NORME EUROPÉENNE English Version Automotive fuels - Paraffinic diesel fuel from synthesis or hydrotreatment - Requirements and test methods Carburants pour automobiles - Gazoles paraff
Dyes and markers
The use of dyes or markers is allowed.
Additives
General
To enhance performance quality, the use of safe fuel additives is permitted, provided they are used in appropriate amounts These additives help prevent deterioration in drivability and maintain emissions control durability Additionally, other technical solutions with similar effects may also be utilized.
NOTE Deposit forming tendency test methods suitable for routine control purposes have not yet been identified and developed.
Methylcyclopentadienyl Manganese Tricarbonyl (MMT)
The use of methylcyclopentadienyl manganese tricarbonyl (MMT) necessitates specific labeling requirements (refer to Clause 4) Additionally, the concentration of MMT in paraffinic diesel fuel must not exceed 2 mg of manganese per liter.
2 ) CEN is developing a generic fuel labelling standard, EN 16942 [ 24 ], for this.
EN ISO 2719:2002, Determination of flash point — Pensky-Martens closed cup method (ISO 2719:2002) 1 )
EN ISO 3104:1996, Petroleum products — Transparent and opaque liquids — Determination of kinematic viscosity and calculation of dynamic viscosity (ISO 3104:1994)
EN ISO 3170:2004, Petroleum liquids — Manual sampling (ISO 3170:2004)
EN ISO 3171:1999, Petroleum liquids — Automatic pipeline sampling (ISO 3171:1988)
EN ISO 3405:2011, Petroleum products — Determination of distillation characteristics at atmospheric pressure (ISO 3405:2011)
EN ISO 3675:1998, Crude petroleum and liquid petroleum products — Laboratory determination of density - Hydrometer method (ISO 3675:1998)
EN ISO 3924:2010, Petroleum products — Determination of boiling range distribution — Gas chromatography method (ISO 3924:2010)
EN ISO 4259:2006, Petroleum products — Determination and application of precision data in relation to methods of test (ISO 4259:2006)
EN ISO 5165:1998, Petroleum products — Determination of the ignition quality of diesel fuels — Cetane engine method (ISO 5165:1998)
EN ISO 6245:2002, Petroleum products — Determination of ash (ISO 6245:2001)
EN ISO 10370:2014, Petroleum products — Determination of carbon residue — Micro method
EN ISO 12156-1:2016, Diesel fuel — Assessment of lubricity using the high-frequency reciprocating rig
(HFRR) — Part 1: Test method (ISO 12156-1:2016)
EN ISO 12185:1996, Crude petroleum and petroleum products — Determination of density — Oscillating
EN ISO 12205:1996, Petroleum products — Determination of the oxidation stability of middle-distillate fuels (ISO 12205:1995)
EN ISO 12937:2000, Petroleum products — Determination of water — Coulometric Karl Fischer titration method (ISO 12937:2000)
EN ISO 13759:1996, Petroleum products — Determination of alkyl nitrate in diesel fuels — Spectrometric method (ISO 13759:1996)
EN ISO 20846:2011, Petroleum products — Determination of sulfur content of automotive fuels —
EN ISO 20884:2011, Petroleum products — Determination of sulfur content of automotive fuels —
Wavelength-dispersive X-ray fluorescence spectrometry (ISO 20884:2011)
Samples must be collected following the guidelines outlined in EN ISO 3170 or EN ISO 3171, as well as any applicable national standards or regulations for automotive diesel fuel sampling Detailed national requirements should be explicitly stated or referenced in a National Annex to this European Standard if it is implemented at the national level.
Given the sensitivity of certain test methods mentioned, it is crucial to adhere to the guidance on sampling containers outlined in the test method standard.
Dispensing pumps for paraffinic diesel fuel must display information that complies with national standards or regulations for automotive diesel fuel marking The dimensions of these markings should adhere to specified requirements, which will be detailed or referenced in a National Annex to the relevant European Standard.
Paraffinic diesel fuel shall be distinguished from other diesel fuel by a dedicated marking 2 )
Labels for paraffinic diesel with metallic additives must be clearly visible and easily legible at all consumer access points They should state "Contains metallic additives" in the national language(s) as specified in the National Annex Additionally, it is advisable to include a warning on dispensing pumps in the national language stating, "Not suitable for all vehicles; consult vehicle manufacturer or manual before use."
5 Requirements and test methods 5.1Dyes and markers
The use of dyes or markers is allowed
To enhance performance quality, the use of safe fuel additives is permitted, provided they are used in appropriate amounts These additives help prevent deterioration in drivability and maintain emissions control durability Additionally, other technical solutions with similar effects may also be utilized.
NOTE Deposit forming tendency test methods suitable for routine control purposes have not yet been identified and developed
Methylcyclopentadienyl manganese tricarbonyl (MMT) requires specific labeling as outlined in Clause 4 Additionally, the concentration of MMT in paraffinic diesel fuel must not exceed 2 mg of manganese per liter.
2 ) CEN is developing a generic fuel labelling standard, EN 16942 [ 24 ], for this.
Fatty acid methyl ester (FAME)
Paraffinic diesel fuel may contain up to 7,0 % (V/V) of FAME complying with EN 14214:2012+A1:2014, in which case the climate-dependent requirements set out in EN 14214:2012+A1:2014, 5.4.2 do not apply
NOTE A suitable method for the separation and identification of FAME is given in EN 14331 [4].
Cavitation prevention
Fuels with an initial boiling point (IBP) below 160 °C, as determined by EN ISO 3405, may impose a risk of cavitation damage
The IBP of paraffinic diesel fuels shall be measured and reported using EN ISO 3405
NOTE This issue is further being studied by CEN For explanation on the risks, see CEN/TR 16389 [2].
