BS EN 16711-1:2015 Incorporating corrigendum November 2015 BSI Standards Publication Textiles — Determination of metal content Part 1: Determination of metals using microwave digestion BS EN 16711-1:2015 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 16711-1:2015 The UK participation in its preparation was entrusted to Technical Committee TCI/80, Chemical testing of textiles A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2015 Published by BSI Standards Limited 2015 ISBN 978 580 92482 ICS 59.060.01 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2015 Amendments/corrigenda issued since publication Date Text affected 30 November 2015 This corrigendum replaces the main text of the document with the correct standard BS EN 16711-1:2015 EN 16711-1 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM November 2015 ICS 59.060.01 English Version Textiles - Determination of metal content - Part 1: Determination of metals using microwave digestion Textiles - Détermination de la teneur en métaux Partie 1: Dosage des métaux par minéralisation par micro-ondes Textilien - Bestimmung von Metallen - Teil 1: Bestimmung von Metallen mittels Mikrowellenaufschluss This European Standard was approved by CEN on September 2015 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 16711-1:2015 E BS EN 16711-1:2015 EN 16711-1:2015 (E) Contents Page European foreword Scope Normative references Principle 4 Apparatus Reagents 6.1 6.2 6.3 6.4 6.4.1 6.4.2 6.4.3 Test specimen sampling Natural and man-made textiles Garment components with painted and other similar surface coatings Metallic products Non-metal products General Ceramics, glass and crystal and other siliceous materials Plastics, polymers ( includes prints and coatings other than 6.2) and other nonsiliceous materials 7.1 7.2 7.3 7.4 7.4.1 7.4.2 7.5 7.6 Procedure Digestion of natural and man-made textiles, and coated fabrics Digestion of paint and other similar surface coatings Digestion of metallic products Digestion of non-metal products Ceramics, glass and crystal and other siliceous materials Plastics, polymers and other non-siliceous materials Determination of metals Reporting of results 8 Reliability of the method 9 Test report Annex A (informative) Laboratory microwave procedure 10 A.1 Cleaning of polytetrafluoroethylene glassware and vessels 10 A.2 Sample preparation (digestion) 10 Annex B (informative) Procedure characteristics 12 B.1 Trueness complying with ISO 5725-4 12 B.2 System precision 13 B.3 Limit of detection and limit of quantification 13 Bibliography 14 BS EN 16711-1:2015 EN 16711-1:2015 (E) European foreword This document (EN 16711-1:2015) has been prepared by Technical Committee CEN/TC 248 “Textiles and textile products”, the secretariat of which is held by BSI This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2016, and conflicting national standards shall be withdrawn at the latest by May 2016 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights EN 16711, Textiles — Determination of metal content is composed of the following parts: — Part 1: Determination of metals using microwave digestion; — Part 2: Determination of metals extracted by acidic artificial perspiration solution According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom BS EN 16711-1:2015 EN 16711-1:2015 (E) Scope This European Standard specifies a procedure for determination of metals, in particular antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni) in natural and man-made textiles, including coated fabrics and garment components (e.g buttons, zips, etc.) after microwave digestion Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 1233, Water quality — Determination of chromium — Atomic absorption spectrometric methods EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696) EN ISO 11885, Water quality — Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (ISO 11885) EN ISO 12846, Water quality — Determination of mercury — Method using atomic absorption spectrometry (AAS) with and without enrichment (ISO 12846) EN ISO 15586, Water quality — Determination of trace elements using atomic absorption spectrometry with graphite furnace (ISO 15586) EN ISO 17294-2, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-MS) — Part 2: Determination of 62 elements (ISO 17294-2) EN ISO 17852, Water quality — Determination of mercury — Method using