SIST EN 18015:2024

SLOVENSKI STANDARD
01-september-2024
Goriva za motorna vozila - Določanje tipov ogljikovodikovih skupin in izbira
ogljikovodikov in kisikovih spojin - Metoda plinske kromatografije z vakuumsko
ultravijolično absorpcijsko spektroskopijo (GC-VUV)
Automotive fuels - Determination of hydrocarbon group types and select hydrocarbon
and oxygenate compounds - Gas chromatography with vacuum ultraviolet absorption
spectroscopy (GC-VUV) method
Kraftstoffe für Kraftfahrzeuge - Bestimmung von Kohlenwasserstoffgruppentypen und
Auswahl von Kohlenwasserstoff- und Sauerstoffverbindungen - Gaschromatographie mit
Vakuum-Ultraviolett-Absorptionsspektroskopie (GC-VUV)
Carburants pour automobiles - Détermination des types de groupes d’hydrocarbures et
sélection des composés d’hydrocarbures et d’oxygénation - Chromatographie gazeuse
avec spectroscopie d’absorption ultraviolette sous vide (GC-VUV) méthode
Ta slovenski standard je istoveten z: EN 18015:2024
ICS:
75.160.20 Tekoča goriva Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 18015
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2024
EUROPÄISCHE NORM
ICS 75.160.20
English Version
Automotive fuels - Determination of hydrocarbon group
types and select hydrocarbon and oxygenate compounds -
Gas chromatography with vacuum ultraviolet absorption
spectroscopy (GC-VUV) method
Carburants pour automobiles - Détermination de Kraftstoffe - Bestimmung von
groupes d'hydrocarbures et de sélections Kohlenwasserstoffgruppentypen und Auswahl von
d'hydrocarbures et de composés oxygénés - Kohlenwasserstoff- und Sauerstoffverbindungen -
Chromatographie en phase gazeuse avec une détection Gaschromatographie mit Vakuum-Ultraviolett-
par spectroscopie d'absorption ultraviolette sous vide Absorptionsspektroskopie (GC-VUV)
(GC-VUV)
This European Standard was approved by CEN on 17 June 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 18015:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 6
3 Terms, definitions and abbreviations . 6
3.1 Terms and definitions . 6
3.2 Abbreviations . 7
4 Principle . 7
5 Reagents and materials . 8
6 Apparatus . 10
7 Sampling . 11
8 Preparation of apparatus . 11
9 Calibration . 12
10 Pre-measurement validation . 13
11 Procedure . 14
12 Calculation . 16
13 Report . 21
14 Precision . 21
Annex A (normative) Generating absorbance spectra from intensity scan data . 23
A.1 Generating scan intensity data to VUV absorbance spectra . 23
A.2 Modelling absorbance data . 23
Annex B (informative) Relative response factors as function of molecular absorption cross
sections . 25
Bibliography . 27

European foreword
This document (EN 18015:2024) has been prepared by Technical Committee CEN/TC 19 “Gaseous and
liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”, the secretariat
of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2025, and conflicting national standards shall
be withdrawn at the latest by January 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
Introduction
This document is used for the determination of saturated (paraffinic, isoparaffinic and naphthenic),
olefinic, aromatic and oxygenated hydrocarbons in automotive motor gasoline according to European
fuel specifications such as EN 228 [1].
The test method described in this document is based on ASTM D8071 [2] with modifications to the gas
chromatographic oven temperature profile.
1 Scope
This test method is a standard procedure for the determination of saturates, olefins, aromatics and
oxygenates in unleaded petrol using gas chromatography and vacuum ultraviolet detection (GC-VUV).
Concentrations of compound classes and certain individual compounds are determined by mass fraction
% (m/m) or volume fraction % (V/V). The concentration ranges for which the method is applicable are
given in Table 1.
NOTE For the purposes of this document, the terms “% (m/m)” and “% (V/V)” are used to represent
respectively the mass fraction and the volume fraction, respectively.
This test method has been tested for unleaded petrol according EN 228 [1]; Although specifically
developed for the analysis of automotive motor gasoline including those that contain oxygenates this test
method applies to other hydrocarbon streams having similar boiling ranges, such as naphthas and
reformates.
