ASTM D7798-20

Standard Test Method for Boiling Range Distribution of Petroleum Distillates with Final Boiling Points up to 538 °C by Ultra Fast Gas Chromatography (UF GC)

SIGNIFICANCE AND USE
5.1 The boiling range distribution of petroleum distillate fractions provides an insight into the composition of feed stocks and products related to petroleum refining processes. A major advantage of the fast analysis time obtained by this test method is increasing product through put and reduced lab testing time by a minimum factor of 3. This gas chromatographic determination of boiling range may be used to replace conventional distillation methods for control of refining operations and for product specification testing with the mutual agreement of interested parties.  
5.2 Boiling range distributions obtained by this test method are essentially equivalent to those obtained by true boiling point (TBP) distillation (see Test Method D2892). They are not equivalent to results from low efficiency distillations such as those obtained with Test Method D86 or D1160.
SCOPE
1.1 This test method covers the determination of the boiling range distribution of petroleum products and biodiesel formulations, B5, B10, and B20. It is applicable to petroleum distillates having a final boiling point not greater than 538 °C or lower at atmospheric pressure as measured by this test method. The difference between the initial boiling point and the final boiling point shall be greater than 55 °C.  
1.2 The test method is not applicable for analysis of petroleum distillates containing low molecular weight components (for example naphthas, reformates, gasolines, full range crude oils). Materials containing heterogeneous mixtures (for example, alcohols, ethers, acids or esters, except biodiesels) or residue are not to be analyzed by this test method. See Test Methods D3710, D7096, D6352, or D7169.  
1.3 This test method uses the principles of simulated distillation methodology. This test method uses gas chromatographic components that allow the entire analysis from sample to sample to occur in 5 min or less. In these instruments the column is heated directly at rates 10 to 15 times that of a conventional gas chromatograph and thus the analysis time is reduced from sample to sample.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4.1 Exception—Appendix X1 includes temperatures in Fahrenheit for information only.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2020
• ICS: 75.080 - Petroleum products in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0H - Chromatographic Distribution Methods

Relations

• Refers: ASTM D6708-24 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Mar-2024
• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D86-23ae1 - Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
• Effective Date: 01-Dec-2023
• Refers: ASTM D86-23a - Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
• Effective Date: 01-Dec-2023
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D2892-23 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-Nov-2023
• Refers: ASTM D4626-23 - Standard Practice for Calculation of Gas Chromatographic Response Factors
• Effective Date: 01-Oct-2023
• Refers: ASTM D2887-23 - Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
• Effective Date: 01-Jul-2023
• Refers: ASTM D2892-20 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-Jun-2020
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM D4626-95(2019) - Standard Practice for Calculation of Gas Chromatographic Response Factors
• Effective Date: 01-Dec-2019
• Refers: ASTM D6352-19e1 - Standard Test Method for Boiling Range Distribution of Petroleum Distillates in Boiling Range from 174 °C to 700 °C by Gas Chromatography
• Effective Date: 01-Dec-2019
• Refers: ASTM D6352-19 - Standard Test Method for Boiling Range Distribution of Petroleum Distillates in Boiling Range from 174 °C to 700 °C by Gas Chromatography
• Effective Date: 01-Dec-2019
• Refers: ASTM E594-96(2019) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM D2887-19 - Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
• Effective Date: 01-Jul-2019

Overview

ASTM D7798-20 is the internationally recognized standard test method for determining the boiling range distribution of petroleum distillates and select biodiesel blends using Ultra Fast Gas Chromatography (UF GC). Developed by ASTM International, this standard enables rapid, reliable simulation of distillation curves for petroleum products with final boiling points up to 538 °C, significantly reducing laboratory testing times compared to traditional methods.

This test method is essential for petroleum refiners, quality control labs, and fuel product analysts who require accurate and efficient boiling range data to inform refining operations, product specifications, and process optimization. By simulating the distillation process using high-speed gas chromatographic techniques, ASTM D7798-20 offers repeatable and precise boiling range results, equivalent to those obtained by true boiling point (TBP) distillation.

Key Topics

• Ultra Fast Gas Chromatography (UF GC): Utilizes advanced chromatographic instrumentation to heat the column at rates 10-15 times faster than conventional systems, achieving complete analysis in five minutes or less.
• Applicability: Suitable for petroleum distillates and biodiesel blends (B5, B10, and B20) with a final boiling point ≤ 538 °C and a boiling range difference > 55 °C.
• Precision and Throughput: Reduces analysis time by a minimum factor of three, increasing sample throughput and supporting rapid decision-making in industrial processes.
• Simulated Distillation Principles: Mimics the separation order of hydrocarbons as in TBP distillation, providing a detailed boiling range distribution based on calibrated retention times.
• Limitations: Not intended for products with low molecular weight components (naphthas, reformates, gasolines, full range crude oils) or samples containing heterogeneous mixtures (other alcohols, ethers, acids, or esters except biodiesels), or residue.
• Detection and Data Quality: Employs a flame ionization detector (FID) and robust data handling, ensuring high sensitivity, accuracy, and reproducibility in measured results.

Applications

ASTM D7798-20 is widely used in the petroleum and fuels industry for:

• Refinery Process Control: Monitoring and controlling refining operations by providing rapid boiling range distribution data for feedstock and product streams.
• Product Specification Testing: Assisting in certifying final product quality where precise boiling range is required, supporting regulatory and commercial requirements.
• Biodiesel Blends Analysis: Evaluating the boiling characteristics of biodiesel formulations (B5, B10, B20), ensuring compliance with market or regulatory standards.
• Replacement for Conventional Distillation: Serving as an efficient alternative to ASTM D2892 TBP distillation, with comparable results for eligible sample types, thus reducing the need for labor-intensive distillation processes.
• Laboratory Productivity: Supporting high-throughput labs by enabling quicker turnaround on boiling range distribution analyses, freeing resources for other testing needs.

Related Standards

Understanding ASTM D7798-20 is enhanced by familiarity with these related standards:

• ASTM D86 – Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
• ASTM D1160 – Distillation of Petroleum Products at Reduced Pressure
• ASTM D2887 – Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
• ASTM D2892 – Distillation of Crude Petroleum (15-Theoretical Plate Column) - reference for TBP distillation equivalence
• ASTM D6352, D7096, D7169 – Additional methods for boiling range distribution in various sample types
• ASTM E355, E594, E1510 – Practices for gas chromatography terms, detector usage, and column installation

