⛽ FAME content in diesel fuel
In short
Determination of fatty acid methyl ester (FAME/biodiesel) content in diesel fuel by infrared spectrometry at 1745 cm⁻¹. The test is performed according to PN-EN 14078:2014; Range A: 0.05–3% V/V FAME (cell ~0.5 mm). The procedure comprises 10 steps (about 1 h 17 min in total); it is used for: Diesel fuel B7 quality control (PN-EN 590) — limit ≤7.0% V/V FAME, Testing of B10, B20 and B100 fuels (PN-EN 14214), Verification of National Indicative Target (NIT) for biocomponents.
At a glance
- Standard: PN-EN 14078:2014
- Category: Petrochemistry
- Procedure steps: 10
- Total time of stages: 1 h 17 min
- Range A: 0.05–3% V/V FAME (cell ~0.5 mm)
- Range B: 3–20% V/V FAME (cell ~0.1 mm)
- Range C: 20–50% V/V FAME (cell 0.05–0.1 mm with dilution)
Overview
Fatty Acid Methyl Esters (FAME) constitute a biocomponent added to diesel fuel to reduce CO₂ emissions and fulfill the fuel obligation resulting from Directive 2009/28/EC (RED) and Polish biocomponent law. Standard B7 diesel fuel contains up to 7% V/V FAME, while B10, B20 and B100 fuels — correspondingly higher concentrations.
Precise determination of FAME content is crucial for several reasons: exceeding the 7% limit in standard diesel causes non-compliance with PN-EN 590 standard, too high FAME content lowers fuel oxidation stability, increases risk of microorganism growth and may cause low temperature problems (CFPP). Conversely, too low FAME addition means failure to meet the National Indicative Target (NIT).
The infrared (IR) spectrometry method utilizes the fact that FAME molecules possess an ester C=O bond which absorbs IR radiation at 1745 cm⁻¹. Pure mineral diesel fuel does not have this absorption, so measurement of band intensity at 1745 cm⁻¹ allows direct determination of FAME content. The sample is diluted with hexane and transmission is measured in a liquid cell of appropriate layer thickness.
The standard defines three measurement ranges: A (0.05–3% V/V), B (3–20% V/V), C (20–50% V/V), each requiring different cell thickness and appropriate dilution.
Method principle
A diesel fuel sample is diluted with n-hexane and placed in a liquid cell with KBr, NaCl or CaF₂ windows. The transmittance or absorbance of IR radiation in the carbonyl C=O band range at 1745 cm⁻¹ is measured. The absorbance peak height is proportional to FAME concentration in the sample. The result is read from a calibration curve prepared based on certified FAME/diesel standard solutions of known concentrations. For higher concentration ranges, thinner cells or greater dilution are used.
Applications
- Diesel fuel B7 quality control (PN-EN 590) — limit ≤7.0% V/V FAME
- Testing of B10, B20 and B100 fuels (PN-EN 14214)
- Verification of National Indicative Target (NIT) for biocomponents
- Control at fuel depots — checking blending proportions
- Fuel station monitoring — compliance with dispenser declaration
- Proficiency testing and interlaboratory comparisons (PT)
- Customs control of imported fuels
Key parameters
| Parameter | Value |
|---|---|
| Range A | 0.05–3% V/V FAME (cell ~0.5 mm) |
| Range B | 3–20% V/V FAME (cell ~0.1 mm) |
| Range C | 20–50% V/V FAME (cell 0.05–0.1 mm with dilution) |
| Measurement wavenumber | 1745 cm⁻¹ (ester C=O band) |
| Repeatability (range A) | 0.12% V/V (at 3% FAME) |
| PN-EN 590 limit (B7) | ≤7.0% V/V |
Standard
- Standard number
- PN-EN 14078:2014
- Title (PL)
- Ciekłe przetwory naftowe — Oznaczanie zawartości estrów metylowych kwasów tłuszczowych (FAME) w średnich destylatach — Metoda spektrometrii w podczerwieni
- Title (EN)
- Liquid petroleum products — Determination of fatty acid methyl ester (FAME) content in middle distillates — Infrared spectrometry method
Step-by-step procedure
-
FTIR spectrometer calibration
Verify apparatus wavelength calibration. Perform background test with empty cell or cell with pure hexane.
-
Calibration curve preparation
Prepare series of FAME/diesel standards of known concentrations (e.g., 0.5%, 1%, 2%, 3%, 5%, 7%). Dilute with hexane in appropriate proportions.
-
Standard measurement
Measure absorbance of each standard at 1745 cm⁻¹. Prepare calibration curve (absorbance vs. FAME concentration). Check linearity (R² ≥ 0.999).
