spectrometers.
+
of m/e 115+116+129+130+··· etc. up to 185+186.
+
1.2 The values stated in SI units are to be regarded as the
3.9 128 (naphthalene)=total peak height of m/e 128.
+
standard. The inch-pound units given in parentheses are for
3.10 (141 (naphthalenes) = total peak height of m/e
information only.
141+142+155+156+··· etc. up to 239+240.
1.3 This standard does not purport to address all of the
3.11 (153 (acenaphthenes or C H , or both)=total
n 2n-14
+
safety problems, if any, associated with its use. It is the
peak height of m/e 153+154+167+168+··· etc. up to
responsibility of the user of this standard to establish appro-
251+252.
priate safety and health practices and determine the applica-
3.12 (151 (acenaphthylenes or C H , or both)=total
n 2n-16
+
bility of regulatory limitations prior to use. For a specific
peak height of m/e 151+152+165+166+··· etc. up to
hazard statement, see 10.1.
249+250.
+
3.13 (177 (tricyclic aromatics)=total peak height of m/e
2. Referenced Documents
177+178+191+192+··· etc. up to 247+248.
2.1 ASTM Standards:
4. Summary of Test Method
D86 Test Method for Distillation of Petroleum Products
D2549 Test Method for Separation of Representative Aro-
4.1 Samples are separated into saturate and aromatic frac-
matics and Nonaromatics Fractions of High-Boiling Oils
tions byTest Method D2549, and each fraction is analyzed by
by Elution Chromatography
mass spectrometry. The analysis is based on the summation of
characteristicmassfragmentstodeterminetheconcentrationof
3. Terminology
hydrocarbon types. The average carbon numbers of the hydro-
3.1 Descriptions of Terms Specific to This Standard;
carbon types are estimated from spectral data. Calculations are
madefromcalibrationdatadependentupontheaveragecarbon
number of the hydrocarbon types. The results of each fraction
This test method is under the jurisdiction of ASTM Committee D-2 on
are mathematically combined according to their mass fractions
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
as determined by the separation procedure. Results are ex-
D02.04 on Hydrocarbon Analyses.
Current edition approved April 10, 1999. Published June 1999. Originally
pressed in mass percent.
published as D2425–65T. Last previous edition D2425–93.
Annual Book of ASTM Standards, Vol 05.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2425–99
NOTE 2—Test Method D2549, is presently applicable only to samples
bereducedtolessthan0.1%ofthecorrespondingpeaksinthe
having 5% points of 232°C (450°F) or greater.
mixture spectrum after a normal pump out time of 2 to 5 min.
5. Significance and Use 10. Mass Spectrometric Procedure
5.1 Aknowledgeofthehydrocarboncompositionofprocess 10.1 Obtaining the Mass Spectrum for Each Chromato-
streamsandpetroleumproductsboilingwithintherangeof400 graphic Fraction—Using a microburet or constant-volume
to 650°F (204 to 343°C) is useful in following the effect of pipet, introduce sufficient sample through the inlet sample to
changes in process variables, diagnosing the source of plant give a pressure of 2 to 4 Pa (15 to 30 mtorr) in the inlet
upsets, and in evaluating the effect of changes in composition reservoir. (Warning—See Note 5.) Record the mass spectrum
+
on product performance properties. of the sample from m/e 40 to 292 using the instrument
conditions outlined in 8.1.1-8.1.3.
6. Interferences
NOTE 5—Warning:Hydrocarbon samples of this boiling range are
6.1 Nonhydrocarbon types, such as sulfur and nitrogen-
combustible.
containingcompounds,arenotincludedinthematricesforthis
11. Calculations
method.Ifthesenonhydrocarbontypesarepresenttoanylarge
extent, (for example, mass percent sulfur > 0.25) they will 11.1 Aromatic Fraction—Read peak heights from the
+
interfere with the spectral peaks used for the hydrocarbon-type recordmassspectrumcorrespondingtom/e ratiosof67to69,
calculation. 71, 81 to 83, 85, 91, 92, 96, 97, 103 to 106, 115 to 120, 128 to
134,141to148,151to162,165to198,203to212,217to226,
7. Apparatus
231 to 240, 245, 246, 247 to 252.
Find:
7.1 Mass Spectrometer—The suitability of the mass spec-
trometer to be used with this method of analysis shall be
(71 571 185, (1)
proven by performance tests described herein.
