⛽ Determination of the iodine value of fatty acid methyl esters (FAME, biodiesel) by titration — a 0,13–0,15 g sample is dissolved in a mixture of cyclohexane and acetic acid, 25 ml of Wijs reagent is added, after 1 h in the dark potassium iodide and water are added and the liberated iodine is titrated with 0,1 mol/l sodium thiosulfate against a blank; result in g iodine/100 g, PN-EN 14111

Petrochemistry PN-EN 14111

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN 14111:2022-11 (English version), in full (here in the wording of EN 14111:2022, Clause 1; the card gives a Polish translation): “This document specifies a titrimetric method for the determination of iodine value in Fatty Acid Methyl Esters, hereinafter referred as FAME. The precision statement of this test method was determined in a Round Robin exercise with iodine values in the range 111 g iodine/100 g to 129 g iodine/100 g. The test method is also applicable for lower iodine values; however, the precision statement is not established for iodine values below 111 g iodine/100 g. WARNING — The use of this document can involve hazardous materials, operations and equipment. This document does not purport to address all of the safety problems associated with its use. It is the responsibility of users of this document to take appropriate measures to ensure the safety and health of personnel prior to the application of the document, and to determine the applicability of any other restrictions for this purpose”. We read the text of the standard in the sample of SIST EN 14111:2022 (the text of EN 14111:2022 without changes) from the cover to Clause 13 (test report) inclusive; only the informative Annex A (results of interlaboratory tests) and the bibliography remain outside the sample. We read the formula of Clause 10 from the page image, because text extraction loses it.

ACCORDING TO THE TEXT OF EN 14111:2022 (foreword, introduction, Clauses 1–13). 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) under a mandate of the European Commission and EFTA; approved by CEN on 23 April 2022, it supersedes EN 14111:2003. Technical change from the previous edition (foreword): glass weighing scoops should no longer be inserted into the flask. Introduction: the standard is based on EN ISO 3961, specifically adapted for the determination of the iodine value of FAME. Scope (1) — as on the card. References (2): EN ISO 661 (preparation of test sample of fats), EN ISO 3170 (manual sampling of petroleum liquids), EN ISO 3696 (laboratory water), EN ISO 5555 (sampling of fats). Term (3.1): iodine value — the mass of iodine absorbed by the test portion when determined according to this standard, divided by the mass of the test portion; reported as grams of iodine per 100 g of FAME. Principle (4): the test portion is dissolved in a suitable solvent mixture and Wijs reagent is added; after a specified time potassium iodide and water are added and the liberated iodine is titrated with a standardized sodium thiosulfate solution. Reagents (5): analytical grade, water of grade 3 according to EN ISO 3696; potassium iodide 100 g/l, free from iodate and iodine, freshly prepared on the day of the test; starch solution — 5 g of soluble starch in 30 ml of water added to 1000 ml of boiling water, boiled for 3 min and cooled, prepared daily without preservatives; sodium thiosulfate, standard volumetric solution c(Na2S2O3·5H2O) = 0,1 mol/l, standardized not more than seven days before use; solvent — equal volumes of cyclohexane and glacial acetic acid; Wijs reagent — iodine monochloride in acetic acid, commercially available reagent shall be used. Apparatus (6): (optional) glass weighing scoops; 500 ml Erlenmeyer flasks with ground glass stoppers, completely dried; 25 ml precision pipette; 50 ml burette graduated in 0,1 ml, class A according to ISO 385 (automatic devices of equivalent precision allowed); analytical balance accurate to ± 1 mg or better. Sampling (7): according to EN ISO 3170 or EN ISO 5555. Preparation (8): according to EN ISO 661; the test sample shall not be heated and/or filtered. Procedure (9): test portion 0,13–0,15 g (± 0,001 g) in a flask; a weighing scoop may be used; for an iodine value below 100 the mass of the test portion is to be adjusted according to EN ISO 3961 (the text uses once “should”, once “shall”); if a scoop is used, the test portion is transferred to the flask with 20 ml of solvent; add 25 ml of Wijs reagent by pipette, stopper, swirl carefully and place in the dark; blank — solvent and reagent without the test portion; 1 h in the dark; add 20 ml of potassium iodide solution and 150 ml of water; titrate with thiosulfate until the yellow colour of iodine has almost disappeared, add a few drops of starch and continue until the blue colour just disappears after very vigorous shaking; potentiometric end-point determination is permissible; the blank is titrated concurrently. Calculation (10): iodine value in g iodine/100 g FAME = 12,69 · c · (V1 − V2) / m, where c — exact thiosulfate concentration in mol/l, V1 — thiosulfate volume for the blank (ml), V2 — for the sample (ml), m — mass of the test portion (g). Expression of results (11): rounded to the nearest 1 g iodine/100 g. Precision (12): details of interlaboratory tests in Annex A, the values may not apply to other ranges and matrices; repeatability — difference of two independent results not greater than 3 g iodine/100 g (exceeded with a probability of 5 %); reproducibility — not greater than 5 g iodine/100 g. Test report (13): reference to EN 14111:2022, identification of the product, sampling method, result, deviations from the procedure, date of the test.