The method is found to be applicable to petrol containing other oxygenates than indicated in Table 1,
such as isopropanol, iso-butanol, tert-butanol, n-propanol, acetone, tert-pentanol and di-isopropyl ether
(DIPE), however precision has not been determined.
Table 1 —Application ranges
Compound or group Units Concentration range
Saturates % (V/V) 21,48 to 80,87
Olefins % (V/V) 0,22 to 41,90
Aromatics % (V/V) 2,35 to 64,55
Benzene % (V/V) 0,20 to 2,54
Toluene % (V/V) 0,87 to 30,97
Ethylbenzene % (V/V) 0,20 to 3,45
Xylenes % (V/V) 0,49 to 18,59
Methanol % (V/V) 0,07 to 15,30
Ethanol % (V/V) 0,08 to 24,96
MTBE % (V/V) 0,22 to 22,21
ETBE % (V/V) 0,13 to 23,44
TAME % (V/V) 0,24 to 21,96
TAEE % (V/V) 0,24 to 8,60
Total oxygen content % (m/m) 0,52 to 12,19
Individual hydrocarbon components are typically not baseline-separated by the procedure described in
this test method. The coelutions are resolved at the detector using VUV absorbance spectra (Annex A)
and deconvolution algorithms.
While this test method reports by mass fraction % (m/m) or volume fraction % (V/V) for several specific
components that can be present in unleaded petrol, it does not attempt to speciate all possible
components that can occur in unleaded petrol. In particular, this test method is not intended as a type of
detailed hydrocarbon analysis (DHA).
WARNING — The use of this document can involve hazardous materials, operations and equipment. This
document does not purport to address all of the safety problems associated with its use. It is the
responsibility of the user of this document to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to use.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 3170, Petroleum liquids — Manual sampling (ISO 3170)
EN ISO 3171, Petroleum liquids — Automatic pipeline sampling (ISO 3171)
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1.1
response filter
mathematical operation performed on an absorbance spectrum for the purpose of converting the
spectrum to a single-valued response suitable for representation in a two-dimensional chromatogram
plot
3.1.2
library reference spectrum
absorbance spectrum representation of a molecular species stored in a library database and used for
identification of a compound/compound class or deconvolution of multiple coeluting compounds
3.1.3
response area
response summed over a given time interval having units of absorbance units
Note 1 to entry: Time factor necessary to convert a response area to a true mathematical area cancels out of all
critical calculations and is omitted.
3.1.4
relative response factor
RRF
function of the compound’s absorption cross section (expressed in cm per molecule) and methane’s
cross section
Note 1 to entry: The absorption cross section is averaged over the 125 nm to 240 nm wavelength region.
Note 2 to entry: A compound’s relative response factor is a function of the type and number of chemical bonds.
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
AU absorbance units
DHA detailed hydrocarbon analysis
GC gas chromatograph
GC-VUV gas chromatography with vacuum ultraviolet spectroscopy detection
RI retention index
RRF relative response factor
MTBE methyl tertiary butyl ether
ETBE ethyl tertiary butyl ether
TAME tertiary amyl methyl ether
TAEE tertiary amyl ethyl ether
DIPE diisopropyl ether
TID time interval deconvolution
iC4 isobutane
C4 butane
iC5 isopentane
C5 pentane
C15 pentadecane
VUV vacuum ultraviolet
4 Principle
A sample is introduced to a gas chromatographic (GC) system. After volatilization, the effluent is
introduced onto a GC column for separation, and then detected by a vacuum ultraviolet absorption
spectroscopy detector . The separation is accomplished using a 30 m, nonpolar phase capillary column
and a moderately fast temperature ramp (typical operating parameters of this test method are given in
Clause 11). Coelutions are resolved by the detector using vacuum ultraviolet (VUV) absorbance spectra
and deconvolution, more precisely, an automated time interval deconvolution (TID) algorithm.