Practical Value

ASTM D7798-20 provides a fast, accurate, and standardized approach for assessing boiling range distributions in petroleum and biodiesel products, supporting better process control, improved lab efficiency, and reliable quality assurance. Its adoption helps laboratories and refineries meet regulatory requirements, optimize throughput, and ensure product consistency in a global fuels market.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7798 − 20
Standard Test Method for
Boiling Range Distribution of Petroleum Distillates with
Final Boiling Points up to 538 °C by Ultra Fast Gas
Chromatography (UF GC)
This standard is issued under the fixed designation D7798; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 Thistestmethodcoversthedeterminationoftheboiling
ization established in the Decision on Principles for the
range distribution of petroleum products and biodiesel
Development of International Standards, Guides and Recom-
formulations, B5, B10, and B20. It is applicable to petroleum
mendations issued by the World Trade Organization Technical
distillates having a final boiling point not greater than 538°C
Barriers to Trade (TBT) Committee.
or lower at atmospheric pressure as measured by this test
method.Thedifferencebetweentheinitialboilingpointandthe
2. Referenced Documents
final boiling point shall be greater than 55°C.
2.1 ASTM Standards:
1.2 The test method is not applicable for analysis of
D86Test Method for Distillation of Petroleum Products and
petroleum distillates containing low molecular weight compo-
Liquid Fuels at Atmospheric Pressure
nents (for example naphthas, reformates, gasolines, full range
D1160TestMethodforDistillationofPetroleumProductsat
crude oils). Materials containing heterogeneous mixtures (for
Reduced Pressure
example, alcohols, ethers, acids or esters, except biodiesels) or
D2887Test Method for Boiling Range Distribution of Pe-
residue are not to be analyzed by this test method. See Test
troleum Fractions by Gas Chromatography
Methods D3710, D7096, D6352,or D7169.
D2892Test Method for Distillation of Crude Petroleum
1.3 This test method uses the principles of simulated distil-
(15-Theoretical Plate Column)
lation methodology. This test method uses gas chromato- D3710TestMethodforBoilingRangeDistributionofGaso-
graphic components that allow the entire analysis from sample line and Gasoline Fractions by Gas Chromatography
to sample to occur in 5min or less. In these instruments the (Withdrawn 2014)
column is heated directly at rates 10 to 15 times that of a D4626Practice for Calculation of Gas Chromatographic
conventional gas chromatograph and thus the analysis time is Response Factors
reduced from sample to sample. D6300Practice for Determination of Precision and Bias
Data for Use in Test Methods for Petroleum Products,
1.4 The values stated in SI units are to be regarded as
Liquid Fuels, and Lubricants
standard. No other units of measurement are included in this
D6352Test Method for Boiling Range Distribution of Pe-
standard.
troleum Distillates in Boiling Range from 174°C to
1.4.1 Exception—Appendix X1 includes temperatures in
700°C by Gas Chromatography
Fahrenheit for information only.
D6708Practice for StatisticalAssessment and Improvement
1.5 This standard does not purport to address all of the
of Expected Agreement Between Two Test Methods that
safety concerns, if any, associated with its use. It is the
Purport to Measure the Same Property of a Material
responsibility of the user of this standard to establish appro-
D7096Test Method for Determination of the Boiling Range
priate safety, health, and environmental practices and deter-
Distribution of Gasoline by Wide-Bore Capillary Gas
mine the applicability of regulatory limitations prior to use.
Chromatography
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Subcommittee D02.04.0H on Chromatographic Distribution Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2020. Published November 2020. Originally the ASTM website.
approved in 2013. Last previous edition approved in 2015 as D7798–15. DOI: The last approved version of this historical standard is referenced on
10.1520/D7798-20. www.astm.org.
*A Summary of Changes 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
D7798 − 20
D7169 Test Method for Boiling Point Distribution of 4. Summary of Test Method
Samples with Residues Such as Crude Oils and Atmo-
4.1 The boiling range distribution of hydrocarbon fractions
spheric and Vacuum Residues by High Temperature Gas
obtained by physical distillation is simulated by the use of gas
Chromatography
chromatography (GC). The GC column heating is accom-
E355PracticeforGasChromatographyTermsandRelation-
plished by supplying heat to the column directly instead of an
ships
oven with a consequence that the elution time is considerably
E594Practice for Testing Flame Ionization Detectors Used
shortened. Thus, cycle times of 5min or less (heating and
in Gas or Supercritical Fluid Chromatography
cooling) is achieved. A non-polar capillary gas chromato-
E1510Practice for Installing Fused Silica Open Tubular
graphic column is used to separate the hydrocarbon compo-
Capillary Columns in Gas Chromatographs
nents of the sample and cause them to elute in order of
increasing boiling point.
3. Terminology
4.2 Depending on the analyzer and column used, a sample
3.1 Definitions:
aliquot is diluted with a viscosity reducing solvent or intro-
3.1.1 This test method makes reference to many common
ducedneatintothechromatographicsystem.Samplevaporiza-
gas chromatographic procedures, terms, and relationships.
tion is provided by separate heating of the point of injection or
Detailed definitions of these can be found in Practices E355,
in conjunction with column oven heating.
E594, and E1510.
4.3 The column temperature is raised at a reproducible
3.1.2 area slice, n—in gas chromatography,thearea,result-
linear rate to effect separation of the hydrocarbon components
ing from the integration of the chromatographic detector
in order of increasing boiling point. The elution of sample
signal, within a specified retention time interval.
components is quantitatively determined using a flame ioniza-
3.1.3 corrected area slice, n—in gas chromatography,an
tion detector. The detector signal integral is recorded as area
area slice corrected for baseline offset, by subtraction of the
slices for consecutive retention time intervals during the
corresponding area slice in a previously recorded blank (non-
analysis.
sample) analysis.
4.4 Retentiontimesofknownnormalparaffinhydrocarbons,
3.1.4 cumulative corrected area, n—in gas
spanning the scope of the test method (C to C ), are
5 44
chromatography, the accumulated sum of corrected area slices
determined and correlated to their boiling point temperatures.
from the beginning of the analysis through to a given retention
(Refer to Table 1.) The normalized cumulative corrected
time, ignoring any non-sample areas (for example, solvent
sample areas for each consecutive recorded time interval are
peak area).
used to calculate the boiling range distribution. The boiling
3.1.5 Final Boiling Point (FBP), n—in gas
point temperature at each reported percent off increment is
chromatography, the temperature (corresponding to the reten-
calculated from the retention time calibration.
tion time) at which a cumulative corrected area count equal to
5. Significance and Use
99.5% of the total sample area under the chromatogram is
obtained.
5.1 The boiling range distribution of petroleum distillate
fractions provides an insight into the composition of feed
3.1.6 Initial Boiling Point (IBP), n—in gas
stocks and products related to petroleum refining processes.A
chromatography, the temperature (corresponding to the reten-
major advantage of the fast analysis time obtained by this test