(67 567 168 181 182 183 196 197, (2)
7.2 Sample Inlet System—Any inlet system permitting the
N 56
(91 5 ( [~91 114N! 1 ~92 114N!], (3)
N 50
introduction of the sample without loss, contamination, or
N 56
change in composition. To fulfill these requirements it will be
(103 5 ( , (4)
N 50
necessary to maintain the system at an elevated temperature in
N 55
(115 5 ( , (5)
N 50
the range of 125 to 325°C and to provide an appropriate
N 57
(141 5 ( , (6)
sampling device. N 50
N 57
7.3 Microburet or Constant-Volume Pipet.
(153 5 ( , (7)
N 50
N 57
(151 5 ( , (8)
N 50
8. Calibration
and
8.1 Calibration coefficients are attached which can be used
N 55
directly provided:
(177 5 ( [~177 114N! 1 ~178 114N!]. (9)
N 50
+
8.1.1 Repeller settings are adjusted to maximize the m/e
226 ion of n-hexadecane.
11.2 Calculate the mole fraction at each carbon number of
8.1.2 Amagneticfieldisusedthatwillpermitscanningfrom
the alkylbenzenes for n=10to n=18 as follows:
+
m/e 40 to 292.
µ 5[P 2 P ~K !]/K (10)
n m m21 1 2
8.1.3 An ionization voltage of 70 eV and ionizing currents
in the range 10 to 70 µA are used.
where:
µ = mole fraction of each alkylbenzene as represented
NOTE 3—The calibration coefficients were obtained for ion source n
bynwhichindicatesthenumberofcarbonsineach
conditions such that the (67/(71 ratio for n-hexadecane was 0.26/1. The
cooperativestudyofthistestmethodindicatedanacceptablerangeforthis molecular species.
( ratio between 0.2/1 to 0.30/1.
m = molecular weight of the alkylbenzene being calcu-
NOTE 4—Users of instruments other than Consolidated Electrodynam-
lated,
ics Corp. Type 103 Mass Spectrometers may have to develop their own
m−1 = molecular weight minus 1,
operating parameters and calibration data.
P = polyisotopic mixture peak at m, m−1,
K = isotopic correction factor (see Table 1), and
9. Performance Test
K = mole sensitivity for n (see Table 1).
9.1 Generally, mass spectrometers are in continuous opera-
tion and should require no additional preparation before
NOTE 6—This step of calculation assumes no mass spectral pattern
analyzingsamples.Ifthespectrometerhasbeenturnedononly
contributions from other hydrocarbon types to the parent and parent-1
recently, it will be necessary to check its operation in accor-
peaks of the alkylbenzenes. Selection of the lowest carbon number 10 is
dance with this method and instructions of the manufacturer to
based upon the fact that C alkylbenzenes boil below 204°C (400°F) and
ensure stability before proceeding.
their concentration can be considered negligible.
9.2 Mass Spectral Background—Samples in the carbon
11.3 Find the average carbon number of the alkylbenzenes,
number range C to C should pump out so that less than
10 18
A, in the aromatic fraction as follows:
0.1% of the two largest peaks remain. For example, back-
+ n 518 n 518
ground peaks from a saturate fraction at m/e 69 and 71 should A 5 ~( n 3 µ !/~( µ ! (11)
n 510 n n 510 n
D2425–99
TABLE 1 Parent Ion Isotope Factors and Mole Sensitivities TABLE 2 Relationship Between Average Carbon Numbers of
Alkylbenzenes, Paraffins, and Cycloparaffins
Isotope
Mole
Carbon No. m/e Factor,
Alkylbenzenes Paraffin and Cycloparaffin
Sensitivity, K
K
Average Average
Alkylbenzenes
Carbon No. Carbon No.