Seizure protection
Paraffinic fuels have been effectively used for over 12 years without reports of lubricity issues However, evidence suggests that diesel fuel with high paraffin content may not adequately safeguard fuel system components from seizure While the lubricity requirements outlined in Table 1 provide protection against wear, they do not guarantee protection against seizure.
Appropriate seizure protection shall be provided by using suitable fuel additives or by blending of minimum 2 % (V/V) of FAME
NOTE For further information, see Annex A.
Generally applicable requirements and related test methods
Paraffinic diesel fuel must meet the specified limits outlined in Table 1 when evaluated using the methods described, ensuring compliance with either Class A (high cetane paraffinic diesel fuel) or Class B standards.
(normal cetane paraffinic diesel fuel)
NOTE 1 All values in Table 1 meet the requirements of the European Fuels Directive 98/70/EC [5], including
Amendments 2003/17/EC [6], 2009/30/EC [7] and 2014/77/EU [8]
NOTE 2 For further clarification of the Classes, see CEN/TR 16389 [2]
5.6.2 The limiting value for the cetane number given in Table 1 is based on product prior to addition of cetane improver
The correlation equation specified in EN 15195:2014, Clause 12, must be utilized, as it is crucial for accurate results Alternative test methods, such as EN 16715 and ASTM D6890, offer a different correlation equation designed for low ignition delay (high cetane) diesel fuels, but these should be avoided due to the lack of a precision statement It is essential to exercise caution with automated equipment to prevent the default application of this alternative equation.
Table 1 — Generally applicable requirements and test methods
Property Unit Limits Class A Limits Class B Test method a minimum maximum minimum maximum (See Clause 2)
Density at 15 °C kg/m 3 765,0 800,0 780,0 810,0 EN ISO 3675 d
Flash point °C Above 55,0 – Above 55,0 – EN ISO 2719
Viscosity at 40 °C mm 2 /s 2,000 4,500 2,000 4,500 EN ISO 3104
(wsd) at 60 °C f àm – 460 – 460 EN ISO 12156-1
Sulfur content mg/kg – 5,0 – 5,0 EN ISO 20846 j
Water content mg/kg – 200 – 200 EN ISO 12937
Total contamination mg/kg – 24 – 24 EN 12662 l
(3 h at 50 °C) rating class 1 class 1 EN ISO 2160
The oxidation stability of paraffinic diesel fuels is measured in g/m³, with a standard of 25 according to EN ISO 12205 All test methods are applicable without issues, as detailed in Annex B For accurate results, it is essential to apply the correct correlation equation and make necessary corrections as outlined in Annex D The limits are defined by the EN ISO 3405 scale, and results from EN ISO 3924 must be converted per EN ISO 3924:2010, Annex A FAME must comply with EN 14214 standards, and total aromatics content includes polycyclic aromatic hydrocarbons, which must meet legal limits If filtration exceeds 30 minutes, the test is deemed incomplete, indicating non-compliance with the European Standard, particularly for paraffinic diesel fuel containing more than 2% (V/V) FAME.
5.3Fatty acid methyl ester (FAME)
Paraffinic diesel fuel may contain up to 7,0 % (V/V) of FAME complying with EN 14214:2012+A1:2014, in which case the climate-dependent requirements set out in EN 14214:2012+A1:2014, 5.4.2 do not apply
NOTE A suitable method for the separation and identification of FAME is given in EN 14331 [4]
Fuels with an initial boiling point (IBP) below 160 °C, as determined by EN ISO 3405, may impose a risk of cavitation damage
The IBP of paraffinic diesel fuels shall be measured and reported using EN ISO 3405
NOTE This issue is further being studied by CEN For explanation on the risks, see CEN/TR 16389 [2]
Paraffinic fuels have been successfully used for over 12 years without reports of insufficient lubricity However, there are concerns that diesel fuel with high paraffin content may not adequately protect fuel system components from seizure While the lubricity requirements outlined in Table 1 provide protection against wear, they do not guarantee protection against seizure.
Appropriate seizure protection shall be provided by using suitable fuel additives or by blending of minimum 2 % (V/V) of FAME
NOTE For further information, see Annex A
5.6 Generally applicable requirements and related test methods
Paraffinic diesel fuel must meet the specified limits outlined in Table 1 when tested using the methods described, ensuring compliance for either Class A (high cetane paraffinic diesel fuel) or Class B.
(normal cetane paraffinic diesel fuel)
NOTE 1 All values in Table 1 meet the requirements of the European Fuels Directive 98/70/EC [5], including
Amendments 2003/17/EC [6], 2009/30/EC [7] and 2014/77/EU [8]
NOTE 2 For further clarification of the Classes, see CEN/TR 16389 [2]
5.6.2 The limiting value for the cetane number given in Table 1 is based on product prior to addition of cetane improver
The correlation equation specified in EN 15195:2014, Clause 12, must be utilized, as it is crucial for accurate results Alternative test methods, such as EN 16715 and ASTM D6890, offer a different correlation equation designed for low ignition delay (high cetane) diesel fuels; however, these should be avoided due to the lack of a precision statement It is essential to exercise caution with automated equipment to prevent the default application of this alternative equation.