tion time) at which a cumulative corrected area count equal to
method is increasing product through put and reduced lab
0.5% of the total sample area under the chromatogram is
testing time by a minimum factor of 3. This gas chromato-
obtained.
graphic determination of boiling range may be used to replace
3.1.7 slice rate, n—in gas chromatography,thetimeinterval
conventional distillation methods for control of refining opera-
used to integrate the continuous (analog) chromatographic
tions and for product specification testing with the mutual
detector response during an analysis, expressed in Hz.
agreement of interested parties.
3.1.7.1 Discussion—for example, integrations or slices per
5.2 Boiling range distributions obtained by this test method
second.
are essentially equivalent to those obtained by true boiling
3.1.8 slice time, n—in gas chromatography, the time dura-
point(TBP)distillation(seeTestMethodD2892).Theyarenot
tionoftheslice,inseconds.Theslicetimeisthetimeattheend
equivalent to results from low efficiency distillations such as
of each contiguous area slice.
those obtained with Test Method D86 or D1160.
3.1.9 total sample area, n—in gas chromatography, the
cumulative corrected area, from the initial area point to the
6. Apparatus
final area point.
6.1 Chromatograph—Thegaschromatographicsystemused
3.2 Abbreviations:
shall have the following performance characteristics:
3.2.1 Acommonabbreviationofhydrocarboncompoundsis 6.1.1 Column Heating Assembly—Capable of sustaining a
to designate the number of carbon atoms in the compound. A programmed temperature operation from 40°C up to 400°C.
prefix is used to indicate the carbon chain form, while a 6.1.2 Column Temperature Programmer—The column
subscripted suffix denotes the number of carbon atoms (for shouldbecapableoflinearprogrammedtemperatureoperation
example, n-C normal decane; iC = iso tetradecane). up to 400°C at selectable linear rates from a minimum of
l0 l4
D7798 − 20
A,B -12
TABLE 1 Boiling Points of n-Paraffins
6.1.3.3 Minimum Detectability1×10 g carbon per
Carbon Boiling Boiling
second for n-C .
Number Point, °C Point, °F
6.1.3.4 Linear Range >10 .
536 97
6.1.3.5 Connection of the column to the detector shall be
6 69 156
7 98 209
such that no temperature below the column inlet temperature
8 126 258
exists. Refer to E1510 for proper installation and conditioning
9 151 303
of the capillary column.
10 174 345
11 196 385
6.1.4 Sample Inlet System—Any sample inlet system ca-
12 216 421
pable of operating continuously at a temperature equivalent to
13 235 456
14 254 488 the maximum column temperature employed. Programmed
15 271 519
temperature vaporization (PTV) and programmable cool on-
16 287 548
column injection and split injection systems have been used
17 302 576
successfully. Table 2 gives some examples of operating con-
18 316 601
19 330 626
ditions of commercially available instrumentation. The inlet
20 344 651
should be capable to continuously deliver the sample compo-
21 356 674
nents in to the column by maintaining the temperature higher
22 369 695
23 380 716
than the column temperature.
24 391 736
6.1.5 Carrier Gas Flow Control—The chromatograph shall
25 402 755
26 412 774
beequippedwithcarriergaspressureorflowcontrolcapableof
27 422 791
maintaining constant carrier gas flow control through the
28 431 808
column throughout the column temperature program cycle.
29 440 825
30 449 840
The flow shall not vary by more than 1% from the initial
31 458 856
temperature to the end column temperature.
32 466 870
33 474 885
6.2 Microsyringe—Syringes of 0.1µL to 5µL capacity are
34 481 898
suitable for this test method. Consult manufacturer for specific
35 489 912
36 496 925 details on requirements for syringes compatible with autosam-
37 503 937
pler and injection technique used.
38 509 948
6.2.1 Automaticsyringeinjectionisrequiredtoachievebest
39 516 961
40 522 972
precision.
41 528 982
42 534 993
6.3 Column—This test method is limited to the use of
43 540 1004
non-polar wall coated open tubular (WCOT) columns of high
44 545 1013
thermalstability.Fusedsilica,andstainlesssteelcolumns,with
A
API Project 44, October 31, 1972 is believed to have provided the original normal
a 0.32mm to 0.18mm inside diameter have been successfully
paraffin boiling point data that are listed in Table 1. However, over the years some
of the data contained in both API Project 44 (Thermodynamics Research Center used. Cross-linked or bonded 100% dimethyl-polysiloxane
Hydrocarbon Project) and Test Method D2887 have changed, and they are no
stationary phases with film thickness of 0.1µm to 1.0 µm have
longer equivalent. Table 1 represents the current normal paraffin boiling point
been used. It is required that the choice of these two variables
values accepted by Subcommittee D02.04 and found in all test methods under the
jurisdiction of Section D02.04.0H. (columni.d.andphasethickness)allowtheelutionofC toC
5 44
B
Test Method D2887 has traditionally used n-paraffin boiling points rounded to the
duringthetemperatureprogrammingphaseofthecolumn.The
nearest whole degree for calibration. The boiling points listed in Table 1 are correct
column and conditions shall provide separation of typical
to the nearest whole number in both degrees Celsius and degrees Fahrenheit.
However, if a conversion is made from one unit to the other and then rounded to
petroleum hydrocarbons in order of increasing boiling point
a whole number, the result will not agree with the table value for a few carbon
and meet the column resolution requirements of 8.2.1. The
numbers. For example, the boiling point of n-heptane is 98.425 °C, which is
column shall provide a resolution of at least three (3) using the
correctly rounded to 98 °C in the table. However, converting 98.425 °C gives
209.165 °F, which rounds to 209 °F, while converting 98 °C gives 208.4 °F, which
testmethodoperatingconditions.Table2givessomeexamples
rounds to 208 °F. Carbon numbers 2, 4, 7, 8, 9, 13, 14, 15, 16, 25, 27, and 32 are
of columns used successfully.
affected by rounding.
6.4 Data Acquisition System:
6.4.1 Computer—Means shall be provided for determining
60°C⁄min up to 350°C⁄min. The programming rate shall be the accumulated area under the chromatogram. This can be
sufficientlyreproducibletoobtaintheretentiontimerepeatabil- done by means of a computer based chromatography data
ity for the mixture described in 7.6. system. The computer system shall have normal chromato-
6.1.3 Detector—This test method requires a flame ioniza- graphic software for measuring the retention time and areas of
tion detector (FID). The detector shall meet or exceed the eluting peaks (peak detection mode). In addition, the system
following specifications as detailed in Practice E594. The shall be capable of converting the continuously integrated
flame jet should have an orifice of approximately 0.018in. or detector signal into area slices of fixed duration (area slice
0.45mm or as specified by the manufacturer. mode). These contiguous area slices, collected for the entire
6.1.3.1 Operating Temperature approximately 380°C to analysis, are stored for later processing. Gas Chromatographs
400°C. withanalogtodigitalconversionofthedetectorsignal,shallbe
6.1.3.2 Sensitivity >0.005 coulombs/g carbon. operated within the linear range of the detector/electrometer
D7798 − 20
TABLE 2 Examples of UFGC Operating Conditions and Column Assembly Heating Types
Instrument A Instrument B Instrument C
Parameters
Resistively heated columns Resistively heated columns Resistively heated columns
Inlet Temperature Programmable TPI; 100 °C to 360 °C Split: Split ratio 50:1- 150:1 350 °C Split/Splitless 0.4 min purge delay
@ 300 °C ⁄min-1.0 min
Auto sampler required required required
Data collection 100 Hz 100 Hz 100 Hz