The TID uses approximate retention indices, the VUV spectral library, and the concept of additive
absorption according to Beer−Lambert Law principles to bin pure or deconvolved mixture spectra into
class or species-specific responses in an automated fashion. The chromatogram is interrogated in defined
time intervals that can be adjusted depending on the complexity of the sample.
The response area for each sequential time interval over the entire chromatogram is determined. The
calculation of the results is based on the deconvoluted response areas of the saturates, olefins, aromatics
and oxygenates, in addition to several individual species components. The percent mass concentrations
are calculated from the response areas using class-based or compound-specific relative response factors
(RFFs). The volume percent concentrations are calculated from the mass concentrations by applying
specific component or class and carbon number-based density values. The mass and volume percent

VGA100, VGA101, VUV Analyze, VUV Vision are the trade name of products supplied by VUV Analytics, Cedar Park, Texas, USA 78613. This
information is given for the convenience of users of this document and does not constitute an endorsement by CEN of the product named.
calculations are software automated, whereby the RRFs and densities are a function of elution time in a
static database library.
5 Reagents and materials
5.1 Purity of reagents
Reagent grade chemicals shall be used in all tests. Use only reagents of recognized analytical grade. Other
grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit
its use without lessening the accuracy of the determination.
5.2 Helium carrier gas for gas chromatograph, 99,999 % pure.
NOTE Method performance has not been studied for other carrier gases such as hydrogen or nitrogen.
5.3 Purge or makeup gas, nitrogen, helium or argon, for vacuum ultraviolet detector, 99,999 % pure.
5.4 Methylene chloride or carbon disulfide, reagent grade, used as a solvent test sample and GC rinse
solvent. (Warning — Toxic material can be combustible at high temperatures.)
5.4.1 Alternate reagent grade solvents may be used provided that autosampler syringe carryover does
not interfere with sample analysis and that a suitable baseline (see 8.7) is achieved.
5.5 Retention time standard consisting of isobutane (iC4), butane (C4), isopentane (iC5), and pentane
(C5) through pentadecane (C15) linear alkanes, approximately 1 % by mass each, in suitable solvent such
as methylene chloride, used as retention time markers.
5.6 System validation mixture, having the components and approximate concentrations given in
Table 2. The actual concentration levels of the prepared system validation mixture in Table 2 are not
critical but shall be accurately known.
5.6.1 The components of the system validation mixture may be modified to include linear alkanes or
other compounds necessary for determining a retention index file (see 9.1 and 9.2).
5.6.2 The concentrations in Table 2 may be suitably modified to accommodate additional or
substituted components. The concentrations shall otherwise be accurately known.
Table 2 — System validation mixture
Component Concentration Component Concentration

% (m/m) % (m/m)
Cyclopentane 1,1 Benzene 2,2
n-Pentane 1,1 Toluene 2,2
Cyclohexane 2,1 trans-Decahydronaphthalene 4
2,3-Dimethylbutane 2,1 n-Tetradecane 4,5
n-Hexane 2,1 Ethylbenzene 4,5
1-Hexene 1,5 o-Xylene 4
Methylcyclohexane 4 n-Propylbenzene 5
Component Concentration Component Concentration
% (m/m) % (m/m)
4-Methyl-1-hexene 1,6 1,2,4-Trimethylbenzene 4,5
n-Heptane 3,5 1,2,3-Trimethylbenzene 5
1,2-Dimethylcyclohexane 5 1,2,4,5-Tetramethylbenzene 5
Isooctane 5 Pentamethylbenzene 5
n-Octane 5 Total Paraffins 32,2
1,2,4-Trimethylcyclohexane 4 Total Isoparaffins 7,1
n-Nonane 4,5 Total Olefins 3,1
n-Decane 4,5 Total Naphthenes 20,2
n-Undecane 3,5 Total Aromatics 37,4
n-Dodecane 3,5 Total Xylenes 4,0
5.7 Oxygenates mixture consisting of compounds in Table 3. The actual concentration levels of the
oxygenates mixture in Table 3 are not critical.
