SIST EN 12916:2019

SLOVENSKI STANDARD
oSIST prEN 12916:2017
01-julij-2017
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Petroleum products - Determination of aromatic hydrocarbon types in middle distillates -
High performance liquid chromatography method with refractive index detection
Mineralölerzeugnisse - Bestimmung von aromatischen Kohlenwasserstoffgruppen in
Mitteldestillaten - Hochleistungsflüssigkeitschromatographie-Verfahren mit Brechzahl-
Detektion
Produits pétroliers - Détermination des familles d'hydrocarbures dans les distillats
moyens - Méthode par chromatographie liquide à haute performance avec détection par
réfractométrie différentielle
Ta slovenski standard je istoveten z: prEN 12916
ICS:
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
75.080 Naftni proizvodi na splošno Petroleum products in
general
oSIST prEN 12916:2017 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 12916:2017

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oSIST prEN 12916:2017


DRAFT
EUROPEAN STANDARD
prEN 12916
NORME EUROPÉENNE

EUROPÄISCHE NORM

June 2017
ICS 75.080 Will supersede EN 12916:2016
English Version

Petroleum products - Determination of aromatic
hydrocarbon types in middle distillates - High
performance liquid chromatography method with
refractive index detection
Produits pétroliers - Détermination des familles Mineralölerzeugnisse - Bestimmung von aromatischen
d'hydrocarbures dans les distillats moyens - Méthode Kohlenwasserstoffgruppen in Mitteldestillaten -
par chromatographie liquide à haute performance avec Hochleistungsflüssigkeitschromatographie-Verfahren
détection par réfractométrie différentielle mit Brechzahl-Detektion
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 19.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12916:2017 E
worldwide for CEN national Members.

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Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 5
4 Principle . 6
5 Reagents and materials . 6
6 Apparatus . 7
7 Sampling . 8
8 Apparatus preparation . 8
9 Calibration . 11
10 Procedure. 12
10.1 Procedure A for products with an expected concentration up to 30 % (V/V) . 12
10.2 Procedure B for products with an expected low concentration up to 7 % . 13
10.3 Procedure A and B continuation . 13
11 Calculation . 15
11.1 Retention times . 15
11.2 Column resolution . 15
11.3 Cut times . 15
11.4 Aromatic hydrocarbons type content . 16
11.5 Polycyclic and total aromatic hydrocarbons content . 16
12 Expression of results . 16
13 Precision . 16
13.1 General . 16
13.2 Repeatability, r . 16
13.3 Reproducibility, R . 17
14 Test report . 17
Annex A (informative) Column selection and use . 18
Annex B (informative) Practical instructions for paraffinic diesel fuel samples . 19
Bibliography . 20
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European foreword
This document (prEN 12916:2017) 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 document is currently submitted to the CEN Enquiry.
This document will supersede EN 12916:2016.
Major change compared to the previous version is the addition of a method for the analysis of very low
contents of aromatics. The method now comprises two procedures, A and B. Procedure A covers
conventional diesel fuels and other distillates. Procedure B is set up for paraffinic diesel fuels which do
not require a dilution step and column backflush. Both procedures have a separate precision statement.
Additionally, the required accuracy of the mass of the system calibration standards 1 and 2 was
increased from 0,001 g to 0,000 1 g.
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1 Scope
This European Standard specifies a test method for the determination of the content of mono-aromatic,
di-aromatic and tri+-aromatic hydrocarbons in Diesel fuels, paraffinic Diesel fuels and petroleum
distillates.
This European Standard defines two procedures, A and B.
Procedure A is applicable to diesel fuels that may contain fatty acid methyl esters (FAME) up to
30 % (V/V) and petroleum distillates in the boiling range from 150 °C to 400 °C.
Procedure B is applicable to paraffinic Diesel fuels with up to 7 % (V/V) FAME. This procedure does not
contain a dilution of the sample in order to determine the low levels of aromatic components in these
fuels.
The polycyclic aromatic hydrocarbons content is calculated from the sum of di-aromatic and tri+-
aromatic hydrocarbons and the total content of aromatic compounds is calculated from the sum of the
individual aromatic hydrocarbon types.
Compounds containing sulfur, nitrogen and oxygen can interfere in the determination; mono-alkenes do
not interfere, but conjugated di-alkenes and poly-alkenes, if present, can do so.