10 134 0.1101 85
10 11
11 148 0.1212 63
11 12
12 162 0.1323 60
12 13
13 176 0.1434 57
13 15(14.5)
14 190 0.1545 54
14 16(15.5)
15 204 0.1656 51
16 218 0.1767 48
17 232 0.1878 45
18 246 0.1989 42
taken to be equivalent to that of the naphthalenes, or to the
L L
1 2
closest whole number thereof, as calculated in 11.5. The
Naphthalenes
averagecarbonnumberoftricyclicaromatics (177hastobeat
11 142 0.1201 194
least C and in full boiling range middle distillates C may
12 156 0.1314 166 14 14
13 170 0.1425 150 be used to represent the (177 types carbon number. From the
14 184 0.1536 150
calculated and estimated average carbon numbers of the
15 198 0.1647 150
hydrocarbon types, a matrix for the aromatic fraction is set up
16 212 0.1758 150
17 226 0.1871 150
usingthecalibrationdatagiveninTable3.Asamplematrixfor
18 240 0.1982 150
the 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 are
11.4 Calculate the mole fraction at each carbon number of
the ( values determined from the mass spectrum. Second
the naphthalenes for n=11to n=18 as follows:
approximation solutions are of sufficient accuracy. If many
x 5[P 2 P ~L !]/L (12)
analyses are performed using the same type of a matrix, the
n m m21 1 2
matrix may be inverted for simpler, more rapid desk calcula-
where:
tion. Matrices may also be programmed for automatic com-
x = mole fraction of each naphthalene as represented
n
puter operations. The results of matrix calculations are con-
by n which indicates the number of carbons in
verted to mass fractions by dividing by mass sensitivity. The
each molecular species,
mass fractions are normalized to the mass percent of the
m = molecular weight of the naphthalenes being cal-
aromatic fraction, as determined by the separation procedure.
culated,
11.7 Saturate Fraction—Read peak at heights from the
m−1 = molecular weight minus 1,
+
recordofthemassspectrumcorrespondingto m/e ratiosof67
P = polyisotopic mixture peak at m, m−1,
to 69, 71, 81 to 83, 85, 91, 92, 96, 97, 105, 106, 119, 120, 123,
L = isotopic correction factor (see Table 1), and
124, 133, 134, 137, 138, 147 to 152, 161 to 166, 175 to 180,
L = mole sensitivity for n (see Table 1).
191 to 194, 205 to 208, 219 to 222, 233 to 236, 247 to 250.
NOTE 7—This step of calculation assumes no mass spectral pattern
Find:
contributions to the parent and parent-1 peaks of the naphthalenes. The
(71 571 185, (14)
concentration of naphthalene itself at a molecular weight of 128 shall be
+
determined separately from the polyisotopic peak at m/e 128 in the
(67 567 168 169 181 182 183 196 197, (15)
matrix calculation. The average carbon number for the naphthalenes shall
N 59
(123 5 ( , (16)
be calculated from carbon number 11 (molecular weight 142) to 18 N 50
(molecular weight 240). N 57
(149 5 ( , (17)
N 50
11.5 Find the average carbon number of the naphthalenes,
N 56
(91 5 ( [ 91 114N! 1 92 114N!]. (18)
~ ~
N 50
B, in the aromatic fraction as follows:
11.8 Selection of the pattern and sensitivity data for matrix
n 518 n 518
B 5 ( nx !/ ( x ! (13)
~ ~
n 511 n n 511 n
calculation is dependent upon the average carbon number of
11.6 Selection of pattern and sensitivity data for matrix the types present. The average carbon number of the paraffins
carbon number of the types present. The average carbon and cycloparaffin types ((’s 71, 69, 123, and 149), are related
number of the paraffins and cycloparaffins ((71 and (67, to the calculated average carbon number of the alkylbenzenes
respectively)arerelatedtothecalculatedaveragecarbonofthe of the aromatic fraction (11.3), as shown in Table 2. The (91
alkylbenzenes (11.3), as shown in Table 2. Both (71 and (67 is included in the saturate fraction as a check on the efficiency
are included in the aromatic fraction matrix to check on oftheseparationprocedure.Thepatternandsensitivitydatafor
possible overlap in the separation. The other types present, the (91 are based on the calculated or estimated average
represented by (’s 103, 115, 153, and 151, are usually carbon number from the mass spectra of the aromatic fraction
relatively low in concentration so that their parent ions are (see11.3).Fromthedeterminedaveragecarbonnumbersofthe
affectedbyothertypespresent.Thecalculationoftheiraverage hydrocarbon types, a matrix for the saturate fraction is set up
carbonnumberisnotstraightforward.Therefore,theiraverage usingthecalibrationdatagiveninTable3.Asamplematrixfor
carbon numbers are estimated by inspection of the aromatic the saturate fraction is shown in Table 5. The matrix calcula-
spectrum. Generally, their average carbon numbers may be tions of the saturate fraction consists in solving a set of
D2425–99
TABLE 3 Patterns and Sensitivities for Middle Distillates
Hydrocarbon
Paraffins Noncondensed Cycloparaffins Condensed Dicycloparaffins Condensed Tricycloparaffins
Type
Carbon No. 12 13 14.5 15.5 12 13 14.5 15.5 13 14.5 15.5 13 14.5 15.5
Peaks read:
(71 100 100 100 100 44 6 6 2 1.1 1.5 1
...
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