atomic fluorescence spectrometry (ISO 17852) ISO 8288, Water quality — Determination of cobalt, nickel, copper, zinc, cadmium and lead — Flame atomic absorption spectrometric methods Principle The total metal content is determined after microwave digestion Analysis is performed with appropriate analytical techniques of atomic absorption, inductively coupled plasma and mass spectrometry (e.g ICP-MS, ICP-OES, AAS, cold vapor atomic absorption spectrometry, etc.) Apparatus General laboratory equipment for analytical chemistry In addition, the following is required: 4.1 4.2 4.3 Analytical balance, readability 0,000 g Microwave digestion system with appropriate high pressure vessels Appropriate digestion vessels, e.g of polytetrafluoroethylene (PTFE) BS EN 16711-1:2015 EN 16711-1:2015 (E) Reagents Unless otherwise specified, analytical grade chemicals shall be used 5.1 5.2 5.3 5.4 5.5 Nitric acid, ω(HNO3) = 65 % Sulphuric acid, ω(H2SO4) = 96 % Hydrofluoric acid, ω(HF) = 48 % Grade water, complying with EN ISO 3696 Hydrogen peroxide, ω(H2O2) = 30 % 5.6 Metal standard solutions for calibration of the analytical systems complying with EN 1233, EN ISO 11885, EN ISO 12846, EN ISO 15586, EN ISO 17294-2, EN ISO 17852 or ISO 8288 5.7 Dilution solution, 1,2 ml nitric acid (5.1) is made up to 100 ml with water (5.4) Test specimen sampling 6.1 Natural and man-made textiles Cut from the textile specimen (with a sharp pair of scissors made of noncorrosive material, preferably of ceramics) a representative subsample of approximately 0,5 g and record the mass to the nearest 0,1 mg If the textile article is composed of several parts of textile products, such as knitted cuffs or lining, all the different types of materials have to be tested as a representative composite specimen with equal parts of each component Select the number of parts that can be collected as a composite specimen in relation to the detection and quantification limits of the instrumental equipment Weigh out materials that cannot be separated as one specimen Consider also different colours of the material for sampling Avoid any contact with metal articles, especially in wet conditions or with corrosive surfaces 6.2 Garment components with painted and other similar surface coatings For products coated with paint or a similar surface coating, remove and digest the coating separately from the substrate material Care should be taken to remove as little of the substrate as possible It may be necessary to add a few drops of a solvent, such as dichloromethane, to soften the paint and aid in its removal from the substrate If used, such solvent shall be evaporated fully prior to analysis The scraped paint shall be finely divided to help in the digestion Scrape approximately 100 mg to 200 mg of paint from the product If it is not possible to collect this much paint it may be necessary to combine more than one unit of such product to collect sufficient paint 6.3 Metallic products When preparing a sample, the laboratory shall make every effort to assure that the aliquot removed from a component part of a sample is representative of the component to be tested, and is free of contamination If the item is coated with paint or a similar surface coating, the coating shall be removed and analysed, separately from the base metal, for metal content as described in 6.2 Component parts of children’s products, including metal jewellery items, generally weigh several grams or more, and an aliquot (with no paint or similar surface coating) will have to be obtained Samples should be cut or ground into many small pieces to increase the rate of dissolution If used, grinding apparatus (such as a rotary grinding tool with disposable grinding bits) must be thoroughly cleaned to prevent cross-contamination BS EN 16711-1:2015 EN 16711-1:2015 (E) 6.4 Non-metal products 6.4.1 General The general approach is to grind or cut any accessible component part of a sample into small pieces or a powder; digest an aliquot completely in nitric acid or, for siliceous products, in a combination of hot, concentrated nitric and hydrofluoric acids 6.4.2 Ceramics, glass and crystal and other siliceous materials Ceramic items generally weigh several grams or more, and consist of the base ceramic with a glaze and decoration fired on The metals in ceramics are generally in the glaze or decoration When analysing