Table 1 — Generally applicable requirements and test methods
Property Unit Limits Class A Limits Class B Test method a minimum maximum minimum maximum (See Clause 2)
Density at 15 °C kg/m 3 765,0 800,0 780,0 810,0 EN ISO 3675 d
Flash point °C Above 55,0 – Above 55,0 – EN ISO 2719
Viscosity at 40 °C mm 2 /s 2,000 4,500 2,000 4,500 EN ISO 3104
(wsd) at 60 °C f àm – 460 – 460 EN ISO 12156-1
Sulfur content mg/kg – 5,0 – 5,0 EN ISO 20846 j
Water content mg/kg – 200 – 200 EN ISO 12937
Total contamination mg/kg – 24 – 24 EN 12662 l
(3 h at 50 °C) rating class 1 class 1 EN ISO 2160
The oxidation stability of paraffinic diesel fuels is measured in g/m³, with a standard of 25 according to EN ISO 12205 All test methods are applicable without issues, as detailed in Annex B For accurate results, it is essential to apply the correct correlation equation and make necessary corrections as outlined in the relevant sections The limits are defined on the EN ISO 3405 scale, and results from EN ISO 3924 must be converted per EN ISO 3924:2010, Annex A FAME must comply with EN 14214 standards, and total aromatics content includes polycyclic aromatic hydrocarbons, ensuring compliance with legal limits If filtration time exceeds 30 minutes, the test should be halted, and the result reported as incomplete, indicating non-compliance with the European Standard Additionally, for paraffinic diesel fuel containing more than 2% (V/V) FAME, there are extra requirements to consider.
The carbon residue limit specified in Table 1 applies to the product before the addition of any ignition improver If the finished fuel available in the market shows a carbon residue value that exceeds this limit, it raises concerns regarding its quality.
EN ISO 13759 serves as a key indicator for detecting nitrate-containing compounds If an ignition improver is identified, the carbon residue limit for the tested product is not applicable Manufacturers must still adhere to the maximum carbon residue requirement of 0.30% (m/m) before any additives are introduced.
5.6.5 Tests have shown that EN 15751 is applicable for paraffinic fuels with a FAME content above
2 % (V/V) covered under this European Standard Paraffinic diesel fuels can have an induction period above 48 h thus exceeding the maximum measuring time considered for the precision statement in
EN 15751 However, even taking into account that the precision above the 48 h can get worse, such fuels are considered having a oxidation stability significantly above the limit set in this European
5.6.6 Paraffinic diesel fuel shall be free from any adulterant or contaminant that may render the fuel unacceptable for use in diesel engine vehicles
NOTE 1 For further information on preventing contamination by water or sediment that can occur in the supply chain, it is advisable to check CEN/TR 15367–1 [11]
Any intentional addition of non-paraffinic material, other than additives and dyes or markers, is not allowed
NOTE 2 Paraffinic diesel fuel before blending with FAME is expected to contain more than 98,5 % (m/m) of paraffinic hydrocarbons
Currently, there is no available test method for determining the paraffinic hydrocarbon content, as noted in this European Standard Consequently, the total aromatics are restricted as outlined in Table 1 For further details, refer to CEN/TR 16389 [2].
Climate dependent requirements and related test methods
For climate-dependent requirements, options are available to establish seasonal grades on a national level Specifically, six CFPP (cold filter plugging point) grades are designated for temperate climates, while five distinct classes are provided for arctic or severe winter climates.
Paraffinic diesel fuel must meet the specified limits outlined in Tables 2 and 3, which pertain to temperate and arctic or severe winter climates, respectively.
Table 2 — Climate-related requirements and test methods - Temperate climates
Property Unit Limits Test method a
Grade A Grade B Grade C Grade D Grade E Grade F (see Clause 2)
EN 16329 a See also 5.8.1 b See also 5.8.6
When implementing this European Standard, each country must specify requirements for summer and winter grades in a National Annex, and may also include intermediate or regional grades supported by national meteorological data It is highly recommended to align these grades with those in the National Annex to EN 590, which provides comprehensive requirements related to the standards.
Tables 2 and 3 of this document
Table 3 — Climate-related requirements and test methods - Arctic or severe winter climates
Property Units Limits Test method a class
Viscosity at 40 °C mm 2 /s, min mm 2 /s, max 1,500
According to EN ISO 3405, the maximum recovery at 180 °C is set at 10.0% (V/V), while EN ISO 3924 specifies a minimum recovery of 95.0% (V/V) at 340 °C For further details, refer to sections 5.8.1, 5.8.4, and 5.8.6 It is important to note that the limits are based on the EN ISO 3405 scale, and EN ISO 3924 provides guidance for converting to EN ISO 3405-equivalent data.
Precision and dispute
This document outlines test methods that include a precision statement based on standard diesel fuel matrices In the event of a dispute, the resolution procedures and result interpretation, as specified in EN ISO 4259, will be applied If precision data varies for paraffinic diesel fuels listed in Annex B, the precision data from Annex B will take precedence.
The test method for total aromatics content outlined in Annex C has not been fully evaluated at all necessary levels; however, an initial feasibility study based on real-world experience suggests that the method is indeed applicable.
NOTE It is the intention to include data of a pending Round Robin in future publications of this document
In the event of a dispute regarding cetane number, EN 15195 should be referenced Alternative methods for determining cetane number may be employed, as long as they are based on a recognized method series and possess a valid precision statement in accordance with EN ISO 4259, ensuring precision comparable to the referenced method Additionally, the test results from alternative methods must demonstrate a clear correlation with those obtained from the referenced method.
5.8.4 In cases of dispute concerning distillation, EN ISO 3405 shall be used
5.8.5 In cases of dispute concerning sulfur, EN ISO 20846 shall be used
5.8.6 In cases of dispute concerning CFPP, EN 116 shall be used
5.8.7 In cases of dispute concerning density, EN ISO 12185 shall be used
The carbon residue limit specified in Table 1 applies to the product before the addition of any ignition improver If the finished fuel available in the market exceeds this limit, it raises concerns regarding its quality.
EN ISO 13759 serves as a key indicator for detecting nitrate-containing compounds If an ignition improver is confirmed to be present, the carbon residue limit for the tested product is not applicable Manufacturers must still adhere to the maximum carbon residue requirement of 0.30% (m/m) before any additives are introduced.