NOTE 1 For the purpose of this European Standard, the terms “% (m/m)” and “% (V/V)” are used to represent
the mass fraction and the volume fraction of a material respectively.
NOTE 2 By convention, the aromatic hydrocarbon types are defined on the basis of their elution characteristics
from the specified liquid chromatography column relative to model aromatic compounds. Their quantification is
performed using an external calibration with a single aromatic compound for each of them, which may or may not
be representative of the aromatics present in the sample. Alternative techniques and test methods may classify
and quantify individual aromatic hydrocarbon types differently.
WARNING — The use of this standard can involve hazardous materials, operations and equipment. This
standard does not purport to address all of the safety problems associated with its use. It is the
responsibility of users of this standard to take appropriate measures to ensure the safety and health of
personnel prior to application of the standard, and fulfil statutory and regulatory requirements for this
purpose.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 14214, Liquid petroleum products — Fatty acid methyl esters (FAME) for use in diesel engines and
heating applications — Requirements and test methods
EN ISO 1042, Laboratory glassware — One-mark volumetric flasks (ISO 1042)
EN ISO 3170, Petroleum liquids — Manual sampling (ISO 3170)
EN ISO 3171, Petroleum liquids — Automatic pipeline sampling (ISO 3171)
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
non-aromatic hydrocarbon
compound having a shorter retention time on the specified polar column than the majority of mono-
aromatic hydrocarbons
3.2
mono-aromatic hydrocarbon
MAH
compound having a longer retention time on the specified polar column than the majority of non-
aromatic hydrocarbons, but a shorter retention time than the majority of di-aromatic hydrocarbons
3.3
di-aromatic hydrocarbon
DAH
compound having a longer retention time on the specified polar column than the majority of mono-
aromatic hydrocarbons, but a shorter retention time than the majority of tri+-aromatic hydrocarbons
3.4
tri+-aromatic hydrocarbon
T+AH
compound having a longer retention time on the specified polar column than the majority of di-
aromatic hydrocarbons, but a shorter retention time than chrysene
3.5
polycyclic aromatic hydrocarbon
POLY-AH
sum of the di-aromatic hydrocarbons and tri+-aromatic hydrocarbons
3.6
total aromatic hydrocarbon
sum of the mono-aromatic hydrocarbons, di-aromatic hydrocarbons and tri+-aromatic hydrocarbons
Note 1 to entry: Published and unpublished data indicate that the major constituents for each hydrocarbon type
may include:
a) non-aromatic hydrocarbons: acyclic and cyclic alkanes (paraffins and naphthenes), mono-alkenes (if
present),
b) MAHs: benzenes, tetralins, indanes and higher naphthenobenzenes (e.g. octahydrophenanthrenes),
thiophenes, styrenes, conjugated polyalkenes,
c) DAHs: naphthalenes, biphenyls, indenes, fluorenes, acenaphthenes, benzothiophenes and dibenzothiophenes,
d) T+AHs: phenanthrenes, pyrenes, fluoranthenes, chrysenes, triphenylenes, benzanthracenes.
3.7
fatty acid methyl ester
FAME
mixture of fatty acid methyl esters derived from vegetable oil or animal fats and complying to the
specification defined in EN 14214
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4 Principle
A known mass of sample is taken and a fixed volume of this sample is injected into a high performance
liquid chromatograph fitted with a polar column. Conventional Diesel Fuels with a concentration of up
to 30 % (V/V) need to be diluted with heptane (Procedure A). Paraffinic Diesel fuels are injected neat
(Procedure B).
This column has little affinity for non-aromatic hydrocarbons, while exhibiting a strong selectivity for
aromatic hydrocarbons. As a result of this selectivity, the aromatic hydrocarbons are separated from
the non-aromatic hydrocarbons and into distinct bands according to their ring structure, i.e. MAH, DAH
and T+AH compounds.
The column is connected to a refractive index detector which detects the components as they elute from
the column. The electronic signal from the detector is continually monitored by a data processor. The
amplitudes of the signals from the aromatics in the sample are compared with those obtained from
calibration standards in order to calculate the mass fraction of MAHs, DAHs and T+AHs in the sample.