STATUS (catalogue cards as of 03.10.2026). The card of PN-EN 14111:2022-11 (English version, published 28-11-2022, 12 pages, price group F) has no “Withdrawn” header: Food, Agriculture and Forestry Sector, KT 92 Oilseeds, Vegetable and Animal Fats and their By-products, ICS 67.200.10, “Introduces: EN 14111:2022 [IDT]”, “Replaces: PN-EN 14111:2004 — Polish version”. The card of PN-EN 14111:2004 (Polish version, 10 pages) has the header “Withdrawn”: withdrawal date 28-11-2022, “Replaced by: PN-EN 14111:2022-11”; it introduced EN 14111:2003 [IDT]. What changed for the result: the foreword of EN 14111:2022 gives one technical change — glass weighing scoops are no longer inserted into the flask (the sample is transferred from the scoop with solvent); we have not read the text of the 2003 edition.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 03.10.2026). The number 14111 appears in 9 records at 7 laboratories: AB 009, AB 098, AB 387, AB 391, AB 484, AB 1668, AB 1679. In the current scopes on the PCA website (read 03.10.2026, issues from 19.09.2025 to 30.07.2026) AB 391, AB 484, AB 1668 and AB 1679 give the 2022-11 edition, and AB 009, AB 098 and AB 387 — the designation alone without date. The AB 009 item is set in bold italics in the PCA document — accreditation suspended at the laboratory’s request from 03.06.2026 to 30.11.2026; the items of the other six laboratories are not suspended. The “Laboratories” tab (“PN-EN 14111”) shows all 7 laboratories; checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA scopes). “Iodine value” of liquid fuels — biocomponents and liquid biofuels (FAME), by titration, at AB 1668 and in one item of AB 387 by potentiometric titration. Ranges: (111–129) g iodine/100 g at AB 1668 (exactly the precision range of the standard), (100–120) at AB 391, (105–120) and (85–130) in two items of AB 484, (50–150) g/100 g at AB 009. In the same scopes, next to it, are among others acid value (PN-EN 14104), ester content (PN-EN 14103) and oxidation stability (PN-EN 14112).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Range: precision (r = 3, R = 5 g/100 g) was established only for 111–129 g/100 g; below 111 the method is applicable but without a precision statement (1) — PCA ranges starting at 50, 85 or 100 g/100 g extend to where the standard gives no comparison criterion. Test portion: for an iodine value below 100 the mass of the test portion must be adjusted according to EN ISO 3961 (9.1) — below this limit the 0,13–0,15 g test portion is not used unchanged. Sample: the test sample shall not be heated or filtered (8). Reagents: thiosulfate standardized more than 7 days before use, potassium iodide not prepared on the day of the test or containing iodate or iodine, and starch without preservatives older than one day do not comply with 5.1–5.3; Wijs reagent shall be commercial (5.5). Procedure: the flask must be completely dry, the reaction runs in the dark for 1 h, and the blank — concurrently with the same reagent, because the result is the difference V1 − V2 (6.2, 9.2). Calculation: the result is the difference of two titrations multiplied by the thiosulfate concentration — an error in the titre passes directly into the result, and swapping V1 (blank) and V2 (sample) gives a negative value. Scoop: according to the foreword of the 2022 edition the scoop is not inserted into the flask — the sample is rinsed from it with 20 ml of solvent (9.2.1).

WHAT WE DO NOT GIVE. We do not have Annex A (results of interlaboratory tests) or the text of EN ISO 3961 — so we do not give how to adjust the test portion for an iodine value below 100, nor interlaboratory data other than r and R from Clause 12. Nor do we give requirements for the iodine value of FAME from product standards, because we have not read their text.

Method principle

The FAME sample dissolved in a mixture of cyclohexane and acetic acid is left for 1 h in the dark with Wijs reagent (iodine monochloride in acetic acid); after adding potassium iodide and water, the liberated iodine is titrated with sodium thiosulfate (starch indicator or potentiometric end point); the difference in thiosulfate volume between the blank and the sample corresponds to the iodine absorbed by the sample and gives the iodine value in g iodine/100 g.

Applications

• Fatty acid methyl esters (FAME, biodiesel, biocomponents of liquid fuels) — iodine value; 7 laboratories in PCA scopes
• FAME with iodine value below 111 g/100 g — by a method that is applicable but without a precision statement (scope of the standard)
• Quality control of FAME together with acid value, ester content and oxidation stability (neighbouring items in PCA scopes)

Key parameters

Standard

Standard number

PN-EN 14111:2022-11 (wersja angielska; EN 14111:2022 IDT)

Title (PL)

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

Title (EN)

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

Step-by-step procedure

1. Sample

   Sample according to EN ISO 3170 or EN ISO 5555, prepare according to EN ISO 661 without heating or filtering. PN-EN 14111:2022-11 current (PKN catalogue cards as of 03.10.2026).

2. Test portion and dissolution

   0,13–0,15 g (± 0,001 g) into a dry 500 ml flask (for iodine value < 100 — according to EN ISO 3961); rinse from the scoop with 20 ml cyclohexane–acetic acid mixture.

3. Reaction

   Add 25 ml Wijs reagent by pipette, stopper, swirl, 1 h in the dark; concurrently a blank without sample.

4. Titration

   Add 20 ml KI (100 g/l) and 150 ml water; titrate with 0,1 mol/l thiosulfate until the yellow colour almost disappears, add starch and titrate until the blue colour disappears after vigorous shaking (or potentiometrically).

5. Result

   Iodine value = 12,69 · c · (V1 − V2) / m, rounded to 1 g iodine/100 g; r = 3, R = 5 g/100 g for 111–129 g/100 g.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Wijs reagent (iodine monochloride in acetic acid) is corrosive and cyclohexane is flammable — work in a fume hood, with gloves and goggles; the standard warns that it does not address all hazards (scope)
• Glacial acetic acid is corrosive and flammable — keep away from ignition sources

Frequently asked questions