Column 4 m-0.25 mm-0.25 µ pdms 2 m-0.32 mm-0.20 µ pdms 5 m-0.53 mm-2.65 µ pdms
Inlet/FID Transfer Lines 360 °C 350 °C 340 °C
Flow conditions 4 mL/min 1 mL/min 9 mL/min
Make-up gas 25 mL/min 25 mL/min
Detector Flame Ionization 400 °C Flame Ionization 350 °C Flame Ionization 380 °C
Column program 40 °C to 360 °C at 160 °C ⁄min-1min 40 °C to 375 °C at 60 °C ⁄min 40 °C (0.5 min) to 240 °C at
100 °C ⁄min
then 340 °C at 100 °C ⁄min-0.5 min
Equilibration time 2 min 1.5 min 2 min
Sample size 0.2 µL 0.3 µL to 0.08 µL 0.2 µL
Sample dilution 2 % in CS 2% in CS up to neat neat
2 2
Calibration dilution 1 % total solids in CS 0.1 % by weight each component 1 % total solids in CS
2 2
in CS
Carrier He H He
system used. Since the chromatogram is developing in a very response and reduced peak skewness. It is miscible with
shorttimeandsincethepeakseluteatafastrate,itisnecessary hydrocarbonsandprovidesarelativelysmallresponsewiththe
to acquire the signals at 50Hz to 100Hz. FID. The quality (hydrocarbon content) should be determined
by this test method prior to use as a sample diluent.
7. Reagents and Materials
(Warning—Carbon disulfide is extremely flammable and
toxic.)
7.1 Carrier Gas—Helium, or hydrogen of high purity
(99.999%) have been used as shown in Table 2.(Warning—
7.5 Cyclohexane (C H )—(99+% pure) may be used as a
6 12
Helium and Hydrogen are compressed gases under high
viscosity reducing solvent. It is miscible with hydrocarbons;
pressure.) (Warning—Hydrogen is an extremely flammable
however, it has a high response to the FID. Use Cyclohexane
gas.) Additional purification is recommended by the use of
for the retention time solvent only The quality (hydrocarbon
molecular sieves or other suitable agents to remove water,
content) should be determined by this test method prior to use
oxygen, and hydrocarbons. Available pressure shall be suffi-
as a sample diluent. (Warning—Cyclohexane is flammable.)
cient to ensure a constant carrier gas flow rate.
7.6 Calibration Mixture—A qualitative mixture of
7.2 Hydrogen—Hydrogen of high purity (99.999%) is used
n-paraffins (nominally C to C ) dissolved in a suitable
5 44
as fuel for the flame ionization detector (FID). (Warning—
solvent. The concentration is adjusted for the injection tech-
Hydrogen is an extremely flammable gas.)
nique used (for example, direct injection, PTV split etc). For
7.3 Air—High purity (for example hydrocarbon free) com- direct injections approximately one part of n-paraffin mixture
pressed air is used as the oxidant for the flame ionization
to one hundred parts of solvent may be satisfactory. At least
detector(FID).(Warning—Compressedairisagasunderhigh one compound in the mixture shall have a boiling point lower
pressure and supports combustion.)
than the initial boiling point of the sample being analyzed, as
defined in the scope of this test method (1.1). Calibration
7.4 Solvents—Unless otherwise indicated, it is intended that
mixtures containing normal paraffins with the carbon numbers
all solvents conform to the specifications of the committee on
5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 20, 24, 28, 32, 36,
Analytical Reagents of theAmerican Chemical Society where
40, and 44 have been found to provide a sufficient number of
such specifications are available. Other grades may be used
points to generate a reliable calibration curve.
provided it is first ascertained that the solvent is of sufficiently
high purity to permit its use without lessening the accuracy of
7.7 Response Linearity Mixture—If the calibration mixture
the determination. The polar solvent used to dissolve the
is prepared quantitatively it may be used to determine the
sample shall not interfere with any of the peaks of the sample
linearity of the detector. Alternatively, response and injection
components.
discrimination over the boiling range of interest may be tested
7.4.1 Carbon Disulfide (CS )—(99+%pure)maybeusedas
with a mixture of at least two petroleum oils which yield a
a viscosity reducing solvent and as a means of reducing mass
baselinegapbetweenthetwotoallowrelativedeterminationof
of sample introduced onto the column to ensure linear detector
concentration. The two fractions that constitute the blend
should contain no aromatic components.
7.8 Reference Material—The Reference Gas Oil (RGO)
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
whose values are listed in D2887 is used in this test method.
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Depending on the analyzer and the columns used, either a neat
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
sample or a solution in CS is used. Solutions of the RGO are
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma- 2
copeial Convention, Inc. (USPC), Rockville, MD. made and chromatographed and it is a requirement that the
D7798 − 20
referenceBoilingPointvaluesbeobtained(seeD2887Table3) 8.2 System Performance Specification:
in order to proceed with sample analysis.
8.2.1 Column Resolution—The column resolution, influ-
enced by both the column physical parameters and operating
8. Preparation of Apparatus
conditions, affects the overall determination of boiling range
8.1 Gas Chromatograph Setup:
distribution. Resolution is therefore specified to maintain
8.1.1 Place the gas chromatograph and ancillary equipment
equivalence between different systems (laboratories) employ-
into operation in accordance with the manufacturer’s instruc-
ing this test method. Resolution is determined using Eq 1 and
tions. Recommended operating conditions for several ap-
the C and C n-paraffins from a calibration mixture analysis
16 18
proaches used for ultra fast gas chromatographs are shown in
(see 7.6). Resolution (R) should be at least three (3) using the
Table 2.
identical conditions employed for sample analyses. An ex-
8.1.2 When attaching the column to the detector inlet,
ampleillustratingtheuseofthiscalculationisshowninFig.4.
ensure that the end of the column terminates as close as
R 52~t 2 t !⁄~1.699 ~w 1 w !! (1)
possible to the FID jet. Follow the instructions in E1510 or as
2 1 2 1
specified by the manufacturer.
where:
8.1.3 The FID should be periodically inspected and, if
R = resolution,
necessary, remove any foreign deposits formed in the detector
t = time (s) for the n-C peak maximum,
1 16
from combustion of silicone liquid phase or other materials.
t = time (s) for the n-C peak maximum,
2 18
Such deposits will change the response characteristics of the
w = peak width (s), at half height, of the n-C peak, and
1 16
detector.
w = peak width (s), at half height, of the n-C peak.
2 18
8.1.4 The inlet liner and initial portion of the column shall
be periodically inspected and replaced if necessary to remove 8.2.2 Detector Response Calibration—This test method as-
extraneous deposits or sample residue. sumes that the FID response to petroleum hydrocarbons is
8.1.5 Column Conditioning—A new column will require
proportional to the mass of individual components. This shall
conditioning at the upper test method operating temperature to
beverifiedwhenthesystemisputinservice,andwheneverany
reduce or eliminate significant liquid phase bleed, resulting in
changes are made to the system or operational parameters.
a stable chromatographic baseline. Follow the guidelines
Analyzetheresponselinearitymixture(7.7)usingtheidentical
outlined in E1510 or as suggested by manufacturer. Columns
procedure to be used for the analysis of samples (Section 9).
may also be conditioned by repeated blank cycles until the
Calculate the relative response factor for each n-paraffin
baselineasstabilizedandqualitycontrolreferencesamplesare
(relative to n-eicosane, C ) as per Practice D4626 and Eq 2:
within specifications.
FIG. 1 Calibration Chromatogram Obtained at 200 °C ⁄Min
D7798 − 20