The sum of the DAHs and T+AHs mass fractions is reported as the mass fraction of POLY-AH, and the
sum of the MAHs, DAHs and T+AHs mass fractions is reported as the mass fraction of total aromatic
hydrocarbons.
When following Procedure A, the column may be backflushed after the aromatics have eluted from the
column to allow any remaining components such as FAME to elute in a backflush peak. This will allow
for a better cleaning of the column but care should be taken as it can affect the lifetime of the column.
5 Reagents and materials
5.1 General
The highest purity reagents and materials available should be used; those required to be of high
performance liquid chromatography (HPLC) grade are commercially available from major suppliers.
5.2 Cyclohexane, of 99 % (m/m) minimum purity (CAS registry number 110-82-7).
NOTE Cyclohexane can contain benzene as an impurity.
5.3 Heptane, HPLC analytical grade, as the mobile phase (CAS registry number 142-82-5).
Batch to batch variation of the solvent water content, viscosity, refractive index, and purity can cause
unpredictable column behaviour. Drying (for example, by standing over activated molecular sieve type
5A) and filtering the mobile phase can help reducing the effect of trace impurities present in the solvent.
It is recommended practice to de-gas the mobile phase before use; this can be done conveniently online
or off-line by helium sparging, vacuum degassing or ultrasonic agitation. A failure to de-gas the mobile
phase can lead to negative peaks.
5.4 1-Phenyldodecane, of 98 % (m/m) minimum purity (CAS registry number 123-01-3).
5.5 1,2-Dimethylbenzene (o-xylene), of 98 % (m/m) minimum purity (CAS registry number 95-47-
6).
5.6 Hexamethylbenzene, of 98 % (m/m) minimum purity (CAS registry number 87-85-4).
5.7 Naphthalene, of 98 % (m/m) minimum purity (CAS registry number 91-20-3).
5.8 Fluorene, of 98 % (m/m) minimum purity (CAS registry number 86-73-7).
5.9 Phenanthrene, of 98 % (m/m) minimum purity (CAS registry number 85-01-8).
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5.10 Dibenzothiophene, of 95 % (m/m) minimum purity (CAS registry number 132-65-0).
5.11 9-Methylanthracene, of 95 % (m/m) minimum purity (CAS registry number 779-02-2).
5.12 Chrysene, of 95 % (m/m) minimum purity (CAS registry number 218-01-9).
5.13 FAME, compliant to EN 14214.
WARNING — Protective gloves should be worn when handling aromatic compounds.
6 Apparatus
6.1 Liquid chromatograph, consisting of a high performance instrument capable of pumping the
mobile phase at flow rates from 0,5 ml/min to 1,5 ml/min, with a precision better than 0,5 % and a
pulsation of < 1 % full scale deflection under the test conditions described in Clause 8.
6.2 Sample injection system, capable of nominally injecting 10 μl of sample solution with a
repeatability better than 1 %.
Equal and constant volumes of the calibration and sample solutions are injected into the
chromatograph. Both manual and automatic sample injection systems, using either complete or partial
filling of the sample loop, can meet these repeatability requirements when used correctly. When using
the partial filling mode, it is recommended that the injection volume is less than half the total loop
volume. For complete filling of the loop, best results are obtained by overfilling the loop at least six
times.
The repeatability of the injection system can be checked by comparing peak areas from at least four
injections of the system calibration standard (see 8.3).
Sample and calibration injection volumes different from 10 μl (typically in the range 3 μl to 20 μl) may
be used provided they meet the requirements for injection repeatability, refractive index sensitivity and
linearity (see 9.4), and column resolution (see 8.9).
6.3 Sample filter, if required (see 10.1), consisting of a microfilter of porosity 0,45 μm or less,
chemically inert towards hydrocarbon solvents, for the removal of particulate matter from the sample
solutions.
NOTE Polytetrafluorethylen (PTFE) filters have been found to be suitable.
6.4 Column system, consisting of a stainless steel HPLC column(s) packed with a commercial 3 μm,
5 μm or 10 μm amino-bonded (or amino/cyano-bonded) silica stationary phase meeting the resolution
requirements given in 8.6, 8.7, 8.9 and 8.11 . See Annex A for guidance on the selection and use of
suitable column systems.
6.5 Temperature controls, for different parts of the apparatus (column, sample injection system,
solvent, refractive index detector). Maintain the sample injection system at the same temperature as the
sample solution, for the column a heating block or an air-circulating HPLC column oven may be used.
