🔥 Determination of the acid value of light-coloured fatty acid methyl esters (FAME) by titration — about 20 g of sample (± 0.001 g) is dissolved in 100 ml of neutralised mixture of ethanol and diethyl ether (1 + 1) and titrated with ethanolic KOH 0.1 mol/l against phenolphthalein to a colour persisting for at least 15 s; range 0.10–1.00 mg KOH/g, result to two decimal places, repeatability 0.02 and reproducibility 0.06 mg KOH/g, PN-EN 14104

Petrochemistry PN-EN 14104

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in the iTeh sample of SIST EN 14104:2021 (text of EN 14104:2021, English) — in full: from the title page through the contents, the European foreword and Clauses 1–12 (scope, references, definition, principle, reagents, apparatus, sampling, preparation, procedure, calculation, precision, test report). Outside the sample remain only the informative Annex A (results of an interlaboratory trial) and the bibliography.

ACCORDING TO THE TEXT OF EN 14104:2021 (Clauses 1–12). The standard was prepared by CEN/TC 307 “Oilseeds, vegetable and animal fats and oils and their by-products — Methods of sampling and analysis” (secretariat AFNOR); CEN approved it on 6.12.2020; it supersedes EN 14104:2003, and the changes compared with the previous edition according to the foreword are: Clause 5 “Reagents” revised, an automated titration system with optical detection added as an alternative, editorial revision. Scope (1): titrimetric method for the acid value of light-coloured FAME in the range 0.10–1.00 mg KOH/g; for oils and fats the acid value is specified in EN ISO 660 (note 2). Normative references (2): EN ISO 661 (preparation of test sample), EN ISO 3696. Definition (3.1): acid value — the number of milligrams of potassium hydroxide required to neutralise the free fatty acids in 1 g of FAME; if the sample contains mineral acids, these are determined as part of the total acid value — the method does not distinguish weak acidity (free fatty acids) from strong acidity (mineral acids). Principle (4): the test portion is dissolved in a suitable solvent mixture and titrated with a standardised KOH solution against phenolphthalein. Reagents (5): analytical grade, water of grade 3 according to EN ISO 3696; toluene, isopropanol, ethanol 95–97 % (solvent A), diethyl ether free of peroxides, stabilised with BHT (solvent B); solvent mixture — equal volumes of A and B, neutralised just before use with the KOH solution in the presence of 0.3 ml phenolphthalein per 100 ml; if diethyl ether cannot be used — toluene with ethanol or toluene with isopropanol (1 + 1), or isopropanol alone; for dark samples more mixture and indicator may be necessary; standards: potassium hydrogen phthalate (> 99.5 %, 2 h at 120 °C) or benzoic acid (> 99.5 %, carefully fused at about 130 °C); KOH 0.1 mol/l in ethanol (about 6.6 g per 1000 ml, used after at least 5 days, decanted into a brown glass bottle, colourless or straw yellow, protected from CO2, e.g. by a soda lime tube) — aqueous KOH or NaOH solutions are allowed if water does not cause phase separation, and isopropanol instead of ethanol; standardisation on about 180 mg potassium hydrogen phthalate or about 100 mg benzoic acid in 100 ml water against phenolphthalein (formulae with molar masses 204.23 and 122.12); phenolphthalein 10 g/l in ethanol. Apparatus (6): 10 ml burette graduated in 0.02 ml, class A according to EN ISO 385; balance accurate to ± 0.001 g or better. Sampling (7) is not part of the method (recommended: EN ISO 5555). Preparation (8): according to EN ISO 661; the sample shall not be heated or filtered. Procedure (9): about 20 g (± 0.001 g) in a 250 ml conical flask; dissolve in 100 ml of neutralised mixture, add a few drops of phenolphthalein and titrate with KOH while stirring to the point where a single drop produces a slight but definite colour change persisting for at least 15 s; an automated system with optical detection of the end point is allowed if validated to meet the precision of Clause 11; if the solution becomes turbid — add mixture until clear. Calculation (10): AV = 56.1 × V × c / m (V — volume of KOH in ml, c — concentration in mol/l, m — mass of test portion in g), result in mg KOH/g, rounded to the second decimal place. Precision (11): repeatability 0.02 mg KOH/g, reproducibility 0.06 mg KOH/g (exceeded at most once in 20 determinations); the values may not apply outside the concentration ranges and matrices of the trial. Test report (12): at least the reference to EN 14104:2021, the result, deviations, unusual features and date.