5.6.5 Tests have shown that EN 15751 is applicable for paraffinic fuels with a FAME content above
2 % (V/V) covered under this European Standard Paraffinic diesel fuels can have an induction period above 48 h thus exceeding the maximum measuring time considered for the precision statement in
EN 15751 However, even taking into account that the precision above the 48 h can get worse, such fuels are considered having a oxidation stability significantly above the limit set in this European
5.6.6 Paraffinic diesel fuel shall be free from any adulterant or contaminant that may render the fuel unacceptable for use in diesel engine vehicles
NOTE 1 For further information on preventing contamination by water or sediment that can occur in the supply chain, it is advisable to check CEN/TR 15367–1 [11]
Any intentional addition of non-paraffinic material, other than additives and dyes or markers, is not allowed
NOTE 2 Paraffinic diesel fuel before blending with FAME is expected to contain more than 98,5 % (m/m) of paraffinic hydrocarbons
Currently, there is no established test method for measuring paraffinic hydrocarbon content, as noted in this European Standard Consequently, the total aromatics are restricted as outlined in Table 1 For further details, refer to CEN/TR 16389 [2].
5.7Climate dependent requirements and related test methods
For climate-dependent requirements, options are available to establish seasonal grades on a national level Specifically, there are six CFPP (cold filter plugging point) grades for temperate climates and five distinct classes for arctic or severe winter climates.
Paraffinic diesel fuel must meet the specified limits outlined in Tables 2 and 3, which pertain to temperate and arctic or severe winter climates, respectively.
Table 2 — Climate-related requirements and test methods - Temperate climates
Property Unit Limits Test method a
Grade A Grade B Grade C Grade D Grade E Grade F (see Clause 2)
EN 16329 a See also 5.8.1 b See also 5.8.6
When implementing this European Standard, each country must specify requirements for summer and winter grades in a National Annex, potentially including intermediate or regional grades supported by national meteorological data It is highly recommended to align these grades with those outlined in the National Annex to EN 590, which provides comprehensive requirements related to the standards.
Tables 2 and 3 of this document
Table 3 — Climate-related requirements and test methods - Arctic or severe winter climates
Property Units Limits Test method a class
Viscosity at 40 °C mm 2 /s, min mm 2 /s, max 1,500
The distillation process is governed by EN ISO 3405, which specifies a maximum recovery of 10.0% (V/V) at 180 °C Additionally, EN ISO 3924 outlines that a minimum recovery of 95.0% (V/V) must be achieved at 340 °C For further details, refer to sections 5.8.1, 5.8.4, and 5.8.6, as the limits are based on the EN ISO 3405 scale, with EN ISO 3924 providing guidance for converting to EN ISO 3405-equivalent data.
The test methods outlined in this document include a precision statement based on standard diesel fuel matrices In the event of a dispute, the resolution procedures and result interpretation, as specified in EN ISO 4259, will be applied If precision data varies for paraffinic diesel fuels listed in Annex B, the precision data from Annex B will take precedence.
The test method for total aromatics content outlined in Annex C has not been fully evaluated at all necessary levels; however, an initial feasibility study based on real-world experience suggests that the method is indeed applicable.
NOTE It is the intention to include data of a pending Round Robin in future publications of this document
In the event of a dispute regarding cetane number, EN 15195 should be referenced Alternative methods for determining cetane number may be employed, provided they are based on recognized method series and possess a valid precision statement in accordance with EN ISO 4259, ensuring precision comparable to the referenced method Additionally, the test results from alternative methods must demonstrate a clear correlation with those obtained from the referenced method.
5.8.4 In cases of dispute concerning distillation, EN ISO 3405 shall be used
5.8.5 In cases of dispute concerning sulfur, EN ISO 20846 shall be used
5.8.6 In cases of dispute concerning CFPP, EN 116 shall be used
5.8.7 In cases of dispute concerning density, EN ISO 12185 shall be used
To prevent seizure, it is currently sufficient for fuels to meet a minimum scuffing load of 3,500 g as determined by the SL-BOCLE test Extensive experience with standard diesel fuels indicates that those exceeding this limit provide adequate seizure protection under field conditions Typically, conventional crude oil-based diesel fuels meet this requirement, ensuring effective wear protection, as evidenced by a Wear Scar Diameter (WSD) of the ball not exceeding 460 µm in the HFRR test.
The ASTM standard specification for diesel fuel oils mandates a maximum HFRR wear scar diameter (WSD) of 520 µm and a SL-BOCLE value exceeding 3,100 g to ensure adequate lubricity In contrast, the diesel vehicle fleet in Europe is typically validated for fuels with a maximum HFRR wear scar diameter of 460 µm, which corresponds to a SL-BOCLE value greater than 3,500 g.
Warning
Caution: This procedure may involve hazardous materials, operations, and equipment This Standard does not cover all safety issues related to its use Users are responsible for implementing necessary safety measures to protect personnel and comply with relevant statutory and regulatory requirements before applying the standard.
Scope
This procedure outlines a testing method to measure the levels of mono-aromatic, di-aromatic, and tri-aromatic hydrocarbons in diesel fuels that may include fatty acid methyl esters.
The content of polycyclic aromatic hydrocarbons (PAHs) is determined by adding the amounts of di-aromatic and tri-aromatic hydrocarbons Additionally, the total aromatic compounds are calculated by summing the individual types of aromatic hydrocarbons.
The standard HPLC techniques typically involve a dilution step; however, the method based on EN 12916 has been modified for paraffinic diesel fuels, including those blended with up to 7% (V/V) FAME, to accurately measure very low levels of aromatic components without requiring a dilution step.