FIG. 2 Example Boiling Point Calibration Plot Obtained from an Ultra Fast Gas Chromatogram
FIG. 3 Designation of Parameters for Calculation of Peak Skewness Obtained from an Ultra Fast Chromatogram
F 5 ~M ⁄ A ! ⁄ ~M ⁄ A ! (2) The relative response factor (F ) of each n-paraffin shall not
n n n 20 20 n
deviate from unity by more than 65%.
where:
8.2.3 Column Temperature—The column temperature pro-
F = relative response factor,
n
gram profile is selected such that at least the C peak can be
M = mass of the n-paraffin in the mixture,
n
differentiated from the solvent and that the maximum boiling
A = peak area of the n-paraffin in the mixture,
n
M = mass of the n-eicosane in the mixture, and point (545°C) n-paraffin (C ) is eluted from the column
A = peak area of the n-eicosane in the mixture.
before end of the run time. The actual program rate used will
D7798 − 20
FIG. 4 Example for the Resolution Calculation for an Ultra Fast GC Calibration
be influenced by other operating variables such as column that temperature for the selected time. Following the analysis
dimensions, liquid phase film thickness, carrier gas and flow sequence protocol, cool the column to the initial starting
rate, and sample size. temperature.
8.2.4 Column Elution Characteristics—The column liquid
9.1.2 During the cool down and equilibration time, ready
phase is the non-polar phase 100% dimethyl-polysiloxane.
the computer system. If a retention time calibration is being
performed, use the peak detection mode. For samples and base
9. Procedure
line compensation (with or without solvent injection), use the
areaslicemodeoperation.Therecommendedslicerateforthis
9.1 Analysis Sequence Protocol—Defineanduseapredeter-
test method is 100.0 Hz. See Annex A1 for selection of the
mined schedule of analysis events designed to achieve maxi-
acquisition rate.
mum reproducibility for these determinations. The schedule
will include cooling the column oven and injector to the initial 9.1.3 At the exact time set by the schedule, inject either the
starting temperature, equilibration time, sample injection and calibrationmixture,solvent,orsampleintothechromatograph;
system start, analysis, and final temperature hold time. or make no injection (baseline blank).At the time of injection,
9.1.1 After chromatographic conditions have been set to startthechromatographtimecycleandtheintegrator/computer
meet performance requirements, program the column tempera- data acquisition. Follow the analysis protocol for all subse-
ture upward to the maximum temperature to be used and hold quent repetitive analyses or calibrations.
D7798 − 20
9.2 Baseline Blank—Perform a blank analysis (baseline 9.3.2 Prepare a calibration table based upon the results of
blank)atleastonceperday.Theblankanalysismaybewithout the analysis of the calibration mixture by recording the time of
each peak maximum and the boiling point temperature in
injection or by injection of an equivalent solvent volume as
used with sample injections, depending upon the subsequent degrees Celsius (or Fahrenheit) for every component in the
mixture. The n-paraffin boiling point temperatures (atmo-
data handling capabilities for baseline/solvent compensation.
spheric equivalent temperatures) are listed in Table 1.An
The blank analysis is typically performed prior to sample
exampleofatypicalcalibrationgraph,showingretentiontimes
analyses, but may be useful if determined between samples or
vs. boiling points for each n-paraffin, is found in Fig. 2.
at the end of a sample sequence to provide additional data
Calibration report is shown in Table 3.
regarding instrument operation or residual sample carry over
from previous sample analyses.
9.4 Sample Preparation—Sample aliquots are introduced
into the gas chromatograph as solutions in a suitable solvent
NOTE 1—If automatic baseline correction is provided by the gas
(for example carbon disulfide) or neat depending on the
chromatograph, further correction of area slices may not be required.
columns and GC being used.
However, if an electronic offset is added to the signal after baseline
compensation,additionalareaslicecorrectionmayberequiredintheform
9.4.1 Dilute the sample to approximately 2% by mass with
of offset subtraction. Consult the specific instrumentation instructions to
the solvent or as appropriate to ensure that the column is not
determine if an offset is applied to the signal. If the algorithm used is
overloaded. Table 2 gives some examples of dilutions and
unclear the slice area data can be examined to determine i
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7798 − 15 D7798 − 20
Standard Test Method for
Boiling Range Distribution of Petroleum Distillates with
Final Boiling Points up to 538 °C by Ultra Fast Gas
Chromatography (UF GC)
This standard is issued under the fixed designation D7798; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of the boiling range distribution of petroleum products and biodiesel formulations,
B5, B10, and B20. It is applicable to petroleum distillates having a final boiling point not greater than 538 °C or lower at
atmospheric pressure as measured by this test method. The difference between the initial boiling point and the final boiling point
shall be greater than 55 °C.
1.2 The test method is not applicable for analysis of petroleum distillates containing low molecular weight components (for
example naphthas, reformates, gasolines, full range crude oils). Materials containing heterogeneous mixtures (for example,
alcohols, ethers, acids or esters, except biodiesels) or residue are not to be analyzed by this test method. See Test Methods D3710,
D7096, D6352, or D7169.
1.3 This test method uses the principles of simulated distillation methodology. This test method uses gas chromatographic
components that allow the entire analysis from sample to sample to occur in 5 min or less. In these instruments the column is
heated directly at rates 10 to 15 times that of a conventional gas chromatograph and thus the analysis time is reduced from sample
to sample.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4.1 Exception—Appendix X1 includes temperatures in Fahrenheit for information only.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.04.0H on Chromatographic Distribution Methods.
Current edition approved Oct. 1, 2015Oct. 1, 2020. Published November 2015November 2020. Originally approved in 2013. Last previous edition approved in 20132015
as D7798 – 13.D7798 – 15. DOI: 10.1520/D7798-15.10.1520/D7798-20.
*A Summary of Changes 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
D7798 − 20
2. Referenced Documents
2.1 ASTM Standards:
D86 Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
D1160 Test Method for Distillation of Petroleum Products at Reduced Pressure
D2887 Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
D2892 Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
D3710 Test Method for Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography (Withdrawn
2014)
D4626 Practice for Calculation of Gas Chromatographic Response Factors
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D6352 Test Method for Boiling Range Distribution of Petroleum Distillates in Boiling Range from 174 °C to 700 °C by Gas
Chromatography
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
D7096 Test Method for Determination of the Boiling Range Distribution of Gasoline by Wide-Bore Capillary Gas
Chromatography
D7169 Test Method for Boiling Point Distribution of Samples with Residues Such as Crude Oils and Atmospheric and Vacuum
Residues by High Temperature Gas Chromatography
E355 Practice for Gas Chromatography Terms and Relationships
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs
3. Terminology
3.1 Definitions:
3.1.1 This test method makes reference to many common gas chromatographic procedures, terms, and relationships. Detailed