STATUS (as of 03.10.2026). In the PKN search (term “PN-EN 14104”, 03.10.2026) PN-EN 14104:2021-06 (English version, “Fat and oil derivatives — Fatty Acid Methyl Esters (FAME) — Determination of acid value”, “Introduces: EN 14104:2021 [IDT]”) has no withdrawal note, and PN-EN 14104:2004 (Polish version) has the description “Withdrawn and replaced by PN-EN 14104:2021-06 — English version”; the search also shows the unrelated PN-ISO 14104:2002 (gears, withdrawn). In the iTeh catalogue (read on 03.10.2026) EN 14104:2021 has the status “Published” (publication 13.01.2021). What changed for the result between the 2003 and 2021 editions the foreword states directly: revised reagents and optical detection added as an alternative; we did not read the text of the 2003 edition.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read on 03.10.2026). The number 14104 appears in 13 records at 8 laboratories: AB 009, AB 098, AB 103, AB 387, AB 391, AB 484, AB 1668, AB 1679. In the current PCA documents (read on 03.10.2026, issues from 19.09.2025 to 30.07.2026) the number appears in 13 rows of the same 8 laboratories (AB 387 — 4, AB 103 and AB 484 2 each, the others 1 each). The form “PN-EN 14104:2021-06” at five laboratories, without year (“PN-EN 14104”) at AB 009, AB 098 and AB 387 (at AB 009 and AB 387 in a flexible scope marked “E”). The “Laboratories” tab (“PN-EN 14104”) shows the same 8 laboratories — checked with the tab query on the production server labcoda.pl on 03.10.2026.

SUSPENSION (PCA document). AB 103 (issue No 42 of 18.02.2026) has two items “Acid value” according to PN-EN 14104:2021-06 for FAME and diesel fuel with FAME: the item with the range (0.10–0.65) mg KOH/g is marked “*)” — “Accreditation suspended at the request of the body in the part of the scope marked in bold italics from 18.02.2026 to 17.02.2027”; the other, (0.16–0.68) mg KOH/g, is not marked. The suspensions at AB 484 (from 30.07.2026 to 26.01.2027) concern items other than the acid value.

WHAT THE LABORATORIES TEST (items in PCA). Titrimetric method everywhere. FAME: AB 391 (0.10–0.50) mg KOH/g, AB 1679 (0.30–0.90), AB 009 and AB 1668 (0.10–1.00), AB 484 (0.10–1.00, also written “mg/g KOH”). FAME and diesel fuel with FAME: AB 103 (0.10–0.65 — suspended; 0.16–0.68), AB 484 (0.10–1.00). Liquid fuels without closer specification: AB 098 (together with ASTM D 3242) and AB 387 (4 items, without a range in the row). The standard concerns light-coloured FAME (1); diesel fuel with FAME lies outside its scope, and for oils and fats there is EN ISO 660 (at AB 103 in the adjacent item, (0.16–46.2) mg KOH/g).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the sample: heating or filtering the sample before the determination is prohibited (8). With the solvent: the mixture is neutralised just before use (5.5). With the titrant: a bottle connected to the burette is protected against intake of CO2 (e.g. with a soda lime tube), and the solution concentration is controlled by standardisation on phthalate or benzoic acid (5.8). With the end point: the colour must persist for at least 15 s (9.2.1); a turbid solution — add mixture (9.2.2). With interpretation: mineral acids are included in the result, the method does not distinguish them (3.1, note 2). With the range: below 0.10 and above 1.00 mg KOH/g the method is outside its scope (1), and the precision may not apply outside the matrices of the trial (11.1) — this also concerns diesel fuel with FAME.

WHAT WE DO NOT GIVE. We did not read Annex A, so we do not give the number of laboratories and samples of the interlaboratory trial. Nor do we give requirements of fuel specifications (e.g. the maximum acid value of FAME) — we did not read the texts of product standards for this entry.

Method principle

About 20 g of FAME is dissolved in 100 ml of a neutralised mixture of equal volumes of ethanol and diethyl ether (or toluene with ethanol or isopropanol) and titrated with a standardised ethanolic KOH 0.1 mol/l solution against phenolphthalein to a slight, definite colour persisting for at least 15 s (a validated titrator with optical detection may be used). Acid value AV = 56.1 × V × c / m, in mg KOH/g, to two decimal places.

Applications

• Light-coloured fatty acid methyl esters (FAME, biodiesel) — acid value 0.10–1.00 mg KOH/g (1)
• Mineral acids are included in the result — the method does not distinguish weak from strong acidity (3.1)
• FAME, diesel fuel with FAME and liquid fuels — titrimetric method in the accreditation scopes of 8 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 14104:2021-06

Title (PL)

Produkty przetwarzania olejów i tłuszczów — Estry metylowe kwasów tłuszczowych (FAME) — Oznaczanie liczby kwasowej

Title (EN)

Fat and oil derivatives — Fatty Acid Methyl Esters (FAME) — Determination of acid value

Step-by-step procedure

1. Sample

   Preparation according to EN ISO 661; do not heat or filter. PN-EN 14104:2021-06 current (PKN search, 03.10.2026).

2. Test portion

   About 20 g (± 0.001 g) into a 250 ml conical flask.

3. Dissolution

   100 ml of mixture neutralised just before use; a few drops of phenolphthalein.

4. Titration

   KOH 0.1 mol/l, while stirring, to a colour persisting for at least 15 s; if turbid, add mixture.

5. Result

   AV = 56.1 × V × c / m [mg KOH/g], rounded to the second decimal place.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Diethyl ether, ethanol, isopropanol and toluene are flammable; the ether must be free of peroxides (5.4)
• Potassium hydroxide solutions are corrosive
• The standard warns that its use may involve hazardous materials and operations, and that safety measures are the responsibility of the user (1)

Frequently asked questions