Aromatic hydrocarbons are classified based on their elution characteristics from a specific liquid chromatography column in relation to model compounds Their quantification relies on external calibration using a single aromatic compound, which may not accurately represent the actual aromatics in the sample Different techniques and methods may lead to varying classifications and quantifications of individual aromatic hydrocarbon types.
This method has been evaluated through the CEN/TC 19 ILS project, which was funded by the European Commission For more information, please contact the CEN/TC 19 Secretariat.
Terms and definitions
For the purposes of this annex, the following terms and definitions apply
C.3.1 non-aromatic hydrocarbon compound having a shorter retention time on the specified polar column than the majority of mono- aromatic hydrocarbons
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
Di-aromatic hydrocarbons (DAHs) exhibit a longer retention time on a specified polar column compared to most mono-aromatic hydrocarbons, yet they have a shorter retention time than the majority of tri-aromatic hydrocarbons.
C.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
C.3.5 polycyclic aromatic hydrocarbon POLY-AH sum of the di-aromatic hydrocarbons and tri+-aromatic hydrocarbons
C.3.6 total aromatic hydrocarbon sum of the mono-aromatic hydrocarbons, di-aromatic hydrocarbons and tri+-aromatic hydrocarbons
Published and unpublished data reveal that the primary components of various hydrocarbon types include: a) non-aromatic hydrocarbons, which consist of acyclic and cyclic alkanes (paraffins and naphthenes) and potentially mono-alkenes; b) mono-aromatic hydrocarbons (MAHs), characterized by compounds such as benzenes, tetralins, indanes, higher naphthenobenzenes (e.g., octahydrophenanthrenes), thiophenes, styrenes, and conjugated polyalkenes; c) di-aromatic hydrocarbons (DAHs), which include naphthalenes, biphenyls, indenes, fluorenes, acenaphthenes, benzothiophenes, and dibenzothiophenes; and d) tri- and higher aromatic hydrocarbons (T+AHs), represented by phenanthrenes, pyrenes, fluoranthenes, chrysenes, triphenylenes, and benzanthracenes.
Principle
A known mass of a sample is injected into a high-performance liquid chromatograph equipped with a polar column, which shows minimal affinity for non-aromatic hydrocarbons while strongly selecting for aromatic hydrocarbons This selectivity allows for the separation of aromatic hydrocarbons from non-aromatic ones into distinct bands based on their ring structures, including mono-aromatic hydrocarbons (MAH), di-aromatic hydrocarbons (DAH), and tri-plus aromatic hydrocarbons (T+AH).
The column is linked to a refractive index detector that identifies components as they elute A data processor continuously monitors the electronic signals from the detector By comparing the signal amplitudes of aromatics in the sample with calibration standards, the mass fractions of MAHs, DAHs, and T+AHs are calculated The combined mass fractions of DAHs and T+AHs are reported as POLY-AH, while the total mass fraction of aromatic hydrocarbons includes MAHs, DAHs, and T+AHs.
Reagents and materials
WARNING — Protective gloves should be worn when handling aromatic compounds
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
Caution: This procedure may involve hazardous materials, operations, and equipment This Standard does not cover all safety issues related to its use Users are responsible for implementing necessary safety measures to protect personnel and comply with relevant statutory and regulatory requirements before applying the standard.
This procedure outlines a testing method to measure the levels of mono-aromatic, di-aromatic, and tri-aromatic hydrocarbons in diesel fuels that may include fatty acid methyl esters.
The content of polycyclic aromatic hydrocarbons (PAHs) is determined by adding the amounts of di-aromatic and tri-aromatic hydrocarbons Additionally, the total aromatic compounds are calculated by summing the individual types of aromatic hydrocarbons.
The standard HPLC techniques typically involve a dilution step; however, the method outlined in EN 12916 has been modified for paraffinic diesel fuels, including those blended with up to 7% (V/V) FAME, to accurately measure very low levels of aromatic components without requiring a dilution step.
Aromatic hydrocarbon types are classified based on their elution characteristics from a specific liquid chromatography column in relation to model aromatic compounds Their quantification relies on external calibration using a single aromatic compound, which may not accurately represent the aromatics in the sample Additionally, alternative techniques and methods may offer different classifications and quantifications of individual aromatic hydrocarbon types.
This method has been evaluated through the CEN/TC 19 ILS project, which was funded by the European Commission For more information, please contact the CEN/TC 19 Secretariat.
For the purposes of this annex, the following terms and definitions apply
C.3.1 non-aromatic hydrocarbon compound having a shorter retention time on the specified polar column than the majority of mono- aromatic hydrocarbons
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
Di-aromatic hydrocarbons (DAH) exhibit longer retention times on specified polar columns compared to most mono-aromatic hydrocarbons, yet they have shorter retention times than the majority of tri-aromatic hydrocarbons.
C.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
C.3.5 polycyclic aromatic hydrocarbon POLY-AH sum of the di-aromatic hydrocarbons and tri+-aromatic hydrocarbons
C.3.6 total aromatic hydrocarbon sum of the mono-aromatic hydrocarbons, di-aromatic hydrocarbons and tri+-aromatic hydrocarbons
Published and unpublished data reveal that the primary components of various hydrocarbon types include: a) non-aromatic hydrocarbons, which consist of acyclic and cyclic alkanes (paraffins and naphthenes) and potentially mono-alkenes; b) mono-aromatic hydrocarbons (MAHs), characterized by compounds such as benzenes, tetralins, indanes, higher naphthenobenzenes (like octahydrophenanthrenes), thiophenes, styrenes, and conjugated polyalkenes; c) di-aromatic hydrocarbons (DAHs), which include naphthalenes, biphenyls, indenes, fluorenes, acenaphthenes, benzothiophenes, and dibenzothiophenes; and d) tri- and higher aromatic hydrocarbons (T+AHs), represented by phenanthrenes, pyrenes, fluoranthenes, chrysenes, triphenylenes, and benzanthracenes.