Also, a temperature-controlled laboratory, capable of maintaining a constant temperature in the range
(20 ± 1) °C to (40 ± 1) °C may be used.
The refractive index detector is sensitive to both sudden and gradual changes in the temperature of the
eluent. All necessary precautions should be taken to establish constant temperature conditions
throughout the liquid chromatograph system. The temperature should be optimized depending on the
stationary phase.
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6.6 Refractive index detector, capable of being operated over the refractive index range 1,3 to 1,6
and giving a linear response over the calibration ranges with a suitable output signal for the data
system.
If the detector is equipped with a device for independent temperature control, it is recommended that it
is set at the same temperature as the column oven.
6.7 Computer or computing integrator, compatible with the refractive index detector, having a
minimum sampling rate of 1 Hz and capable of peak area and retention time measurements. It shall also
have minimum capabilities for post-analysis data processing such as baseline correction and re-
integration.
The ability to perform automatic peak detection and identification and to calculate sample
concentrations from peak area measurements is recommended, but is not essential.
6.8 Volumetric flasks, 10 ml and 100 ml capacity, conforming to grade A of EN ISO 1042.
6.9 Analytical balance, with an accuracy of ± 0,000 1 g.
7 Sampling
Unless otherwise specified in the commodity specification, samples shall be taken as described in
EN ISO 3170 or EN ISO 3171 and/or in accordance with the requirements of national standards or
regulations for the sampling of the product under test.
Paraffinic diesel fuel samples analysed according to Procedure B require specific storage conditions:
— A storage temperature of 19 °C ± 5 °C shall be maintained. If for some reason, the samples have
been exposed to temperatures above 25 °C for a long period during storage or in custody (that you
are aware of), this shall be reported.
— At least 24 h before a test the blend shall be placed at ambient temperature.
— When a portion of the sample is removed for use in a test, air admitted to the container shall be
replaced by nitrogen or helium before closing the container tight.
8 Apparatus preparation
8.1 Ensure that the equipment and any sample distribution system is clean and dry before use. Make
sure that the equipment for handling or testing the sample is not sensitive to FAME. Recommended
materials are Polytetrafluoroethylene, Viton® and Nylon.
8.2 Set up the liquid chromatograph (6.1), sample injection system (6.2), column (6.4), refractive
index detector (6.6) and computing integrator (6.7) as in Figure 1 and in accordance with the
manufacturer’s manuals. If a column oven is used (6.5), install the HPLC column in the column oven.
Maintain the sample injection system at the same temperature as the sample solution; in most cases this
should be at room temperature.
Regular maintenance of the liquid chromatograph and its components is important and thus
recommended to ensure consistent performance. Leakages and partial blockage of filters, frits, injector
needles and valve rotors can produce flow rate inconsistencies and poor injector repeatability.
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Key
1 pump 4 column
2 injection device 5 refractive index detector
3 oven 6 data acquisition system
Figure 1 — Diagrammatic representation of a liquid chromatograph
8.3 Adjust the flow rate of the mobile phase to a constant between 0,8 ml/min and 1,2 ml/min and
ensure the reference cell of the refractive index detector is full of mobile phase. Allow the temperature
of the column and of the refractive index detector, if it is equipped with temperature control, to
stabilize.
In order to minimize instrument drift, the reference cell of the detector should be filled with mobile
phase, either by flushing mobile phase through the reference cell immediately prior to the analysis, and
then isolating the reference cell to prevent evaporation, or by compensating for evaporation by
supplying a steady flow of mobile phase through the reference cell. The flow should be optimized so
that cell mismatch due to drying-out (reference cell) or temperature or pressure gradients (reference or
analysis cells, depending the type of detector) are minimized; with some detectors this can be
accomplished using a mobile phase flow through the reference cell of one tenth of that through the
analysis cell.
8.4 Prepare into a 100 ml volumetric flask a system calibration standard 1 (SCS1) by weighing to the
nearest 0,0001 g:
— (1,0 ± 0,1) g cyclohexane (5.2),
— (0,1 ± 0,01) g 1-phenyldodecane (5.4),
— (0,5 ± 0,05) g 1,2-dimethylbenzene (5.5),
— (0,1 ± 0,01) g hexamethylbenzene (5.6),
— (0,1 ± 0,01) g naphthalene (5.7),
— (0,05 ± 0,005) g dibenzothiophene (5.10), and
— (0,05 ± 0,005) g 9-methylanthracene (5.11).