-
Sample preparation
Dilute diesel fuel sample with hexane in proportion depending on expected FAME concentration (e.g., 1:1 for range A).
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Cell filling
Fill liquid cell with diluted sample using syringe. Ensure no air bubbles in optical path.
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Sample measurement
Place cell in FTIR chamber. Perform scan (typically 16–32 scans, 4 cm⁻¹ resolution). Read absorbance at 1745 cm⁻¹.
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Result reading from curve
Based on measured absorbance, read FAME concentration from calibration curve. Account for dilution factor.
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Cell washing
Rinse cell with hexane (3×), then acetone. Dry with dry air or nitrogen stream.
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Quality control
Measure control sample (CRM) every 10 determinations. Check duplicate repeatability. Deviation from certified value ≤ acceptance limit.
-
Result recording
Record result as % V/V FAME to 0.1% accuracy. Compare with standard limit (e.g., ≤7.0% for B7).
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| FTIR spectrometer | PerkinElmer Spectrum Two, Shimadzu IRSpirit, Bruker Alpha II, Thermo Nicolet iS5 | 50 000–150 000 PLN |
| Liquid cells with IR windows | KBr/CaF₂ cells, thickness 0.05–0.5 mm, Specac Omni-Cell | 2 000–6 000 PLN/pc. |
| FAME/diesel calibration standards | CPAchem / Paragon Scientific set, certified concentrations | 3 000–8 000 PLN / set |
| Micropipettes and volumetric glassware | Eppendorf Research Plus, volumetric flasks 10–50 mL | 500–2 000 PLN |
| Air dryer / N₂ generator | Dryer for FTIR chamber, Parker Balston | 5 000–15 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| n-Hexane | 110-54-3 | Analytical grade or for IR spectroscopy, for sample dilution. Purity ≥95% |
| Reference FAME (RME/SME) | 67784-80-9 | Rapeseed or soy methyl ester, certified CRM for calibration |
| Reference diesel fuel (without FAME) | — | Certified "blank diesel" for calibration standard preparation |
| Acetone | 67-64-1 | For washing liquid cells between measurements |
| Silica gel with molecular balls | — | For drying hexane and maintaining low humidity |
Health and safety (OHS)
- N-hexane — highly flammable, neurotoxic with chronic exposure, work under fume hood
- Acetone — flammable and irritating, avoid vapor inhalation
- KBr/NaCl windows — hygroscopic, do not touch with bare fingers, protect from moisture
- IR radiation — low risk, but do not look directly at interferometer laser beam
- Nitrile gloves, safety glasses and coat mandatory
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 14078:2014 — “Liquid petroleum products — Determination of fatty acid methyl ester (FAME) content in middle distillates — Infrared spectrometry method”.
How does this method work?
A diesel fuel sample is diluted with n-hexane and placed in a liquid cell with KBr, NaCl or CaF₂ windows. The transmittance or absorbance of IR radiation in the carbonyl C=O band range at 1745 cm⁻¹ is measured.
What is the measuring range and accuracy?
Range A: 0.05–3% V/V FAME (cell ~0.5 mm); Range B: 3–20% V/V FAME (cell ~0.1 mm); Range C: 20–50% V/V FAME (cell 0.05–0.1 mm with dilution); Measurement wavenumber: 1745 cm⁻¹ (ester C=O band).
How long does the test take?
The times given for the individual stages add up to approximately 1 h 17 min. The procedure comprises 10 steps.
What equipment is required?
FTIR spectrometer, Liquid cells with IR windows, FAME/diesel calibration standards, Micropipettes and volumetric glassware, Air dryer / N₂ generator. Indicative cost of the core instrument (FTIR spectrometer): 50 000–150 000 PLN.
Where is this test used?
Diesel fuel B7 quality control (PN-EN 590) — limit ≤7.0% V/V FAME; Testing of B10, B20 and B100 fuels (PN-EN 14214); Verification of National Indicative Target (NIT) for biocomponents; Control at fuel depots — checking blending proportions; Fuel station monitoring — compliance with dispenser declaration; Proficiency testing and interlaboratory comparisons (PT); Customs control of imported fuels.
What safety precautions apply?
N-hexane — highly flammable, neurotoxic with chronic exposure, work under fume hood; Acetone — flammable and irritating, avoid vapor inhalation; KBr/NaCl windows — hygroscopic, do not touch with bare fingers, protect from moisture; IR radiation — low risk, but do not look directly at interferometer laser beam; Nitrile gloves, safety glasses and coat mandatory.
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 14078.