A known mass of sample is injected into a high-performance liquid chromatograph equipped with a polar column, which shows minimal affinity for non-aromatic hydrocarbons but strong selectivity for aromatic hydrocarbons This selectivity allows for the effective separation of aromatic hydrocarbons from non-aromatic ones, organizing them into distinct bands based on their ring structures, including mono-aromatic hydrocarbons (MAH), di-aromatic hydrocarbons (DAH), and tri- or higher aromatic hydrocarbons (T+AH).
The column is linked to a refractive index detector that identifies components as they elute A data processor continuously monitors the electronic signals from the detector By comparing the amplitudes of signals from the sample's aromatics with calibration standards, the mass fractions of MAHs, DAHs, and T+AHs are calculated The combined mass fractions of DAHs and T+AHs are reported as POLY-AH, while the total mass fraction of aromatic hydrocarbons includes MAHs, DAHs, and T+AHs.
WARNING — Protective gloves should be worn when handling aromatic compounds
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
NOTE Cyclohexane might contain benzene as an impurity
C.5.2 Heptane, HPLC analytical grade, as the mobile phase
Batch to batch variation of the solvent water content, viscosity, refractive index, and purity may cause unpredictable column behaviour Drying (for example, by standing over activated molecular sieve type
5A) and filtering the mobile phase may help reducing the effect of trace impurities present in the solvent
To ensure optimal performance, it is advisable to de-gas the mobile phase prior to use This can be effectively achieved through methods such as helium sparging, vacuum degassing, or ultrasonic agitation, either online or offline Neglecting to de-gas the mobile phase may result in the occurrence of negative peaks.
C.5.4 1,2-Dimethylbenzene (o-xylene), of 98 % (m/m) minimum purity
Apparatus
The liquid chromatograph is a high-performance instrument designed to pump the mobile phase at flow rates ranging from 0.5 ml/min to 1.5 ml/min, achieving a precision of better than 0.5% and a pulsation of less than 1% full scale deflection under the specified test conditions.
2 injection device 5 refractive index detector
Figure C.1 — Diagrammatic representation of liquid chromatograph
C.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 calibration and sample solutions are injected into the chromatograph, ensuring repeatability through both manual and automatic sample injection systems For optimal results, it is advised to use a partial filling mode with an injection volume of less than half the total loop volume, while complete filling should involve overfilling the loop at least six times To verify the repeatability of the injection system, compare peak areas from a minimum of four injections of the calibration standard.
Injection volumes for samples and calibration can vary from the standard 10 μl, typically ranging between 3 μl and 20 μl, as long as they satisfy the criteria for injection repeatability, refractive index sensitivity, linearity, and column resolution.
C.6.3 Sample filter, if required (see C.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 PTFE filters have been found to be suitable
C.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 C.8.9, C.8.10 and C.8.12
Columns measuring between 150 mm and 300 mm in length, with internal diameters ranging from 4 mm to 5 mm, have proven to be effective To enhance the longevity and performance of the analytical column, it is advisable to utilize a guard column, such as one that is 30 mm long with a 4.6 mm internal diameter packed with amino-silica, and to replace it regularly.
Batch-to-batch variations in resolution and aromatic hydrocarbon selectivity have been observed in some commercial stationary phases, prompting laboratories to test individual columns before purchase to ensure they meet the required standards New columns are usually shipped in a solvent different from the mobile phase specified in the standard and should be conditioned by purging with heptane It is recommended to condition the column for at least two hours at a flow rate of 1 ml/min, although longer conditioning periods of up to two days may be necessary Alternatively, a reduced flow rate of 0.25 ml/min for a minimum of 12 hours, such as overnight, can also be effective.
Most laboratory columns demonstrate long-term stability, often lasting two years or more However, minor performance changes can go unnoticed without proper quality control To effectively monitor column and system performance, laboratories should regularly record column head pressure and calibrant retention times It is also highly recommended to engage in inter-laboratory precision monitoring schemes and to consistently use validated or internal reference gas oils during test procedures and column evaluations.
Used columns that do not meet standard requirements can be regenerated by flushing them in backflush mode with a polar solvent, such as dichloromethane, at a rate of 1 ml/min for two hours, followed by re-conditioning as if they were new Before discarding a used column, it is essential to thoroughly inspect all other system components for leaks, dead volumes, and potential blockages in filters, column frits, tubing, injector needles/seals, and valve rotors, as these issues may also affect column performance.
Temperature control is essential and can be achieved through various methods, including a heating block, an air-circulating HPLC column oven, or other temperature-controlled environments These systems must maintain a stable temperature within the range of 20 °C ± 1 °C to 40 °C ± 1 °C.
NOTE Cyclohexane might contain benzene as an impurity
C.5.2 Heptane, HPLC analytical grade, as the mobile phase
Batch to batch variation of the solvent water content, viscosity, refractive index, and purity may cause unpredictable column behaviour Drying (for example, by standing over activated molecular sieve type
5A) and filtering the mobile phase may help reducing the effect of trace impurities present in the solvent
To ensure optimal performance, it is advisable to de-gas the mobile phase prior to use This can be effectively achieved through methods such as helium sparging, vacuum degassing, or ultrasonic agitation, either online or offline Neglecting to de-gas the mobile phase may result in the occurrence of negative peaks.
C.5.4 1,2-Dimethylbenzene (o-xylene), of 98 % (m/m) minimum purity
The liquid chromatograph is a high-performance instrument designed to pump the mobile phase at flow rates ranging from 0.5 ml/min to 1.5 ml/min It offers precision better than 0.5% and maintains pulsation levels below 1% full scale deflection, as specified in the test conditions outlined in section C.8.