ceramics or glass, the entire item including the glaze, decoration, and ceramic base material should be ground in a cryogenic mill and 100 mg to 200 mg of the ground ceramic/glass powder weighed in an appropriate microwave vessel If used, the grinding apparatus must be thoroughly cleaned to prevent cross-contamination 6.4.3 Plastics, polymers ( includes prints and coatings other than 6.2) and other non- siliceous materials Cut the test specimen into small pieces Hard to digest plastics may need to be cryomilled to get a finer powder Ensure the milling apparatus is thoroughly clean between test specimens to avoid crosscontamination Procedure 7.1 Digestion of natural and man-made textiles, and coated fabrics Perform a microwave digestion using a mixture of nitric acid and hydrogen peroxide, examples are given in Annex A Other digestion methods may be used if the same results are obtained Weigh out 0,1 g to 0,5 g of the finely cut specimen (record the mass to the nearest 0,1 mg) and put into a clean PTFE vessel Add ml of water (5.4) for surface wetting and subsequently 10 ml nitric acid (5.1) and ml hydrogen peroxide (5.5) (see Table A.3) or ml nitric acid (5.1) and 2,5 ml hydrogen peroxide (5.5) (see Table A.4) Care shall be taken to ensure that the specimen is wetted with acid, since otherwise burning of the sample material may occur The filled volume of the PTFE vessels should not exceed 30 % to 40 % of the total volume Residues resulting from pigments or admixtures of titanium oxide in polyester and polyamide fibres have to be removed by filtration 7.2 Digestion of paint and other similar surface coatings Weigh 0,1 g to 0,2 g (record the mass to the nearest 0,1 mg) of the paint into a clean liner of the microwave digestion vessel Carefully add at least ml of concentrated nitric acid or extraction solution (made with 60 ml HNO3 conc and 180 ml HCl conc / l water grade Prepare also a digestion blank with the samples Use a certified reference material if available (e.g such as NIST SRM 2581 or 2582 for lead determination) to control the digestion The result should be between ± 15 % of the true value Seal the vessels and load into the microwave oven according to the manufacturer’s instructions Programme the microwave digestion system using a programme with enough temperature or power to digest the sample (check this with the certified reference material) At the end of the digestion period, remove the vessels from the microwave oven, place them in a fume hood, and allow the solutions to cool to room temperature BS EN 16711-1:2015 EN 16711-1:2015 (E) Carefully open the vessels (pay attention to the gas pressure that may be present inside the vessels) Quantitatively transfer the liquid contents of each vessel to a 50 ml volumetric flask (the size may be adjusted and will depend on the required limit) Carefully rinse each vessel with grade water into the volumetric flask and bring to volume with water (be sure that the liquid temperature is near room temperature before making the volume up to the mark) Seal each volumetric flask with a stopper and mix thoroughly 7.3 Digestion of metallic products Weigh out 0,1 g to 0,2 g (record the mass to the nearest 0,1 mg) piece of metal item into an appropriate microwave vessel, equipped with a controlled pressure relief mechanism Add ml of concentrated nitric acid, and ml of concentrated hydrochloric acid to each vessel Wait for the initial reaction of the acid and sample at room temperature to be complete (to the point of no obvious fuming or bubbling) before sealing the vessels Seal vessels in accordance with the manufacturer’s instructions Prepare also a digestion blank with the samples Use a certified reference material if available (e.g such as NIST SRM 54d, 1728 for lead determination) to control the digestion The result should be between +/- 15 % of the true value Seal the vessels and load into the microwave oven according to the manufacturer’s instructions Programme the microwave digestion system using a programme with enough temperature or power to digest the sample (check this with the certified reference material) At the end of the digestion period, remove the vessels from the microwave oven, place them in a fume hood, and allow the solutions to cool to room temperature Carefully open the vessels (pay attention to the gas pressure that may be present inside the