Reference test method for release of nickel from all post assemblies which are inserted into pierced parts of the human body and articles intended to come into direct and prolonged contact with the skin

This European Standard specifies a method for simulating the release of nickel from all post assemblies which are inserted into pierced ears and other pierced parts of the human body and articles intended to come into direct and prolonged contact with the skin in order to determine whether such articles are in compliance with No. 27 Annex XVII of Regulation (EC) No 1907/2006 of the European Parliament and of the Council (REACH).
Spectacle frames and sunglasses are excluded from the scope of this European Standard.
NOTE   Spectacle frames and sunglasses are subject to the requirements of EN 16128:2011 which provides an unchanged re-publication of the technical requirements that had previously been specified in EN 1811:1998, but restricted in scope to apply only to spectacle frames and sunglasses.

Referenzprüfverfahren zur Bestimmung der Nickellässigkeit von sämtlichen Stäben, die in durchstochene Körperteile eingeführt werden und Erzeugnissen, die unmittelbar und länger mit der Haut in Berührung kommen

Diese Europäische Norm legt ein Verfahren fest, um die Nickellässigkeit von sämtlichen Stäben, die in durchstochene Ohren und in andere durchstochene Teile des menschlichen Körpers eingeführt werden sowie von Erzeugnissen, die unmittelbar und länger mit der Haut in Berührung kommen, zu bestimmen, um festzustellen, ob diese Erzeugnisse Nr. 27 Anhang XVII der Verordnung (EG) Nr. 1907/2006 des Europäischen Parlaments und des Rates (REACH) entsprechen.
Brillenfassungen und Sonnenbrillen sind von dem Anwendungsbereich dieser Europäischen Norm ausgeschlossen.
ANMERKUNG   Brillenfassungen und Sonnenbrillen unterliegen den Anforderungen von EN 16128:2011, welche eine ungeänderte Neupublikation der technischen Anforderungen enthält, die ursprünglich in EN 1811:1998 enthalten waren, im Anwendungsbereich jedoch eingeschränkt auf Brillenfassungen und Sonnenbrillen ist.

Méthode d'essai de référence relative à la libération du nickel par les assemblages de tiges qui sont introduites dans les parties percées du corps humain et les produits destinés à entrer en contact direct et prolongé avec la peau

La présente Norme européenne spécifie une méthode pour simuler la libération du nickel par tous les assemblages de tiges insérés dans les oreilles percées et d’autres parties percées du corps humain et les articles destinés à venir en contact direct et prolongé avec la peau dans le but de déterminer si ces articles sont conformes au Règlement (CE) n° 1907/2006 du Parlement européen et du Conseil (REACH), en ce qui concerne le n° 27 de l'Annexe XVII.
Les montures de lunettes et les lunettes de soleil sont exclues du domaine d’application de la présente Norme européenne.
NOTE   Les montures de lunettes et les lunettes de soleil sont soumises aux exigences de l’EN 16128:2011 qui est une réédition inchangée des exigences techniques qui ont été préalablement spécifiées dans l’EN 1811:1998, mais dont le domaine d’application est uniquement limité aux montures de lunettes et aux lunettes de soleil.

Primerjalna preskusna metoda za sproščanje niklja iz izdelkov, vstavljenih v prebodene dele človeškega telesa, in izdelkov, ki so v neposrednem in daljšem stiku s kožo

Ta evropski standard določa metodo za simulacijo sproščanja niklja iz vseh izdelkov, vstavljenih v prebodene dele človeškega telesa, in izdelkov, ki so v daljšem neposrednem stiku s kožo, da se določi, ali so ti izdelki v skladu s točko 27 Priloge XVII k Uredbi (ES) št. 1907/2006 Evropskega Parlamenta in Sveta (REACH).
Okvirji očal in sončna očala so izključeni s področja uporabe tega evropskega standarda.
OPOMBA: Okvirji očal in sončna očala morajo ustrezati zahtevam standarda EN 16128:2011, ki vsebuje nespremenjene ponovno objavljene tehnične zahteve, ki so bile prej določene v standardu EN 1811:1998, vendar je bilo njihovo področje uporabe omejeno samo na okvirje očal in sončna očala.