2 injection device 5 refractive index detector
Figure C.1 — Diagrammatic representation of liquid chromatograph
C.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 calibration and sample solutions are injected into the chromatograph, ensuring repeatability through both manual and automatic sample injection systems For optimal results, when using partial filling, the injection volume should be less than half the total loop volume, while complete filling is best achieved by overfilling the loop at least six times To verify the repeatability of the injection system, it is essential to compare peak areas from a minimum of four injections of the calibration standard.
Injection volumes for samples and calibration can vary from the standard 10 μl, typically ranging between 3 μl and 20 μl, as long as they satisfy the criteria for injection repeatability, refractive index sensitivity, linearity, and column resolution.
C.6.3 Sample filter, if required (see C.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 PTFE filters have been found to be suitable
C.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 C.8.9, C.8.10 and C.8.12
Analytical columns ranging from 150 mm to 300 mm in length and with an internal diameter of 4 mm to 5 mm have proven to be effective To enhance performance and longevity, it is advisable to use a guard column, such as a 30 mm by 4.6 mm ID packed with amino-silica, and to replace it regularly.
Batch-to-batch variations in resolution and aromatic hydrocarbon selectivity have been observed in some commercial stationary phases It is recommended that laboratories test individual columns before purchase to ensure they meet the required standards for resolution and selectivity New columns are usually shipped in a solvent different from the mobile phase specified in the standard and should be conditioned by purging with heptane A conditioning period of at least two hours at a flow rate of 1 ml/min is advised, although longer conditioning times of up to two days may be necessary Alternatively, a reduced flow rate of 0.25 ml/min for a minimum of 12 hours, such as overnight, can also be effective.
Most laboratory columns demonstrate long-term stability, often lasting two years or more However, minor performance changes can go unnoticed without proper quality control To effectively monitor column and system performance, laboratories should regularly record column head pressure and calibrant retention times It is also highly recommended to engage in inter-laboratory precision monitoring schemes and to consistently use validated or internal reference gas oils during testing and column evaluation.
Sample handling and storage
Sample handling storage shall be in line with EN ISO 3170 and the following additional instructions because some samples may contain FAME:
Samples must be stored at a temperature of 19 °C ± 5 °C If samples have been exposed to temperatures exceeding 25 °C for an extended period during storage or custody, this exposure must be reported.
— At least 24 h before a test, the blend shall be placed at ambient temperature
— When a portion of 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.
Apparatus preparation
C.8.1 Ensure that the equipment and any distribution system of sample is clean and dry before use
Make sure that the equipment for handling or testing the sample is not sensitive to FAME
Polytetrafluoro-ethylene, Viton® and Nylon are materials that should be used
Set up the liquid chromatograph, sample injection system, column, refractive index detector, and computing integrator according to the manufacturer's manuals (refer to Figure C.1) If utilizing a column oven, install the HPLC column within it Ensure that the sample injection system is maintained at the same temperature as the sample solution, typically at room temperature.
Regular maintenance of liquid chromatographs and their components is crucial for maintaining consistent performance Issues such as leakages and partial blockages in filters, frits, injector needles, and valve rotors can lead to inconsistencies in flow rates and poor injector repeatability.
To achieve optimal results, set the mobile phase flow rate to a constant between 0.8 ml/min and 1.2 ml/min, and ensure that the reference cell of the refractive index detector is completely filled with the mobile phase.
To minimize instrument drift, it is essential to fill the reference cell of the detector with mobile phase This can be achieved by either flushing the reference cell with mobile phase just before analysis and isolating it to prevent evaporation, or by maintaining a steady flow of mobile phase to compensate for evaporation Optimizing the flow is crucial to reduce cell mismatch caused by drying, temperature, or pressure gradients in the reference or analysis cells For certain detectors, maintaining a mobile phase flow in the reference cell at one-tenth of that in the analysis cell can effectively minimize these issues.
C.8.5 Allow the temperature of the column and of the refractive index detector, if it is equipped with temperature control, to stabilize
To prepare a system calibration standard 1 (SCS1), accurately weigh the following components: 1.0 g ± 0.1 g of cyclohexane, 0.1 g ± 0.01 g of 1-phenyldodecane, 0.5 g ± 0.05 g of 1,2-dimethylbenzene, 0.1 g ± 0.01 g of hexamethylbenzene, 0.1 g ± 0.01 g of naphthalene, 0.05 g ± 0.005 g of dibenzothiophene, and 0.05 g ± 0.005 g of 9-methylanthracene into a 100 ml volumetric flask Place the flask in an ultrasonic bath until all components are visibly dissolved in the 1,2-dimethylbenzene/cyclohexane mixture, then remove it and fill 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)
To prepare a system calibration standard 2 (SCS2), accurately weigh 0.4 g ± 0.1 g of FAME and 0.04 g ± 0.01 g of chrysene, then transfer them into a 100 ml volumetric flask Fill the flask to the mark with heptane and place the solution in an ultrasonic bath set 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 dark place (for example in a refrigerator)
When operating conditions are stable, indicated by a consistent horizontal baseline, inject 10 μl of the SCS1 solution It is crucial to ensure that the baseline drift during the HPLC analysis remains below 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
To achieve optimal results in the SCS1 analysis, it is crucial to elute the components in the following order: cyclohexane, phenyldodecane, 1,2 dimethylbenzene, hexamethylbenzene, naphthalene, dibenzothiophene, and 9-methylanthracene Additionally, it is essential to ensure baseline separation between all components for accurate identification and analysis.
