⚗️ Aromatic hydrocarbon content in diesel fuel
In short
Determination of mono-aromatic, di-aromatic and tri+-aromatic hydrocarbons in diesel fuel, paraffinic diesel fuel and petroleum distillates by high performance liquid chromatography with a polar column and a refractive index detector. The test is performed according to PN-EN 12916:2024-08; Types determined: MAH, DAH, T+AH; POLY-AH = DAH + T+AH; total aromatics = MAH + DAH + T+AH; result in % (m/m). The procedure comprises 6 steps; it is used for: Diesel fuel with FAME up to 30 % (V/V) and petroleum distillates boiling from 150 °C to 400 °C — Procedure A, Paraffinic diesel fuel with FAME up to 7 % (V/V) — Procedure B, Checking the compliance of diesel fuel with the requirement of at most 8.0 % (m/m) polycyclic aromatic hydrocarbons (Journal of Laws 2024 item 1018).
At a glance
- Standard: PN-EN 12916:2024-08
- Category: Petrochemistry
- Procedure steps: 6
- Types determined: MAH, DAH, T+AH; POLY-AH = DAH + T+AH; total aromatics = MAH + DAH + T+AH; result in % (m/m)
- Procedure A: diesel fuel with FAME up to 30 % (V/V), distillates boiling from 150 °C to 400 °C; dilution with heptane
- Procedure B: paraffinic diesel fuel with FAME up to 7 % (V/V); no dilution; storage of samples at (19 ± 5) °C
Overview
STATUS (as of 06.11.2026). According to the PKN catalogue card (read on 06.11.2026) PN-EN 12916:2024-08 is an English version published on 16.08.2024 (25 pages), implementing EN 12916:2024 [IDT] and replacing PN-EN 12916+A1:2023-01 (English version), with no withdrawal note; there is no Polish version in the catalogue. EN 12916:2024 superseded EN 12916:2019+A1:2022. According to the foreword, the main change is the new Annex C (determination of tri+-aromatics and additional sampling requirements), improved guidance for paraffinic diesel fuel in Annex B with example chromatograms, storage requirements for samples restricted to paraffinic diesel fuel and the addition of calibration with a reference material; a study from 2021 confirmed the precision for polycyclic aromatic hydrocarbons and di-aromatics in the range (6–10) % (m/m). The description is based on the preview of SIST EN 12916:2024 (text of EN 12916:2024: foreword, Clauses 1–7); we did not have Clauses 8–12.
SCOPE. The standard specifies two procedures. Procedure A applies to diesel fuel which may contain up to 30 % (V/V) fatty acid methyl esters (FAME) and to petroleum distillates boiling in the range from 150 °C to 400 °C; the sample is diluted with heptane. Procedure B applies to paraffinic diesel fuel with at most 7 % (V/V) FAME; the sample is injected undiluted in order to determine low aromatic contents. Compounds containing sulfur, nitrogen and oxygen as well as conjugated di-alkenes and poly-alkenes can interfere; mono-alkenes do not interfere. The measurement ranges are given in Tables 2 and 3 of the standard.
HYDROCARBON TYPES. The aromatic types are defined by convention by their elution time from the specified polar column relative to model compounds and are quantified by external calibration with one compound for each type. According to the standard the major constituents are: mono-aromatics — benzenes, tetralins, indanes, higher naphthenobenzenes, thiophenes, styrenes and conjugated poly-alkenes; di-aromatics — naphthalenes, biphenyls, indenes, fluorenes, acenaphthenes, benzothiophenes and dibenzothiophenes; tri+-aromatics — phenanthrenes, pyrenes, fluoranthenes, chrysenes, triphenylenes and benzanthracenes. Polycyclic aromatic hydrocarbons (POLY-AH) are the sum of di- and tri+-aromatics — not only compounds with three or more rings. Other techniques may classify aromatics differently.
REGULATIONS. The regulation on quality requirements for liquid fuels (Journal of Laws 2024 item 1018, Annex 3 item 4) allows at most 8.0 % (m/m) of polycyclic aromatic hydrocarbons in diesel fuel, and the regulation on test methods for liquid fuels (Journal of Laws 2024 item 1058, Part II point 4) specifies for their determination the HPLC method with a refractive index detector according to the standard implementing EN 12916 and defines the result as the sum of DAH and T+AH. A similar method is described in ASTM D6591 (diesel fuels and distillates boiling from 150 °C to 400 °C); we do not assess the equivalence of the two documents here.
WHAT WE DO NOT GIVE HERE. We did not have Clauses 8–12 of the standard: we do not give the calibration procedure (which compounds of Clause 5 are used for calibration and which for checking resolution), solution concentrations, flow rate and temperature, resolution criteria, formulae, the ranges of Tables 2 and 3 or the precision. We have removed figures without a source ("typical" content ranges, repeatability, column dimensions, step times), brands and prices of apparatus, names of control institutions and statements about the effect of aromatics on engines and emissions.