definitions of these can be found in Practices E355, E594, and E1510.
3.1.2 area slice, n—in gas chromatography, the area, resulting from the integration of the chromatographic detector signal, within
a specified retention time interval.
3.1.3 corrected area slice, n—in gas chromatography, an area slice corrected for baseline offset, by subtraction of the
corresponding area slice in a previously recorded blank (non-sample) analysis.
3.1.4 cumulative corrected area, n—in gas chromatography, the accumulated sum of corrected area slices from the beginning of
the analysis through to a given retention time, ignoring any non-sample areas (for example, solvent peak area).
3.1.5 Final Boiling Point (FBP), n—in gas chromatography, the temperature (corresponding to the retention time) at which a
cumulative corrected area count equal to 99.5 % of the total sample area under the chromatogram is obtained.
3.1.6 Initial Boiling Point (IBP), n—in gas chromatography, the temperature (corresponding to the retention time) at which a
cumulative corrected area count equal to 0.5 % of the total sample area under the chromatogram is obtained.
3.1.7 slice rate, n—in gas chromatography, the time interval used to integrate the continuous (analog) chromatographic detector
response during an analysis, expressed in Hz.
3.1.7.1 Discussion—
for example, integrations or slices per second.
3.1.8 slice time, n—in gas chromatography, the time duration of the slice, in seconds. The slice time is the time at the end of each
contiguous area slice.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
D7798 − 20
3.1.9 total sample area, n—in gas chromatography, the cumulative corrected area, from the initial area point to the final area point.
3.2 Abbreviations:
3.2.1 A common abbreviation of hydrocarbon compounds is to designate the number of carbon atoms in the compound. A prefix
is used to indicate the carbon chain form, while a subscripted suffix denotes the number of carbon atoms (for example, n-C normal
l0
decane; iC = iso tetradecane).
l4
4. Summary of Test Method
4.1 The boiling range distribution of hydrocarbon fractions obtained by physical distillation is simulated by the use of gas
chromatography (GC). The GC column heating is accomplished by supplying heat to the column directly instead of an oven with
a consequence that the elution time is considerably shortened. Thus, cycle times of 5 min or less (heating and cooling) is achieved.
A non-polar capillary gas chromatographic column is used to separate the hydrocarbon components of the sample and cause them
to elute in order of increasing boiling point.
4.2 Depending on the analyzer and column used, a sample aliquot is diluted with a viscosity reducing solvent or introduced neat
into the chromatographic system. Sample vaporization is provided by separate heating of the point of injection or in conjunction
with column oven heating.
4.3 The column temperature is raised at a reproducible linear rate to effect separation of the hydrocarbon components in order of
increasing boiling point. The elution of sample components is quantitatively determined using a flame ionization detector. The
detector signal integral is recorded as area slices for consecutive retention time intervals during the analysis.
4.4 Retention times of known normal paraffin hydrocarbons, spanning the scope of the test method (C to C ), are determined
5 44
and correlated to their boiling point temperatures. (Refer to Table 1.) The normalized cumulative corrected sample areas for each
consecutive recorded time interval are used to calculate the boiling range distribution. The boiling point temperature at each
reported percent off increment is calculated from the retention time calibration.
5. Significance and Use
5.1 The boiling range distribution of petroleum distillate fractions provides an insight into the composition of feed stocks and
products related to petroleum refining processes. A major advantage of the fast analysis time obtained by this test method is
increasing product through put and reduced lab testing time by a minimum factor of 3. This gas chromatographic determination
of boiling range may be used to replace conventional distillation methods for control of refining operations and for product
specification testing with the mutual agreement of interested parties.
5.2 Boiling range distributions obtained by this test method are essentially equivalent to those obtained by true boiling point (TBP)
distillation (see Test Method D2892). They are not equivalent to results from low efficiency distillations such as those obtained
with Test Method D86 or D1160.
6. Apparatus
6.1 Chromatograph—The gas chromatographic system used shall have the following performance characteristics:
6.1.1 Column Heating Assembly—Capable of sustaining a programmed temperature operation from 40 °C up to 400 °C.
6.1.2 Column Temperature Programmer—The column should be capable of linear programmed temperature operation up to
400 °C at selectable linear rates from a minimum of 60 °C ⁄min up to 350 °C ⁄min. The programming rate shall be sufficiently
reproducible to obtain the retention time repeatability for the mixture described in 7.6.
6.1.3 Detector—This test method requires a flame ionization detector (FID). The detector shall meet or exceed the following
specifications as detailed in Practice E594. The flame jet should have an orifice of approximately 0.018 in. or 0.45 mm or as
specified by the manufacturer.
6.1.3.1 Operating Temperature approximately 380 °C to 400 °C.
D7798 − 20
A,B
TABLE 1 Boiling Points of n-Paraffins
Carbon Boiling Boiling
Number Point, °C Point, °F
5 36 97
6 69 156
7 98 209
8 126 258
9 151 303
10 174 345
11 196 385
12 216 421
13 235 456
14 254 488
15 271 519
16 287 548
17 302 576
18 316 601
19 330 626
20 344 651
21 356 674
22 369 695
23 380 716
24 391 736
25 402 755
26 412 774
27 422 791
28 431 808
29 440 825
30 449 840
31 458 856
32 466 870
33 474 885
34 481 898
35 489 912
36 496 925
37 503 937
38 509 948
39 516 961
40 522 972
41 528 982
42 534 993
43 540 1004
44 545 1013
A
API Project 44, October 31, 1972 is believed to have provided the original normal
paraffin boiling point data that are listed in Table 1. However, over the years some
of the data contained in both API Project 44 (Thermodynamics Research Center
Hydrocarbon Project) and Test Method D2887 have changed, and they are no
longer equivalent. Table 1 represents the current normal paraffin boiling point
values accepted by Subcommittee D02.04 and found in all test methods under the
jurisdiction of Section D02.04.0H.
B
Test Method D2887 has traditionally used n-paraffin boiling points rounded to the
nearest whole degree for calibration. The boiling points listed in Table 1 are correct
to the nearest whole number in both degrees Celsius and degrees Fahrenheit.
However, if a conversion is made from one unit to the other and then rounded to
a whole number, the result will not agree with the table value for a few carbon
numbers. For example, the boiling point of n-heptane is 98.425 °C, which is
correctly rounded to 98 °C in the table. However, converting 98.425 °C gives
209.165 °F, which rounds to 209 °F, while converting 98 °C gives 208.4 °F, which
rounds to 208 °F. Carbon numbers 2, 4, 7, 8, 9, 13, 14, 15, 16, 25, 27, and 32 are
affected by rounding.
6.1.3.2 Sensitivity >0.005 coulombs/ g coulombs/g carbon.
-12
6.1.3.3 Minimum Detectability 1 × 10 g carbon per second for n-C .
6.1.3.4 Linear Range >10 .
6.1.3.5 Connection of the column to the detector shall be such that no temperature below the column inlet temperature exists.
Refer to E1510 for proper installation and conditioning of the capillary column.
