🧵 Formaldehyde extracted from melamine-formaldehyde articles intended for contact with food — extraction with water, 3 % acetic acid and 10 % ethanol, spectrophotometric determination (procedure A with chromotropic acid, B with acetylacetone); PN-EN ISO 4614

Materials and NDT PN-EN ISO 4614

Overview

WHAT THE STANDARD COVERS. ISO 4614:1977 (clause 1): a method for the determination of formaldehyde extracted from articles made of melamine-formaldehyde moulding materials intended to come into contact with food and beverages. Principle (clause 2): liquids simulating typical food and beverage constituents are brought into contact with the article under specified conditions, the formaldehyde in the liquid is determined and the quantity extracted per unit area of contact surface is calculated; two procedures are given for determining formaldehyde in the liquid. The standard was prepared by committee ISO/TC 61 "Plastics" (vote in 1975; against — USA and USSR, on technical grounds). The "Scope" field of the PKN card of PN-EN ISO 4614:2005, in full (our translation): "Two spectrophotometric methods are specified for determining the formaldehyde content in a liquid that simulates foods and beverages in contact, under specified conditions, with mouldings from a sample of the plastic" (without a full stop on the card).

PROCEDURE (ISO 4614:1977, clauses 3–10 — full text of the standard read). • Test specimens (4): articles in the form of containers, e.g. cups or bowls, with an internal surface area of 150–250 cm² and a capacity of 150–250 cm³; the ratio of the wetted surface area (cm²) to the volume of liquid (cm³) shall be 0.75–1. Six specimens — two determinations with each of the three liquids. • Extraction liquids (5): distilled or deionized water; acetic acid — a solution of 30 g/l of glacial acetic acid in distilled water; ethanol — a 100 g/l solution in distilled water. • Extraction (6): rinse the container with warm distilled water and dry it thoroughly; pour an appropriate quantity of the liquid at 80 °C into the container at room temperature, cover with a watch glass and leave in air at room temperature for 30 min; transfer the extract (without rinsing) to a 250 ml conical flask, stopper, cool in a bath to 20 ± 0.5 °C and immediately determine formaldehyde by procedure A or B. • Procedure A (7) — chromotropic acid: formaldehyde-free reagents; solution of the disodium salt of chromotropic acid (0.50 g in 100 ml of water, fresh daily); concentrated sulfuric acid 81 % (m/m); formaldehyde stock solution from technical formalin (approx. 400 g/l; 25.0 ml in 1000 ml; concentration according to ISO 2227; not older than one week), working solutions A and B (B approx. 10 mg/l) in the extraction liquid, prepared immediately before use. Calibration curve: six solutions of approx. 10–1 µg/ml (1.0 ml each), to each 1.0 ml of chromotropic acid solution and slowly, with shaking, 8.0 ml of sulfuric acid; bath at 60 °C for 30 min, then 45–60 min at room temperature; absorbance at 570 nm in a 10 mm cell against distilled water; blank with the extraction liquid; the graph shall be a straight line through the origin. Determination: 1.0 ml of extract in the same way; range 1.0–10 µg/ml, above 10 µg/ml the extract is diluted. • Procedure B (8) — acetylacetone: reagent of 150 g of ammonium acetate, 3.0 ml of glacial acetic acid and 2.0 ml of acetylacetone in 1000 ml (fresh daily); calibration curve: six solutions of approx. 8–0.5 µg/ml (5.0 ml each), to each 5 ml of reagent; bath at 60 °C for 20 min, then 45–60 min at room temperature; absorbance at 415 nm in a 10 mm cell. Determination: 5.0 ml of extract + 5.0 ml of reagent; range 0.5–8.0 µg/ml, above 8 µg/ml the extract is diluted. • Apparatus (7.2, 8.2): test tubes with ground-glass joints, water bath at 60 °C, cooling bath at 20 ± 0.5 °C, spectrophotometer for the visible range with 10 mm glass cells, class A volumetric glassware (pipettes according to ISO 648, 50 ml burette according to ISO/R 385, flasks according to ISO 1042) and two 5 ml burettes. • Result (9): for each liquid two individual results: formaldehyde extracted in µg/ml of liquid = a × f and in µg/cm² of article surface = a × V × f / A, where a — formaldehyde in the test solution (µg/ml), f — dilution factor, V — volume of liquid (ml), A — area of contact with the liquid (cm²). • Test report (10): reference to the standard, identification of the article, description of the specimen (design, capacity, ratio of wetted surface area to volume of liquid), moulding conditions (curing time and temperature), the procedure used (A or B), individual results.

STATUS (state of the PKN cards on 10.10.2026). The card of PN-EN ISO 4614:2005 (Polish version) carries no withdrawal label: title "Tworzywa sztuczne -- Tłoczywa melaminowo-formaldehydowe -- Oznaczanie ekstrahowalnego formaldehydu" (Plastics — Melamine-formaldehyde mouldings — Determination of extractable formaldehyde; our translation), publication 06-01-2005, 10 pages, Sector of Chemistry, KT 141 Plastics, "Replaces: PN-EN ISO 4614:2002 - English version", "Introduces: EN ISO 4614:1999 [IDT], ISO 4614:1977 [IDT]", ICS 83.080.10. The content of the Polish standard is therefore the text of ISO 4614 of 1977. In the PKN search engine (query "ISO 4614", 10.10.2026) there are also cards PN-EN 4614 — these are different (aerospace) standards, not to be confused with this one.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database of 10.10.2026 and current PCA documents read on 10.10.2026). The number 4614 appears in 9 records at 9 laboratories: AB 311, AB 343, AB 379, AB 438, AB 451, AB 486, AB 515, AB 562 and AB 910; the standard is present in all 9 current PCA documents, no entry is suspended. Forms: "PN-EN ISO 4614:2005" (7 laboratories, five of them with a clause or procedure added), "PN-EN ISO 4614 :2005" with a space (AB 311) and "PN-EN ISO 4614" without a year (AB 910). The "Laboratories" tab ("PN-EN ISO 4614") shows all 9 laboratories.

