🧵 Detection of azo colorants which may release 4-aminoazobenzene in textiles — the specimen (disperse dyes: after extraction with xylene; other colorants: directly) is reduced with sodium dithionite in 2 % sodium hydroxide solution at (40 ± 2) °C for 30 min, 4-aminoazobenzene is transferred into t-butyl methyl ether with sodium chloride added and determined chromatographically (TLC/HPTLC, HPLC-DAD/MS, GC-FID/MS, CE-DAD) with confirmation by a second method; applied after a pre-fail result for aniline according to ISO 14362-1, PN-EN ISO 14362-3

Materials and NDT PN-EN ISO 14362-3

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in the iTeh sample of ISO 14362-3:2017 (English text): from the title page through the contents, foreword and Clauses 1–11 (up to and including the test report) on page 7. Outside the sample remain Annexes A (chromatographic conditions), B (calculation), C (reliability of the method) and D (interpretation of results). The title page and European foreword of EN ISO 14362-3:2017 we read in the iTeh sample of SIST EN ISO 14362-3:2017.

ACCORDING TO THE TEXT OF ISO 14362-3:2017 AND THE FOREWORD OF EN ISO 14362-3:2017. According to the ISO foreword the document was prepared by CEN/TC 248 “Textiles and textile products” in collaboration with ISO/TC 38 “Textiles” under the Vienna Agreement, and according to the European foreword — by ISO/TC 38 in collaboration with CEN/TC 248, the secretariat of which is held by BSI; CEN approved EN ISO 14362-3:2017 on 21.12.2016, and it superseded EN 14362-3:2012. The first edition of ISO 14362-3 (2017-02) replaced ISO 24362-3:2014; the foreword lists the changes: a new Clause 3 and renumbering, clarification of the preparation and use of the sodium dithionite solution (7.1) and changes to the procedure, including xylene instead of chlorobenzene (because of lower toxicity and lower adverse environmental effect). Scope (1): azo colorants able to form 4-aminoazobenzene generate under the conditions of ISO 14362-1 the amines aniline and 1,4-phenylenediamine, and the presence of such colorants cannot be reliably ascertained without additional information (e.g. the chemical structure of the colorant used) or without a special procedure; the document supplements ISO 14362-1 and describes a special procedure to detect the use, in commodities, of azo colorants which may release 4-aminoazobenzene — accessible to the reducing agent without extraction (particularly textiles made of cellulose and protein fibres, e.g. cotton, viscose, wool, silk) and accessible by extracting the fibres (e.g. polyester, imitation leather); for certain fibre blends both routes (9.3 and 9.4) may need to be applied; the procedure also detects 4-aminoazobenzene (Solvent Yellow 1) present in the commodity as free amine, without reduction; the use of colorants releasing other aromatic amines from Annex XVII of REACH (Regulation (EC) No 1907/2006) cannot be determined quantitatively with this method. References (2): ISO 3696 and ISO 14362-1:2017. Clause 3 contains no terms. General (4): Table 1 — 4-aminoazobenzene, No. 22, CAS 60-09-3, index number 611-008-00-4, EC number 200-453-6, an amine proscribed under REACH. Principle (5): a specimen is taken from a coloured part of the article and tested by the method of colorant extraction for disperse dyes and/or the method of direct reduction for the other classes of colorants (pigments and/or dyes) according to ISO 14362-1; the specimen or the residue of extraction is treated with sodium dithionite in alkaline solution at 40 °C in a closed vessel, the released 4-aminoazobenzene is transferred by liquid–liquid extraction into a t-butyl methyl ether phase, and an aliquot of it is analysed chromatographically; detection by one chromatographic method is confirmed by at least one other method. Reagents (7): sodium dithionite solution 200 mg/ml freshly prepared — rested in a closed vessel for (55 ± 1) min, transferred into an open beaker, rested for 5 min (−0/+5 min) and used within 10 min; sodium hydroxide 2 % (mass fraction); methanol; xylene (mixture of isomers); t-butyl methyl ether; sodium chloride; 4-aminoazobenzene of the highest available defined purity; internal standards for GC, e.g. for GC-MS naphthalene-d8, 2,4,5-trichloroaniline or anthracene-d10, solution 10,0 µg/ml in ether; 4-aminoazobenzene solution in methanol 500 µg/ml; grade 3 water according to ISO 3696. Apparatus (8): extraction