Table 3 — Oxygenate mixture
Component Concentration
% (V/V)
Methanol 0,5
Ethanol 5
MTBE 7
ETBE 7
TAME 7
TAEE 7
Isopropanol 1
Isobutanol 1
tert-Butanol 1
Propanol 1
Acetone 1
tert-Pentanol 1
DIPE 1
Toluene Balance
NOTE The oxygenates mixture is not a system validation mixture because tolerance limits for individual
compounds are not specified. The oxygenates mixture is run solely to set retention times of the target oxygenates
and the automated analytes to include retention time windows.
5.8 Reference sample, finished automotive motor gasoline(s) used as reference and which contains
components and concentration levels comparable to those of the test sample.
The composition of the reference solution should have been determined in an interlaboratory or
proficiency test or by other methods.
6 Apparatus
6.1 Gas chromatograph (GC), equipped with automated oven temperature control and split/splitless
inlet.
6.1.1 Flow controllers
The GC column flow systems shall be capable of constant flow or gas velocity throughout the temperature
ramp. The inlet pressure of the carrier gas supplied to the gas chromatograph shall be at least 485 kPa.
This will ensure that the minimum pressure needed to compensate for the increase in column back-
pressure as the column temperature is maintained.
6.1.2 Autosampler
It is highly recommended that the gas chromatograph is equipped with an autosampler. All statistical
data were obtained using a GC equipped with an autosampler.
6.1.3 Sub-ambient temperature control device
A cryogenic valve or other device is required to operate the GC oven at a sub-ambient temperature of at
least 5 °C.
6.2 Filters for oxygen, moisture or hydrocarbon types, to further purify GC carrier gas and detector
purge/makeup gas.
6.3 Capillary analytical column, nonpolar (for example, dimethyl polysiloxane) phase, dimensions
30 m length, 0,25 mm internal diameter, 0,25 µm film thickness.
6.4 Vacuum ultraviolet absorption spectroscopy detector, capable of measuring 125 nm to 240 nm
absorbance spectra with a wavelength resolution of 1 nm or better.
6.4.1 The detector shall be able to interface with a GC system and measure an eluent with a scan
frequency between 1 Hz and 10 Hz with a baseline peak-to-peak noise width over a 10  s interval not
greater than 0,002 AU when averaged over the following wavelength regions: 125 nm to 240 nm, 170 nm
to 200 nm, 125 nm to 160  nm, and 0,001 AU when averaged over the 140  nm to 160  nm wavelength
region.
NOTE The typical scan frequency is fixed at 4,5Hz (see Table 6).
6.4.2 The detector shall be equipped with a shutter or equivalent mechanism that allows the detector
array to be blocked from the light source in order to perform a “dark” measurement of electronic noise
level.
6.4.3 The detector shall be equipped with a flow cell capable of being heated to at least 275 °C.
6.4.4 The detector shall have an independently controlled makeup gas capability, capable of providing
up to 5 ml/min additional flow of nitrogen, helium, or argon to the flow cell.
6.5 Data processing system, capable of storing and processing absorbance scan data and
corresponding time.
6.5.1 Data processing system shall include a database library of vacuum ultraviolet reference spectra,
compound class information, carbon number, density, and approximate retention index (RI) values. Data
processing system shall also store RRFs for each hydrocarbon class in addition to RRFs for individually
reported compounds.
6.5.2 Data processing system shall be capable of implementing equations and fit procedures that result
in deconvolution of absorbance spectra that contain contributions from multiple species.
6.5.3 Data processing system shall be capable of binning and storing response contributions from each
deconvolution analysis and reporting a combined total response at the end of the analysis.
6.5.4 Data processing system shall be capable of implementing equations to convert response areas to
mass fraction % (m/m) and further convert mass fraction % (m/m) to volume fraction % (V/V).
7 Sampling
Unless otherwise specified in the commodity specification, samples shall be taken as described in
EN ISO 3170 or EN ISO 3171.
NOTE National fuel specification standards or legal requirements for the sampling of automotive petrol can
apply.
Samples should be kept refrigerated at approximately 4 °C until ready to be analysed.
8 Preparation of apparatus
8.1 Ensure that all gas connections are properly made, without leaks.
8.2 Install oxygen, moisture, and hydrocarbon filters (6.2) in gas lines upstream of GC and detector.
Maintain gas filters as instructed by manufacturer.