WHAT THE LABORATORIES TEST (copy and PCA documents). All — by the spectrophotometric method. Quantity: migration or content of extracted formaldehyde. Procedure: B (acetylacetone) stated directly by AB 379 ("met. B") and AB 438 ("procedure B"), through clause 8 of the standard by AB 343 ("clauses 8 and 9"), AB 451 and AB 515; the others do not state it. Liquid: 3 % acetic acid at AB 311, AB 379, AB 486 and AB 515 (in the test description), and in the measuring ranges also at AB 343 (besides water and 10 % ethanol — all three liquids of the standard) and AB 438 (besides 10 % ethanol; the test is described as migration "into aqueous food simulants"); AB 451, AB 562 and AB 910 do not state the liquid. Subject: melamine-formaldehyde moulding materials and articles, plastics for food contact (AB 451), melamine articles (AB 515), and at AB 910 — toys, children's articles, cutlery and tableware.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — one liquid instead of three: the standard provides for two determinations with each of the three liquids (water, 3 % acetic acid, 10 % ethanol); a result with acetic acid only is a result according to the standard in a narrower scope and has to be stated as such. Second — extraction conditions: liquid poured in at 80 °C and 30 min at room temperature are the conditions of this standard; other conditions (e.g. repeated extractions at elevated temperature required by the regulations on food contact materials — we have not read those regulations here) give a different number. Third — surface area and volume: the ratio of wetted surface area to volume of 0.75–1 and the result in µg/cm² require a measured contact area A; a result in µg/ml only cannot be converted to a different article geometry. Fourth — range of the curve: above 10 µg/ml (A) or 8 µg/ml (B) the extract has to be diluted and the factor f taken into account. Fifth — subject: the standard concerns articles made of melamine-formaldehyde moulding materials for food; application to toys and children's articles (AB 910) goes beyond its scope.

WHAT WE DO NOT GIVE. Standard read in full; we do not give requirements (formaldehyde migration limits) — they result from the regulations on materials intended to come into contact with food, not from this standard — or the method of ISO 2227 for determining formaldehyde in formalin.

Method principle

A simulant liquid at 80 °C (water, 30 g/l acetic acid or 100 g/l ethanol) is poured into the article made of melamine-formaldehyde moulding material, left for 30 min covered at room temperature, the extract is cooled to 20 °C and formaldehyde in it is determined spectrophotometrically: with chromotropic acid in sulfuric acid (570 nm, procedure A, 1–10 µg/ml) or with acetylacetone and ammonium acetate (415 nm, procedure B, 0.5–8 µg/ml); the result in µg/ml of liquid and µg/cm² of contact surface (ISO 4614:1977, clauses 2, 5–9).

Applications

• Articles made of melamine-formaldehyde moulding materials intended for contact with food and beverages — cups, bowls, tableware (ISO 4614:1977, clauses 1 and 4)
• Quality control of batches of articles and documentation of compliance of food contact materials
• In the accreditation scopes: 9 laboratories, all spectrophotometrically; procedure B stated directly or through clause 8 at five

Key parameters

Standard

Standard number

PN-EN ISO 4614:2005 (wersja polska; wprowadza EN ISO 4614:1999 [IDT] oraz ISO 4614:1977 [IDT])

Title (PL)

Tworzywa sztuczne — Tłoczywa melaminowo-formaldehydowe — Oznaczanie ekstrahowalnego formaldehydu

Title (EN)

Plastics — Melamine-formaldehyde mouldings — Determination of extractable formaldehyde

Step-by-step procedure

1. Preparation of specimens

   Six containers (two for each liquid) with an internal surface area of 150–250 cm² and a capacity of 150–250 cm³; rinse with warm distilled water and dry thoroughly.

2. Extraction

   Pour in the liquid at 80 °C (water, acetic acid 30 g/l or ethanol 100 g/l) so that the ratio of wetted surface area to volume is 0.75–1; cover with a watch glass, 30 min at room temperature.

   ⏱ Time: 30 min • 🌡 Temperature: liquid 80 °C, then room temperature

3. Cooling the extract

   Transfer without rinsing to a 250 ml conical flask, stopper, cool to 20 ± 0.5 °C and determine immediately.

4. Calibration curve

   Six formaldehyde solutions in the extraction liquid: A — approx. 10–1 µg/ml, B — approx. 8–0.5 µg/ml; colour reaction as for the sample; straight line through the origin; blank.

5. Determination

   A: 1.0 ml of extract + 1.0 ml of chromotropic acid + 8.0 ml of H2SO4, 60 °C 30 min, 45–60 min, 570 nm. B: 5.0 ml of extract + 5.0 ml of acetylacetone reagent, 60 °C 20 min, 45–60 min, 415 nm. Above the range of the curve — dilute.

6. Result and report

   µg/ml = a × f; µg/cm² = a × V × f / A; two results for each liquid; in the report procedure A or B, description of the article and moulding conditions. PN-EN ISO 4614:2005 current (state of the PKN card on 10.10.2026).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Formaldehyde and formalin — carcinogenic and sensitizing; work in a fume cupboard, gloves
• Sulfuric acid 81 % added to an aqueous solution generates heat — add slowly, goggles and gloves
• Acetylacetone — flammable and harmful; fume cupboard

Frequently asked questions