apparatus (coil condenser NS 29/32, hook of inert material, 100 ml round-bottom flask, heating source; according to the note similar apparatus may be used if it gives the same results), ultrasonic bath, 20–50 ml reaction vessel of heat-resistant glass with tight closure, heating source (40 ± 2) °C, vacuum rotary evaporator with vacuum control (or e.g. a water bath with nitrogen flow), centrifuge above 3000 r/min, pipettes, shaker ensuring efficient mixing of the phases (according to the note a horizontal shaker with a frequency of at least 5 s⁻¹ and a path of 2–5 cm has been found suitable), chromatograph: TLC or HPTLC, HPLC with gradient elution and DAD or MS detector, GC with FID or MS detector, or capillary electrophoresis with DAD (with a 0,2 µm PTFE membrane filter). Procedure (9): the document is applied to a specimen which in ISO 14362-1:2017 (procedure 10.1 or 10.2) gave a pre-fail result for aniline and 1,4-phenylenediamine or only for aniline — with a result from 10.1 route 9.3 is chosen, with a result from 10.2 — route 9.4; in multi-coloured fabrics the individual colours are tested separately as far as possible, and different qualities of the article (fibre and/or colour) — separately; specimen with a total mass of 1 g, cut into strips (apparatus 8.1) or small pieces. Route with extraction (9.3): another specimen of the same composition for 30–40 min above 25 ml boiling xylene until the drops from the specimen are colourless; the cooled extract is evaporated to dryness at 45–75 °C and the residue is transferred quantitatively to the reaction vessel with 7 ml methanol in total using ultrasound; an aliquot of this methanolic solution may be used immediately for direct determination of a disperse colorant releasing 4-aminoazobenzene (e.g. Disperse Yellow 23) by LC-DAD-MS. Route without extraction (9.4): the cut specimen is put directly into the reaction vessel. Reduction (9.5): 9 ml sodium hydroxide solution, closing and vigorous shaking, then 1,0 ml sodium dithionite solution, closing again and shaking, immediately kept without shaking at (40 ± 2) °C for exactly 30 min and cooled to 20–25 °C within 1 min. Separation (9.6): 5 ml t-butyl methyl ether or internal standard solution and 7 g sodium chloride, shaking for 45 min; it is not recommended that more than 5 min elapse between cooling and shaking; centrifuging is recommended for phase separation; an aliquot of the ether phase is transferred into a vial which is closed immediately; changing the solvent or evaporating to dryness without controlled conditions may cause substantial loss of 4-aminoazobenzene — if necessary the extract is concentrated to about 1 ml (not to dryness) under slight vacuum at not more than 50 °C, and the remainder is removed with a weak flow of inert gas; changing the solvent is avoided where possible; owing to the matrix 4-aminoazobenzene may have poor stability, and delays risk severe losses; if the analysis cannot be completed within 24 h, the solution is kept below −18 °C. Calibration (9.7): without extraction — 100 µl of 4-aminoazobenzene solution and 5 ml ether (or internal standard solution), as the recovery in phase partition is 95–100 %; when detected above 5 mg/kg, quantification is made with a calibration curve, e.g. as in ISO 14362-1; with extraction — 100 µl of the solution in a matrix of 6,9 ml methanol, 9 ml sodium hydroxide, 1 ml water, 7 g sodium chloride and 5 ml ether, shaken for 45 min; according to the note recoveries can differ with a high methanol content, and then a calibration curve of at least three points in a methanol-containing matrix is needed. Check of the system (9.8): 100 µl of 4-aminoazobenzene solution (with 6,9 ml methanol for the extraction route) is treated according to 9.5 — recovery at least 60 %. Analysis (9.9): techniques from 8.9 or other validated methods; detection by one method is confirmed by at least one other, and the result is positive only if both methods give a positive result. Calculation (10): usually by software, manually according to Annex B; reliability — Annex C. Report (11): at least reference to ISO 14362-3, kind, origin and designation of the specimen, dates of receipt and analysis, sampling and preparation procedure (9.3 or 9.4), detection and quantification method, result as level and detection limit of 4-aminoazobenzene in mg/kg; concentrations below 30 mg/kg should be interpreted with care (Annex D).