vessels) Quantitatively transfer the liquid contents of each vessel to a 50 ml volumetric flask (the size may be adjusted and will depend on the required limit) Carefully rinse each vessel with grade water into the volumetric flask and bring to volume with water (be sure that the liquid temperature is near room temperature before making the volume up to the mark) Seal each volumetric flask with a stopper and mix thoroughly 7.4 Digestion of non-metal products 7.4.1 Ceramics, glass and crystal and other siliceous materials Weigh out a 0,1 g to 0,5 g (record the mass to the nearest 0,1 mg) piece of ceramic, glass or crystal item into an appropriate microwave vessel equipped with a controlled pressure relief mechanism Add ml of concentrated nitric acid and ml of concentrated hydrofluoric acid to each vessel Wait for completion of the initial reaction of the acid and the sample before sealing the vessels Seal the vessels in accordance with the manufacturer’s instructions Prepare also a digestion blank with the samples Use a certified reference material if available (e.g such as NIST SRM 89 and 610, leaded glass, for lead determination) to control the digestion The result should be between +/- 15 % of the true value Programme the microwave digestion system using a programme with enough temperature or power to digest the sample (check this with the certified reference material) At the end of the digestion period, remove the vessels from the microwave oven, place them in a fume hood, and allow the solutions to cool to room temperature Carefully open the vessels (pay attention to the gas pressure that may be present inside the vessels) If the analysis is to be carried out using ICP equipment, add 30 ml of % (w/w) boric acid to each vessel to complex with the fluoride to protect the ICP quartz plasma torch Quantitatively transfer the sample BS EN 16711-1:2015 EN 16711-1:2015 (E) to a 50 ml plastic volumetric flask or disposable volumetric digestion cup Dilute to 50 ml with deionized water 7.4.2 Plastics, polymers and other non-siliceous materials Weigh out 150 mg of the milled or cut plastic into an appropriate microwave vessel equipped with a controlled pressure relief mechanism Record the actual weight to the nearest 0,1 mg At room temperature, add 10 ml of concentrated nitric acid and ml of hydrogen peroxide to each vessel Wait for completion of the initial reaction of the acid and the sample before sealing the vessels Seal the vessels in accordance with the manufacturer’s instructions Prepare also a digestion blank with the samples Use a certified reference material if available (e.g such as ERM®-EC680k2 and EC681k, low density polyethylene for lead and cadmium determination) to control the digestion The result should be between +/- 15 % of the true value Programme the microwave digestion system using a programme with enough temperature or power to digest the sample (check this with the certified reference material) At the end of the digestion period, remove the vessels from the microwave oven, place them in a fume hood and allow the solutions to cool to room temperature Carefully open the vessels (pay attention to the gas pressure that may be present inside the vessels) Quantitatively transfer the liquid contents of each vessel to a 50 ml volumetric flask (the size may be adjusted and will depend on the required limit) Carefully rinse each vessel with grade water into the volumetric flask and make up to volume with water (be sure that the liquid temperature is near room temperature before making the volume up to the mark) Seal each volumetric flask with a stopper and mix thoroughly For all digestions, adjustments may be necessary to achieve total digestion for certain samples and should be based on sound knowledge of the chemistry and appropriate acids for the sample material being analysed 7.5 Determination of metals Determination of the metal amounts in the digestion solutions is performed complying with EN 1233, EN ISO 11885, EN ISO 12846, EN ISO 15586, EN ISO 17294-2, EN ISO 17852 or ISO 8288 Calibration is performed either with calibration solutions in the appropriate matrix or via standard addition In case of excessive concentrations the test solutions shall be diluted with dilution solution (5.7) depending on the analytical system NOTE Use the manufacturer’s instructions 7.6 Reporting of results The results