6.1.4 Sample Inlet System—Any sample inlet system capable of operating continuously at a temperature equivalent to the
D7798 − 20
maximum column temperature employed. Programmed temperature vaporization (PTV) and programmable cool on-column
injection and split injection systems have been used successfully. Table 2 gives some examples of operating conditions of
commercially available instrumentation. The inlet should be capable to continuously deliver the sample components in to the
column by maintaining the temperature higher than the column temperature.
6.1.5 Carrier Gas Flow Control—The chromatograph shall be equipped with carrier gas pressure or flow control capable of
maintaining constant carrier gas flow control through the column throughout the column temperature program cycle. The flow shall
not vary by more than 1 % from the initial temperature to the end column temperature.
6.2 Microsyringe—Syringes of 0.1 μL to 5 μL capacity are suitable for this test method. Consult manufacturer for specific details
on requirements for syringes compatible with autosampler and injection technique used.
6.2.1 Automatic syringe injection is required to achieve best precision.
6.3 Column—This test method is limited to the use of non-polar wall coated open tubular (WCOT) columns of high thermal
stability. Fused silica, and stainless steel columns, with a 0.32 mm to 0.18 mm inside diameter have been successfully used.
Cross-linked or bonded 100 % dimethyl-polysiloxane stationary phases with film thickness of 0.1 μm to 1.0 μm have been used.
It is required that the choice of these two variables (column i.d. and phase thickness) allow the elution of C to C during the
5 44
temperature programming phase of the column. The column and conditions shall provide separation of typical petroleum
hydrocarbons in order of increasing boiling point and meet the column resolution requirements of 8.2.1. The column shall provide
a resolution of at least three (3) using the test method operating conditions. Table 2 gives some examples of columns used
successfully.
6.4 Data Acquisition System:
6.4.1 Computer—Means shall be provided for determining the accumulated area under the chromatogram. This can be done by
means of a computer based chromatography data system. The computer system shall have normal chromatographic software for
measuring the retention time and areas of eluting peaks (peak detection mode). In addition, the system shall be capable of
converting the continuously integrated detector signal into area slices of fixed duration (area slice mode). These contiguous area
slices, collected for the entire analysis, are stored for later processing. Gas Chromatographs with analog to digital conversion of
the detector signal, shall be operated within the linear range of the detector/electrometer system used. Since the chromatogram is
developing in a very short time and since the peaks elute at a fast rate, it is necessary to acquire the signals at 50 Hz to 100 Hz.
7. Reagents and Materials
7.1 Carrier Gas—Helium, or hydrogen of high purity (99.999 %) have been used as shown in Table 2. (Warning—Helium and
Hydrogen are compressed gases under high pressure.) (Warning—Hydrogen is an extremely flammable gas.) Additional
purification is recommended by the use of molecular sieves or other suitable agents to remove water, oxygen, and hydrocarbons.
Available pressure shall be sufficient to ensure a constant carrier gas flow rate.
TABLE 2 Examples of UFGC Operating Conditions and Column Assembly Heating Types
Instrument A Instrument B Instrument C
Parameters
Resistively heated columns Resistively heated columns Resistively heated columns
Inlet Temperature Programmable TPI; 100 °C to 360 °C Split: Split ratio 50:1- 150:1 350 °C Split/Splitless 0.4 min purge delay
@ 300 °C ⁄min-1.0 min
Auto sampler required required required
Data collection 100 Hz 100 Hz 100 Hz
Column 4 m-0.25 mm-0.25 μ pdms 2 m-0.32 mm-0.20 μ pdms 5 m-0.53 mm-2.65 μ pdms
Inlet/FID Transfer Lines 360 °C 350 °C 340 °C
Flow conditions 4 mL/min 1 mL/min 9 mL/min
Make-up gas 25 mL/min 25 mL/min
Detector Flame Ionization 400 °C Flame Ionization 350 °C Flame Ionization 380 °C
Column program 40 °C to 360 °C at 160 °C ⁄min-1min 40 °C to 375 °C at 60 °C ⁄min 40 °C (0.5 min) to 240 °C at
100 °C ⁄min
then 340 °C at 100 °C ⁄min-0.5 min
Equilibration time 2 min 1.5 min 2 min
Sample size 0.2 μL 0.3 μL to 0.08 μL 0.2 μL
Sample dilution 2 % in CS 2 % in CS up to neat neat
2 2
Calibration dilution 1 % total solids in CS 0.1 % by weight each component 1 % total solids in CS
2 2
in CS
Carrier He H He
D7798 − 20
7.2 Hydrogen—Hydrogen of high purity (99.999 %) is used as fuel for the flame ionization detector (FID). (Warning—Hydrogen
is an extremely flammable gas.)
7.3 Air—High purity (for example hydrocarbon free) compressed air is used as the oxidant for the flame ionization detector (FID).
(Warning—Compressed air is a gas under high pressure and supports combustion.)
7.4 Solvents—Unless otherwise indicated, it is intended that all solvents conform to the specifications of the committee on
Analytical Reagents of the American Chemical Society where such specifications are available. Other grades may be used
provided it is first ascertained that the solvent is of sufficiently high purity to permit its use without lessening the accuracy of the
determination. The polar solvent used to dissolve the sample shall not interfere with any of the peaks of the sample components.
7.4.1 Carbon Disulfide (CS )—(99+ % pure) may be used as a viscosity reducing solvent and as a means of reducing mass of
sample introduced onto the column to ensure linear detector response and reduced peak skewness. It is miscible with hydrocarbons
and provides a relatively small response with the FID. The quality (hydrocarbon content) should be determined by this test method
prior to use as a sample diluent. (Warning—Carbon disulfide is extremely flammable and toxic.)
7.5 Cyclohexane (C H )—(99+ % pure) may be used as a viscosity reducing solvent. It is miscible with hydrocarbons; however,
6 12
it has a high response to the FID. Use Cyclohexane for the retention time solvent only The quality (hydrocarbon content) should
be determined by this test method prior to use as a sample diluent. (Warning—Cyclohexane is flammable.)
7.6 Calibration Mixture—A qualitative mixture of n-paraffins (nominally C to C ) dissolved in a suitable solvent. The
5 44
concentration is adjusted for the injection technique used (for example, direct injection, PTV split etc). For direct injections
approximately one part of n-paraffin mixture to one hundred parts of solvent may be satisfactory. At least one compound in the
mixture shall have a boiling point lower than the initial boiling point of the sample being analyzed, as defined in the scope of this
test method (1.1). Calibration mixtures containing normal paraffins with the carbon numbers 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,
17, 18, 20, 24, 28, 32, 36, 40, and 44 have been found to provide a sufficient number of points to generate a reliable calibration
curve.
7.7 Response Linearity Mixture—If the calibration mixture is prepared quantitatively it may be used to determine the linearity of
the detector. Alternatively, response and injection discrimination over the boiling range of interest may be tested with a mixture
of at least two petroleum oils which yield a baseline gap between the two to allow relative determination of concentration. The
two fractions that constitute the blend should contain no aromatic components.
7.8 Reference Material—The Reference Gas Oil (RGO) whose values are listed in D2887 is used in this test method. Depending
on the analyzer and the columns used, either a neat sample or a solution in CS is used. Solutions of the RGO are made and