STATUS (as of 03.10.2026). The PKN search (term “PN-EN ISO 14362-3”, 03.10.2026) shows PN-EN ISO 14362-3:2017-04 (English version, “Introduces: EN ISO 14362-3:2017 [IDT], ISO 14362-3:2017 [IDT]”) without a withdrawal note and PN-EN 14362-3:2012 (English version), withdrawn and replaced by PN-EN ISO 14362-3:2017-04. In the iTeh catalogue (read on 03.10.2026) ISO 14362-3:2017 has the status “Published”, stage 90.93 (standard confirmed) since 20.07.2022.

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 14362-3 appears in 5 records at 5 laboratories: AB 062, AB 077, AB 403, AB 910, AB 1573. In the current PCA documents (read on 03.10.2026, issues from 06.11.2025 to 11.08.2026) the number appears in 5 rows — one at each; in each of the five documents the number of page markers equals the number of PDF pages, without repetitions; a search of all 1291 PCA documents downloaded from BIP on 03.10.2026 found no laboratories outside the database copy (17 laboratories on the list have no link to a scope document on BIP). The form “PN-EN ISO 14362-3:2017-04” (AB 062, AB 077, AB 403, AB 1573) and “PN-EN ISO 14362-3” without year in one cell with 11 other reference documents (AB 910). None of these items is suspended. The “Laboratories” tab (term “PN-EN ISO 14362-3”) shows all 5 laboratories — checked with a tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). Object: textiles, fabrics, yarn, clothing and finished products (AB 062; at AB 077 also imitation leather), textile products (AB 403), textile fabrics — woven, knitted, yarn, nonwovens, coated products, clothing, finished products (AB 1573), toys, children’s articles and materials for them, paints, textile products, clothing (AB 910, item in the flexible scope of accreditation). Characteristic: presence and content of 4-aminoazobenzene reduced from azo colorants (AB 062), content of 4-aminoazobenzene reduced from azo colorants (AB 077) or released from azo colorants (AB 403, AB 1573), content of free amines and amines released from azo colorants (AB 910). Ranges: (15–300) mg/kg (AB 062), (20–100) mg/kg (AB 077, AB 1573), (30–655) mg/kg (AB 403). Technique: TLC and HPLC-DAD (AB 062), GC-NPD, GC-MS and HPLC-DAD (AB 077), HPLC-DAD (AB 403, AB 910), GC-FID and GC-MS (AB 1573).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the sequence: the method is applied after a pre-fail result for aniline (with or without 1,4-phenylenediamine) in ISO 14362-1, and the route is chosen according to the procedure that gave this result (9.1). With dithionite: the solution has a specified resting and use time — 55 min in a closed vessel, 5–10 min in an open beaker, then at most 10 min (7.1). With reduction: (40 ± 2) °C for exactly 30 min without shaking and rapid cooling (9.5). With concentration: not to dryness, at most 50 °C — otherwise substantial loss of analyte (9.6). With storage: analysis within 24 h or the solution below −18 °C (9.6). With checking: recovery at least 60 % (9.8). With the result: positive only when confirmed by a second method (9.9), and concentrations below 30 mg/kg should be interpreted with care (11).

WHAT WE DO NOT GIVE. We did not read the chromatographic conditions (Annex A), the calculation formula (Annex B), the reliability data (Annex C) or the guidance on interpretation of results (Annex D). We do not give limit values for products.

Method principle

Coloured textile material (1 g) — for disperse dyes the residue of xylene extraction transferred with methanol, for other colorants the material directly — is reduced with sodium dithionite in 2 % sodium hydroxide solution in a closed vessel at (40 ± 2) °C for 30 min. The released 4-aminoazobenzene is transferred into t-butyl methyl ether (with sodium chloride, shaking 45 min) and determined chromatographically; the result is positive only after confirmation by a second method. The method is applied when ISO 14362-1 gave a pre-fail result for aniline.

Applications

• Textiles made of cellulose and protein fibres (cotton, viscose, wool, silk) — without extraction; polyester and imitation leather — with colorant extraction (1)
• Confirmation of the use of azo colorants releasing 4-aminoazobenzene after a pre-fail result for aniline in ISO 14362-1 (1, 9.1)
• Textiles, clothing, imitation leather, toys and children’s articles — items in the accreditation scopes of 5 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN ISO 14362-3:2017-04

Title (PL)

Tekstylia — Metody oznaczania niektórych amin aromatycznych pochodzących z barwników azowych — Część 3: Wykrywanie zastosowania niektórych barwników azowych, które mogą uwalniać 4-aminoazobenzen

Title (EN)

Textiles — Methods for determination of certain aromatic amines derived from azo colorants — Part 3: Detection of the use of certain azo colorants, which may release 4-aminoazobenzene

Step-by-step procedure

1. Qualification and specimen

   Pre-fail result for aniline in ISO 14362-1; 1 g specimen, colours and qualities of the article separately (9.1, 9.2). PN-EN ISO 14362-3:2017-04 without a withdrawal note (03.10.2026).

2. Extraction (disperse dyes)

   30–40 min above 25 ml boiling xylene, evaporation at 45–75 °C, residue into the vessel in 7 ml methanol (9.3).

3. Reduction

   9 ml NaOH, 1,0 ml dithionite, (40 ± 2) °C for 30 min, rapid cooling (9.5).

4. Separation

   5 ml ether and 7 g NaCl, shaking 45 min, centrifuging, aliquot of the ether phase into a closed vial; analysis within 24 h or storage below −18 °C (9.6).

5. Determination and result

   Chromatography with confirmation by a second method; control recovery ≥ 60 %; result and detection limit in mg/kg (9.8, 9.9, 11).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• 4-aminoazobenzene is classified as a substance known or suspected to be a human carcinogen — handling and disposal according to national regulations (6)
• Xylene, methanol and t-butyl methyl ether — flammable solvents; work in a fume hood

Frequently asked questions