The refractive index detector (C.6.6) is highly responsive to both abrupt and gradual temperature fluctuations in the eluent To ensure accurate measurements, it is crucial to maintain stable temperature conditions across the liquid chromatograph system Additionally, optimizing the temperature based on the stationary phase is essential for optimal performance.
C.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 range 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
The computer or computing integrator must be compatible with the refractive index detector, featuring a minimum sampling rate of 1 Hz It should enable peak area and retention time measurements, along with essential post-analysis data processing capabilities like baseline correction and re-integration While automatic peak detection, identification, and the calculation of sample concentrations from peak area measurements are recommended, they are not mandatory.
C.6.8 Volumetric flasks, 10 ml and 100 ml capacity, conforming to grade A of EN ISO 1042
C.6.9 Analytical balance, capable of weighing to the nearest 0,000 1 g
Sample handling storage shall be in line with EN ISO 3170 and the following additional instructions because some samples may contain FAME:
Samples must be stored at a temperature of 19 °C ± 5 °C If samples have been exposed to temperatures exceeding 25 °C for an extended period during storage or custody, this exposure must be reported.
— At least 24 h before a test, the blend shall be placed at ambient temperature
— When a portion of 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
C.8.1 Ensure that the equipment and any distribution system of sample is clean and dry before use
Make sure that the equipment for handling or testing the sample is not sensitive to FAME
Polytetrafluoro-ethylene, Viton® and Nylon are materials that should be used
Set up the liquid chromatograph, sample injection system, column, refractive index detector, and computing integrator according to the manufacturer's manuals (refer to Figure C.1) If utilizing a column oven, install the HPLC column within it Ensure that the sample injection system is maintained at the same temperature as the sample solution, typically at room temperature.
Regular maintenance of liquid chromatographs and their components is crucial for maintaining consistent performance Issues such as leakages and partial blockages in filters, frits, injector needles, and valve rotors can lead to inconsistencies in flow rates and poor injector repeatability.
To achieve optimal results, set the mobile phase flow rate to a constant between 0.8 ml/min and 1.2 ml/min, and ensure that the reference cell of the refractive index detector is completely filled with the mobile phase.
To minimize instrument drift, it is essential to fill the reference cell of the detector with mobile phase This can be achieved by either flushing the reference cell with mobile phase just before analysis and isolating it to prevent evaporation, or by maintaining a steady flow of mobile phase to compensate for evaporation Optimizing the flow is crucial to reduce cell mismatch caused by drying, temperature, or pressure gradients in the reference or analysis cells For certain detectors, maintaining a mobile phase flow through the reference cell at one-tenth of that through the analysis cell can effectively minimize these issues.
C.8.5 Allow the temperature of the column and of the refractive index detector, if it is equipped with temperature control, to stabilize
Calibration
C.9.1 Prepare four calibration standards referenced A, B, C and D at the approximate (but accurately known) concentrations given in Table C.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 (C.5.2)
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 C.1 — Concentrations of calibration standard components
Calibration standard 1,2 Dimethylbenzene g/100 ml Fluorene g/100 ml Phenanthrene g/100 ml
C.9.2 When operating conditions are steady (see C.8.8), inject 10 μl of calibration standard A Record the chromatogram and measure the peak areas for each aromatic standard (see Figure C.3)
Figure C.3— Chromatogram of calibration standard A
Repeat the procedure outlined in C.9.2 for calibration standards B, C, and D If the phenanthrene peak area in calibration standard D is too small for accurate measurement, create a new calibration standard, D +, with an increased phenanthrene concentration, such as 0.02 g/100 ml, and perform C.9.2 again.
To create calibration plots for aromatic standards such as 1,2 dimethylbenzene, fluorene, and phenanthrene, plot the concentration in g/100 ml against area counts Ensure that the resulting plots exhibit a linear relationship with a correlation coefficient exceeding 0.999 and an intercept within ± 0.01 g/100 ml.
A computer or data system may be used to perform these calibrations
Figure C.2— Chromatogram of the system calibration standard SCS1
C.8.11 Measure the retention times of the cyclohexane, phenyldodecane, 1,2 dimethylbenzene, hexamethylbenzene, dibenzothiophene and 9-methylanthracene peaks using the data system
C.8.12 Ensure that the resolution between cyclohexane and 1,2 dimethylbenzene is between 5,7 and 10
C.8.13 Calculate the cut times using the formulae given in C.11.3
C.8.14 Ensure the appearance of SCS 2 is homogeneous (C.8.7) 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
To ensure optimal performance of the column, it is essential to test it with the SCS2 method when initiating a new column, after a period of inactivity, or prior to running samples containing FAME.
C.9.1 Prepare four calibration standards referenced A, B, C and D at the approximate (but accurately known) concentrations given in Table C.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 (C.5.2)
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 C.1 — Concentrations of calibration standard components
Calibration standard 1,2 Dimethylbenzene g/100 ml Fluorene g/100 ml Phenanthrene g/100 ml
C.9.2 When operating conditions are steady (see C.8.8), inject 10 μl of calibration standard A Record the chromatogram and measure the peak areas for each aromatic standard (see Figure C.3)
Figure C.3— Chromatogram of calibration standard A
Repeat the calibration process outlined in C.9.2 for calibration standards B, C, and D If the phenanthrene peak area in calibration standard D is too small for accurate measurement, create a new calibration standard, D +, with an increased phenanthrene concentration, such as 0.02 g/100 ml, and conduct the calibration again as per C.9.2.
To create calibration plots for aromatic standards such as 1,2 dimethylbenzene, fluorene, and phenanthrene, plot the concentration in g/100 ml against area counts Ensure that the resulting plots are linear, with a correlation coefficient exceeding 0.999 and an intercept within ± 0.01 g/100 ml.
A computer or data system may be used to perform these calibrations.