Method principle
A weighed sample (diluted with heptane in Procedure A, undiluted in Procedure B) is injected in a fixed volume into a high performance liquid chromatograph with a polar column. The column has little affinity for non-aromatic hydrocarbons and strong selectivity for aromatic ones, which it separates from the non-aromatics and into bands according to ring structure: mono-aromatics (MAH), di-aromatics (DAH) and tri+-aromatics (T+AH). The components are detected by a refractive index detector, and the signal amplitudes of the aromatics in the sample are compared with those of calibration standards to calculate the mass fractions of MAH, DAH and T+AH. The sum of DAH and T+AH is the polycyclic aromatic hydrocarbon content (POLY-AH), and the sum of all three types is total aromatics. In Procedure A the column may be backflushed after the aromatics have eluted to remove remaining components, e.g. FAME.
Applications
- Diesel fuel with FAME up to 30 % (V/V) and petroleum distillates boiling from 150 °C to 400 °C — Procedure A
- Paraffinic diesel fuel with FAME up to 7 % (V/V) — Procedure B
- Checking the compliance of diesel fuel with the requirement of at most 8.0 % (m/m) polycyclic aromatic hydrocarbons (Journal of Laws 2024 item 1018)
- Determination of total aromatics as the sum of MAH, DAH and T+AH
Key parameters
| Parameter | Value |
|---|---|
| Types determined | MAH, DAH, T+AH; POLY-AH = DAH + T+AH; total aromatics = MAH + DAH + T+AH; result in % (m/m) |
| Procedure A | diesel fuel with FAME up to 30 % (V/V), distillates boiling from 150 °C to 400 °C; dilution with heptane |
| Procedure B | paraffinic diesel fuel with FAME up to 7 % (V/V); no dilution; storage of samples at (19 ± 5) °C |
| Mobile phase | HPLC grade heptane; flow rate the pump must provide: 0.5 ml/min to 1.5 ml/min |
| Column | stainless steel, 3, 5 or 10 µm packing: amino-bonded or amino/cyano-bonded silica |
| Injection | nominally 10 µl (typically 3 µl to 20 µl permitted), repeatability better than 1 % |
| Requirement for diesel fuel (Journal of Laws 2024 item 1018) | at most 8.0 % (m/m) polycyclic aromatic hydrocarbons |
Standard
- Standard number
- PN-EN 12916:2024-08
- Title (PL)
- Przetwory naftowe — Oznaczanie grup węglowodorów aromatycznych w średnich destylatach — Metoda wysokosprawnej chromatografii cieczowej z detektorem współczynnika załamania światła
- Title (EN)
- Petroleum products — Determination of aromatic hydrocarbon types in middle distillates — High performance liquid chromatography method with refractive index detection
Step-by-step procedure
-
Sampling and storage
Take the sample according to EN ISO 3170 or EN ISO 3171. Store paraffinic diesel fuel samples for Procedure B at (19 ± 5) °C (report longer exposure above 25 °C) and bring them to ambient temperature at least 24 h before the test.
-
Preparing the mobile phase and apparatus
Prepare the heptane (dried and filtered if necessary, degassed). Establish a constant temperature of the column, injector, solvent and detector.
-
Calibration and system check
Calibrate the system with standards (one compound for each aromatic type) and check the column resolution according to Clauses 8–9 of the standard; details are not given here.
-
Preparation of the sample
Procedure A: weigh the sample and dilute it with heptane in a volumetric flask. Procedure B: the sample is injected undiluted. If necessary, filter through a 0.45 µm filter.
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Analysis
Inject the same volume of sample solution as of the calibration solutions (nominally 10 µl). Record the bands of non-aromatics, MAH, DAH and T+AH; in Procedure A the column may be backflushed after the aromatics have eluted.
-
Calculation and result
Compare the aromatic signals of the sample with the standards and calculate the mass fractions of MAH, DAH and T+AH. Report POLY-AH as the sum of DAH and T+AH and total aromatics as the sum of the three types, in % (m/m).