of 7.2 are calculated according to Formula (1) The metal contents in the textile have to be specified in milligram per kilogram (mg/kg) d= where d ß ß ⋅V m ⋅1000 metal content as mass portion, in milligrams per kilogram (mg/kg); mass concentration of metal in the extraction or digestion solution, in micrograms per litre (µg/l); (1) BS EN 16711-1:2015 EN 16711-1:2015 (E) V m volume of solvent, in millilitres (ml); weight of specimen, in grams (g) If a dilution has been applied for testing, the dilution factor has to be taken in account for the determination of the result Formula (2) reads then as follows: d= where f ß ⋅V ⋅ f m ⋅1000 (2) dilution factor Reliability of the method The results of the round robin test are reported in Annex B NOTE “Trueness” and “precision” are terms complying with ISO 5725-1 to describe the accuracy of test methods Test report The test report shall state at least the following particulars: a) name of the laboratory; b) specification of the specimen; c) reference to this European Standard; d) specification of the applied digestion method; e) specification of the applied analytical system; f) amount of each targeted metal in mg/kg; g) details of all procedural steps, that are not defined in this standard or in standards, which are referenced and all work steps, which may be considered as optional, as well as all events, which may have influenced the results BS EN 16711-1:2015 EN 16711-1:2015 (E) Annex A (informative) Laboratory microwave procedure A.1 Cleaning of polytetrafluoroethylene glassware and vessels Perform a cleaning digestion with the digestion vessels made of PTFE prior to the digestion of the specimen with either approximately ml nitric acid (5.1) (see Table A.1) or ml water (5.4) and ml nitric acid (5.1) (see Table A.2) The PTFE vessels should not be exposed to any thermal load higher than 200 °C of inner temperature (approximately 120 °C external temperature), because this will result in a flow of PTFE Use all glassware only after thorough cleaning, maybe after rinsing with water containing nitric acid and subsequent drying Table A.1 — Example of microwave cleaning digestion with ml HNO3 Step Time Power W Temperature °C Ventilation time 1,0 90 15 1,5 250 90 1,8 300 90 Time Power W Temperature °C Ventilation time 5,0 800 180 15 Table A.2 — Example of microwave cleaning digestion with ml HNO3 and ml water Step 4,0 16,0 700 95 180 It is usually enough to soak the vessels for h in a mixture of HNO3/HCl (1% each), after normal cleaning with tap water The above procedure should only be performed if the blank control fails A.2 Sample preparation (digestion) After the expiration of the digestion program (see Tables A.3 and A.4) ventilate the vessels carefully under the lab exhaust, gently add water and fill up to 50 ml in a volumetric flask If a residue is available, filter the digestion solution and subsequently transfer it to the sample vials 10 BS EN 16711-1:2015 EN 16711-1:2015 (E) Table A.3 — Example of microwave digestion for textile samples (10 ml HNO3, ml H2O2/4 ml H2O) Step Time Power W Temperature °C 1,0 60 4,0 300 6,0 400 2,0 600 2,0 6,0 20 95 100 400 120 110 Ventilation time 20 Table A.4 — Example of microwave digestion for textile samples (8 ml HNO3, 2,5 ml H2O2) Step Time Power W Temperature °C 5,0 500 145 200 4,0 5,0 24,0 700 800 85 200 Ventilation time 20 11 BS EN 16711-1:2015 EN 16711-1:2015 (E) Annex B (informative) Procedure characteristics B.1 Trueness complying with ISO 5725-4 Trueness was calculated as systematic measurement error (bias) of the method and in correlation to the mean value, because no reference value of the investigated material is available In a round robin test in 2006 a textile specimen was tested for metal content using different test methods After elimination of outliers (see values marked in grey in Tables B.1 and B.2) a good correlation of the particular laboratory values was verified Table B.1 — Results of statistical evaluation: Determination of contents after total digestion Metal Metal content mg/kg Mean value Standard deviation Variation coefficient x s v mg/kg mg/kg % 1,44 0,264 Laboratory A B C D Sb 10,29 10,10 10,70 Cd 0,17 0,20 0,17 As 0,58 Pb 1,33 Cr 3,89 Co 1,25 Cu 9,10 Ni Hg 0,99 0,17 < 10 1,30 3,00 1,30 9,60 7,10 0,34 0,59 1,24 3,50 1,31 10,00 6,91 0,10 E F G G2 H 11,88 13,95 8,91 11,50 11,10 12,60 0,20 0,25 0,18