Place the flask and its contents into an ultrasonic bath until a visual examination shows that all the
components have dissolved into the 1,2-dimethylbenzene/cyclohexane mixture. Remove from the
ultrasonic bath and make up to the mark with heptane.
The SCS1 may be kept for at least one year if stored in a tightly stoppered bottle in a cool dark place (for
example in a refrigerator).
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8.5 Prepare into a 100 ml volumetric flask a system calibration standard 2 (SCS2) by weighing to the
nearest 0,000 1 g, (0,4 ± 0,1) g FAME (5.13) and (0,04 ± 0,01) g chrysene (5.12) and making up to the
mark with heptane (5.3). Keep the solution into an ultrasonic bath at 35 °C.
Ensure the appearance is homogeneous without deposits of chrysene on the bottom.
NOTE 25 min has been found to be a suitable time for all the components to become dissolved.
The SCS2 may be kept for at least one year if stored in a tightly stoppered bottle in a cool dark place (for
example in a refrigerator).
8.6 When operating conditions are steady, as indicated by a stable horizontal baseline, inject 10 μl of
the SCS1 (8.3). Ensure the baseline drift over the period of the HPLC analysis run is less than 1 % of the
peak height for cyclohexane.
NOTE A baseline drift greater than this indicates problems with the temperature control of the
column/refractive index detector and/or material eluting from the column.
8.7 Ensure the components of the SCS1 are eluted in the order: cyclohexane, phenyldodecane, 1,2-
dimethylbenzene, hexamethylbenzene, naphthalene, dibenzothiophene and 9-methylanthracene.
8.8 Ensure that baseline separation is obtained between all components of the SCS1 (see Figure 2).
8.9 Measure the retention times of the cyclohexane, phenyldodecane, 1,2-dimethylbenzene,
hexamethylbenzene, dibenzothiophene and 9-methylanthracene peaks using the data system.
8.10 Ensure that the resolution between cyclohexane and 1,2-dimethylbenzene is between 5,7 and 10
(see 11.2).
8.11 Calculate the cut times using the equations given in 11.3.
8.12 Ensure the appearance of SCS2 is homogeneous (8.4) and then, inject 10 μl of the SCS2 and check
the chrysene peak elutes just before or together with the first peak of FAME.
Ensure the retention time of chrysene peak be higher than the retention time of 9-methylanthracene
peak.
Test the column with the SCS2 to verify its performances when starting the method with a new column,
after a period of time of inactivity or when samples with FAME should be run.
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Key
1 cyclohexane 5 naphthalene
2 phenyldodecane 6 dibenzothiophene
3 1,2 dimethylbenzene 7 9-methylanthracene
4 hexamethylbenzene
x-axis time (min)
y-axis signal (mV)
Figure 2 — Chromatogram of the system calibration standard SCS1
9 Calibration
9.1 Prepare four calibration standards referenced A, B, C and D at the approximate (but accurately
known) concentrations given in Table 1, by weighing the appropriate materials to the nearest 0,000 1 g
into 100 ml volumetric flasks and making up to the mark with heptane (5.3).
NOTE The calibration standards are viable for at least six months if stored in tightly stoppered containers
(e.g. 100 ml volumetric flasks) in a cool dark place (for example, in a refrigerator).
Table 1 — Concentrations of calibration standard components
Calibration standard 1,2 Dimethylbenzene Fluorene Phenanthrene
g/100 ml g/100 ml g/100 ml
A 4,0 2,0 0,4
B 1,0 1,0 0,2
C 0,25 0,25 0,05
D 0,05 0,02 0,01
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9.2 When operating conditions are steady (see 8.5), inject 10 μl of calibration standard A. Record the
chromatogram and measure the peak areas for each aromatic standard (see Figure 3).
9.3 Repeat 9.2 for each of the other calibration standards B, C and D.
If the peak area for phenanthrene in calibration standard D is too small to be accurately measured,
prepare a new calibration standard, D+, with a higher concentration of phenanthrene, e.g.
0,02 g/100 ml, and repeat 9.2.
9.4 Plot concentrations in g/100 ml against area counts for each aro
...