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Liquid chromatograph | Mobile phase pump 0.5 ml/min to 1.5 ml/min with a precision better than 0.5 % and pulsation below 1 % of full scale; parts resistant to FAME (recommended: polytetrafluoroethylene, fluoroelastomer, nylon) | — |
| Sample injection system | Nominally 10 µl of solution, repeatability better than 1 % (checked with at least four injections of a standard); equal volumes of calibration and sample solutions | — |
| Column (column system) | Stainless steel HPLC column with amino-bonded or amino/cyano-bonded silica, particle size 3, 5 or 10 µm, meeting the resolution requirements of the standard (guidance in Annex A) | — |
| Refractive index detector | Refractive index range 1.3 to 1.6, linear response over the calibration range; preferably at the same temperature as the column | — |
| Temperature control | Column oven or a laboratory maintaining a constant temperature in the range (20 ± 1) °C to (40 ± 1) °C; the detector is sensitive to changes in eluent temperature | — |
| Computer or integrator | Sampling rate of at least 1 Hz, peak area and retention time measurement, baseline correction and re-integration | — |
| Volumetric flasks and balance | 10 ml and 100 ml grade A flasks (EN ISO 1042); analytical balance readable to 0.1 mg; if necessary a filter of porosity 0.45 µm or less | — |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| HPLC grade heptane | 142-82-5 | Mobile phase; batch-to-batch variation (water, viscosity, refractive index) affects column behaviour; drying (e.g. over 5A molecular sieve) and filtering help; degassing is recommended (failure to degas gives negative peaks) |
| Cyclohexane | 110-82-7 | Purity at least 99 % (m/m); can contain benzene as an impurity |
| 1,2-Dimethylbenzene (o-xylene) | 95-47-6 | Purity at least 98 % (m/m) |
| Naphthalene, fluorene, phenanthrene | 91-20-3 | Purity at least 98 % (m/m) each (CAS: naphthalene 91-20-3, fluorene 86-73-7, phenanthrene 85-01-8) |
| 1-Phenyldodecane and hexamethylbenzene | 123-01-3 | Purity at least 98 % (m/m) (CAS: 1-phenyldodecane 123-01-3, hexamethylbenzene 87-85-4) |
| Dibenzothiophene, 9-methylanthracene, chrysene | 132-65-0 | Purity at least 95 % (m/m) (CAS: dibenzothiophene 132-65-0, 9-methylanthracene 779-02-2, chrysene 218-01-9) |
| FAME and reference material | — | FAME complying with EN 14214; reference material — samples containing aromatics at concentrations comparable to the test sample |
Health and safety (OHS)
- The standard warns: aromatic compounds can be volatile and flammable, their vapours can form explosive mixtures with air, they can cause acute or chronic harm when inhaled or in contact with the skin, and they can pollute water
- Heptane (harmonised CLP classification): highly flammable (H225), may be fatal if swallowed and enters airways (H304), causes skin irritation (H315), may cause drowsiness or dizziness (H336), very toxic to aquatic life with long-lasting effects (H400, H410)
- Establishing safety practices and meeting statutory requirements before applying the standard is the responsibility of the user (warning in Clause 1 of the standard)
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 12916:2024-08 — “Petroleum products — Determination of aromatic hydrocarbon types in middle distillates — High performance liquid chromatography method with refractive index detection”.
How does this method work?
A weighed sample (diluted with heptane in Procedure A, undiluted in Procedure B) is injected in a fixed volume into a high performance liquid chromatograph with a polar column. The column has little affinity for non-aromatic hydrocarbons and strong selectivity for aromatic ones, which it separates from the non-aromatics and into bands according to ring structure: mono-aromatics (MAH), di-aromatics (DAH) and tri+-aromatics (T+AH).
What is the measuring range and accuracy?
Types determined: MAH, DAH, T+AH; POLY-AH = DAH + T+AH; total aromatics = MAH + DAH + T+AH; result in % (m/m); Procedure A: diesel fuel with FAME up to 30 % (V/V), distillates boiling from 150 °C to 400 °C; dilution with heptane; Procedure B: paraffinic diesel fuel with FAME up to 7 % (V/V); no dilution; storage of samples at (19 ± 5) °C; Mobile phase: HPLC grade heptane; flow rate the pump must provide: 0.5 ml/min to 1.5 ml/min.
How long does the test take?
The procedure comprises 6 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Liquid chromatograph, Sample injection system, Column (column system), Refractive index detector, Temperature control, Computer or integrator, Volumetric flasks and balance.
Where is this test used?
Diesel fuel with FAME up to 30 % (V/V) and petroleum distillates boiling from 150 °C to 400 °C — Procedure A; Paraffinic diesel fuel with FAME up to 7 % (V/V) — Procedure B; Checking the compliance of diesel fuel with the requirement of at most 8.0 % (m/m) polycyclic aromatic hydrocarbons (Journal of Laws 2024 item 1018); Determination of total aromatics as the sum of MAH, DAH and T+AH.
What safety precautions apply?
The standard warns: aromatic compounds can be volatile and flammable, their vapours can form explosive mixtures with air, they can cause acute or chronic harm when inhaled or in contact with the skin, and they can pollute water; Heptane (harmonised CLP classification): highly flammable (H225), may be fatal if swallowed and enters airways (H304), causes skin irritation (H315), may cause drowsiness or dizziness (H336), very toxic to aquatic life with long-lasting effects (H400, H410); Establishing safety practices and meeting statutory requirements before applying the standard is the responsibility of the user (warning in Clause 1 of the standard).
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN 12916.