chromatographed and it is a requirement that the reference Boiling Point values be obtained (see D2887 TableX) Table 3) in order
to proceed with sample analysis.
8. Preparation of Apparatus
8.1 Gas Chromatograph Setup:
8.1.1 Place the gas chromatograph and ancillary equipment into operation in accordance with the manufacturer’s instructions.
Recommended operating conditions for several approaches used for ultra fast gas chromatographs are shown in Table 2.
8.1.2 When attaching the column to the detector inlet, ensure that the end of the column terminates as close as possible to the FID
jet. Follow the instructions in E1510 or as specified by the manufacturer.
8.1.3 The FID should be periodically inspected and, if necessary, remove any foreign deposits formed in the detector from
combustion of silicone liquid phase or other materials. Such deposits will change the response characteristics of the detector.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
D7798 − 20
8.1.4 The inlet liner and initial portion of the column shall be periodically inspected and replaced if necessary to remove
extraneous deposits or sample residue.
8.1.5 Column Conditioning—A new column will require conditioning at the upper test method operating temperature to reduce
or eliminate significant liquid phase bleed, resulting in a stable chromatographic baseline. Follow the guidelines outlined in E1510
or as suggested by manufacturer. Columns may also be conditioned by repeated blank cycles until the baseline as stabilized and
quality control reference samples are within specifications.
8.2 System Performance Specification:
8.2.1 Column Resolution—The column resolution, influenced by both the column physical parameters and operating conditions,
affects the overall determination of boiling range distribution. Resolution is therefore specified to maintain equivalence between
different systems (laboratories) employing this test method. Resolution is determined using Eq 1 and the C and C n-paraffins
16 18
from a calibration mixture analysis (see 7.6). Resolution (R) should be at least three (3) using the identical conditions employed
for sample analyses. An example illustrating the use of this calculation is shown in Fig. 4.
R 5 2~t 2 t !⁄~1.699 ~w 1 w !! (1)
2 1 2 1
where:
R = resolution,
t = time (s) for the n-C peak maximum,
1 16
t = time (s) for the n-C peak maximum,
2 18
w = peak width (s), at half height, of the n-C peak, and
1 16
w = peak width (s), at half height, of the n-C peak.
2 18
8.2.2 Detector Response Calibration—This test method assumes that the FID response to petroleum hydrocarbons is proportional
to the mass of individual components. This shall be verified when the system is put in service, and whenever any changes are made
to the system or operational parameters. Analyze the response linearity mixture (7.7) using the identical procedure to be used for
the analysis of samples (Section 9). Calculate the relative response factor for each n-paraffin (relative to n-eicosane, C ) as per
FIG. 1 Calibration Chromatogram Obtained at 200 °C ⁄Min
D7798 − 20
FIG. 2 Example Boiling Point Calibration Plot Obtained from an Ultra Fast Gas Chromatogram
FIG. 3 Designation of Parameters for Calculation of Peak Skewness Obtained from an Ultra Fast Chromatogram
Practice D4626 and Eq 2:
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FIG. 4 Example for the Resolution Calculation for an Ultra Fast GC Calibration
F 5 M ⁄ A ⁄ M ⁄ A (2)
~ ! ~ !
n n n 20 20
where:
F = relative response factor,
n
M = mass of the n-paraffin in the mixture,
n
A = peak area of the n-paraffin in the mixture,
n
M = mass of the n-eicosane in the mixture, and
A = peak area of the n-eicosane in the mixture.
The relative response factor (F ) of each n-paraffin shall not deviate from unity by more than 65 %.
n
8.2.3 Column Temperature—The column temperature program profile is selected such that at least the C peak can be
differentiated from the solvent and that the maximum boiling point (545 °C) n-paraffin (C ) is eluted from the column before end
of the run time. The actual program rate used will be influenced by other operating variables such as column dimensions, liquid
phase film thickness, carrier gas and flow rate, and sample size.
8.2.4 Column Elution Characteristics—The column liquid phase is the non-polar phase 100 % dimethyl-polysiloxane.
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9. Procedure
9.1 Analysis Sequence Protocol—Define and use a predetermined schedule of analysis events designed to achieve maximum
reproducibility for these determinations. The schedule will include cooling the column oven and injector to the initial starting
temperature, equilibration time, sample injection and system start, analysis, and final temperature hold time.
9.1.1 After chromatographic conditions have been set to meet performance requirements, program the column temperature upward
to the maximum temperature to be used and hold that temperature for the selected time. Following the analysis sequence protocol,
cool the column to the initial starting temperature.
9.1.2 During the cool down and equilibration time, ready the computer system. If a retention time calibration is being performed,
use the peak detection mode. For samples and base line compensation (with or without solvent injection), use the area slice mode
operation. The recommended slice rate for this test method is 100.0 Hz. See Annex A1 for selection of the acquisition rate.
9.1.3 At the exact time set by the schedule, inject either the calibration mixture, solvent, or sample into the chromatograph; or
make no injection (baseline blank). At the time of injection, start the chromatograph time cycle and the integrator/computer data
acquisition. Follow the analysis protocol for all subsequent repetitive analyses or calibrations.
9.2 Baseline Blank—Perform a blank analysis (baseline blank) at least once per day. The blank analysis may be without injection
or by injection of an equivalent solvent volume as used with sample injections, depending upon the subsequent data handling
capabilities for baseline/solvent compensation. The blank analysis is typically performed prior to sample analyses, but may be
useful if determined between samples or at the end of a sample sequence to provide additional data regarding instrument operation
or residual sample carry over from previous sample analyses.
NOTE 1—If automatic baseline correction is provided by the gas chromatograph, further correction of area slices may not be required. However, if an
electronic offset is added to the signal after baseline compensation, additional area slice correction may be required in the form of offset subtraction.
Consult the specific instrumentation instructions to determine if an offset is applied to the signal. If the algorithm used is unclear the slice area data can
be examined to determine if further correction is necessary. Determine if any offset has been added to the compensated signal by examining the corrected
area slices of those time slices which precede the elution of any chromatographic unretained substance. If these corrected area slices (representing the
true baseline) deviate from zero, subtract the average of these corrected area slices from each corrected area slice in the analysis. It is recommended that
the blank or solvent injection be made in the slice mode so as to offset slice by slice for sample and blank.
9.3 Retention Time vs. Boiling Point Calibration—A retention time vs. boiling point calibration should be performed weekly,
whenever maintenance is performed on the GC or as dictated by the GC performance. Inject an appropriate aliquot (0.2 μL to 1.0
μL) of the calibration mixture (7.6) into the chromatograph, using the analysis seq
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