8.3 Install the 30 m column in the GC inlet. Condition the column according to the column
manufacturer’s recommendations prior to connecting to the transfer line of the detector.
8.4 Perform maintenance on the GC as suggested by manufacturer, such as replacing septum and liner.
8.5 Configure the injector, carrier gas (5.2), and other GC parameters according to Table 6.
8.6 Ensure that the deuterium lamp has been turned on and allowed to warm up for at least 30 min
before acquiring data. This warmup period can be used in lieu of the first solvent test sample in 8.7. A
blank run at the beginning of any sequence allows adequate lamp warmup time.
8.7 Inject the solvent test sample defined in 5.4 and run the GC-VUV apparatus through a full oven ramp
and cool-down cycle. Repeat this step. The purpose of this step is to recondition the column by eluting
any accumulation of water. Water accumulation may also be minimized by maintaining the GC oven
temperature above 100 °C during idle periods.
8.8 Assess the baseline. The average absorbance value (125 nm to 240 nm) of the last 1,0 min section
of the baseline at the end of the oven ramp should be no more than ± 0,003 5 AU of the average value
(125 nm to 240 nm) of the initial 1,0 to 2,0 min range.
9 Calibration
9.1 On installation of GC-VUV apparatus, after significant maintenance of GC-VUV apparatus, or after a
significant method change, establish a retention index file. Run the retention time standard (5.5) using
the same flow conditions and oven ramp profile as measured samples (see Table 6 for recommended run
conditions). Record the retention times of iC4, C4, iC5, and C5 through C15 linear alkanes. These will serve
as retention time markers.
Significant method changes include changing the GC, column type, make-up gas pressure, or oven ramp
profile. Significant maintenance of the GC-VUV apparatus includes changing or trimming the analytical
column.
9.2 A list of retention times and retention indices for the branched and linear alkanes is used to
estimate elution times of other compounds in the VUV library according to an interpolation scheme. The
retention index scheme sets the linear alkane retention indices to multiples of 100 according to carbon
number: butane RI = 400, pentane RI = 500, etc.
Each compound entry in the VUV library shall have an associated retention index generated using the
same RI scheme. The RI values for non-polar capillary chromatography found in the literature or other
ASTM methods, such as ASTM D6730 [3], may be used.
Once updated, the same retention index file is used for all subsequent automotive spark-ignition fuel
measurements until the next modification or maintenance of the GC-VUV instrumentation.
9.3 The conversion from response areas to percent mass uses class-based or compound-specific RRFs.
The RRFs account for the differing areal response per unit mass for the various hydrocarbon classes.
9.4 The response area, in absorbance units, is the sum of response over all scans within a time interval
over the 125 nm to 240 nm range. The time interval is defined by the scan rate (see Table 6).
9.5 The response factors are relative to the response of methane, which is taken to have a RRF of 1,000.
9.6 RRF(s) vary between compounds within a hydrocarbon class and also vary between hydrocarbon
classes – see Table 4 for RRF ranges and Annex B for further details. RRFs for speciated compounds are
invariable – see Table 5. The RRF(s) used within each time interval are fixed and invariable and are
determined by the defined software algorithms.
Table 4 — RRFs for bulk hydrocarbon classes
Hydrocarbon class RRF range
Saturates 0,653 - 1,000
Olefin 0,330 - 0,501
C Aromatics 0,204 - 0,360
9+
Table 5 — RRFs for specific individual compounds
Compound RRF
Methanol 1,221
Ethanol 0,957
Benzene 0,244
Toluene 0,252
Ethylbenzene 0,270
Xylenes 0,270
MTBE 0,852
ETBE 0,830
TAME 0,917
TAEE 0,853
10 Pre-measurement validation
10.1 Before proceeding with measurements or after a significant change or maintenance of the GC-VUV
system, the procedures in Clause 9 shall have been completed, and a retention index file generated or
verified following the procedure in 9.1 and 9.2.
10.2 Analyse the system validation mixture (see 5.6)
...