General Information

Status
Published
Publication Date
28-Jul-2015
Current Stage
9092 - Decision on results of review/2YR ENQ - revise - Review Enquiry
Due Date
15-Sep-2016
Completion Date
03-Oct-2017

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Referenzprüfverfahren zur Bestimmung der Nickellässigkeit von sämtlichen Stäben, die in durchstochene Körperteile eingeführt werden und Erzeugnissen, die unmittelbar und länger mit der Haut in Berührung kommenMéthode d'essai de référence relative à la libération du nickel par les assemblages de tiges qui sont introduites dans les parties percées du corps humain et les produits destinés à entrer en contact direct et prolongé avec la peauReference test method for release of nickel from all post assemblies which are inserted into pierced parts of the human body and articles intended to come into direct and prolonged contact with the skin39.060NakitJewelleryICS:Ta slovenski standard je istoveten z:EN 1811:2011+A1:2015SIST EN 1811:2011+A1:2015en,fr,de01-oktober-2015SIST EN 1811:2011+A1:2015SLOVENSKI

STANDARD
SIST EN 1811:2011+A1:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 1811:2011+A1
July 2015 ICS 39.060 Supersedes EN 1811:2011English Version

Reference test method for release of nickel from all post assemblies which are inserted into pierced parts of the human body and articles intended to come into direct and prolonged contact with the skin

Méthode d'essai de référence relative à la libération du nickel par les assemblages de tiges qui sont introduites dans les parties percées du corps humain et les produits destinés à entrer en contact direct et prolongé avec la peau Referenzprüfverfahren zur Bestimmung der Nickellässigkeit von sämtlichen Stäben, die in durchstochene Körperteile eingeführt werden und Erzeugnissen, die unmittelbar und länger mit der Haut in Berührung kommen This European Standard was approved by CEN on 5 February 2011 and includes Corrigendum 1 issued by CEN on 30 May 2012 and Amendment 1 approved by CEN on 20 June 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 1811:2011+A1:2015 ESIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 2 Contents Page European foreword .............................................................................................................................................4 Introduction .........................................................................................................................................................5 1 Scope ......................................................................................................................................................6 2 Normative references ............................................................................................................................6 3 Terms and definitions ...........................................................................................................................6 4 Principle of the procedure ....................................................................................................................7 5 Reagents .................................................................................................................................................7 6 Apparatus ...............................................................................................................................................8 7 Samples ..................................................................................................................................................9 7.1 Sample area ............................................................................................................................................9 7.1.1 Definition of sample area ......................................................................................................................9 7.1.2 Determination of sample area ..............................................................................................................9 7.1.3 Masking of areas other than sample area ...........................................................................................9 7.2 Sample degreasing before testing .......................................................................................................9 7.3 Quality control samples ........................................................................................................................9 8 Procedure ............................................................................................................................................ 10 8.1 Preparation of test solution ............................................................................................................... 10 8.2 Release procedure .............................................................................................................................. 10 8.3 Determination of nickel ...................................................................................................................... 11 8.3.1 General ................................................................................................................................................. 11 8.3.2 Calibration solutions .......................................................................................................................... 11 8.3.3 Detection limit and quantification limit ............................................................................................ 11 8.3.4 Number of test samples ..................................................................................................................... 11 8.3.5 Number of replicate measurements.................................................................................................. 11 8.4 Blank tests ........................................................................................................................................... 11 9 Calculations ......................................................................................................................................... 11 9.1 Nickel release ...................................................................................................................................... 11 9.2 Interpretation of results ..................................................................................................................... 12 9.2.1 General ................................................................................................................................................. 12 9.2.2 Conformity assessment" ................................................................................................................ 12 9.2.3 Uncertainty budget ............................................................................................................................. 13 10 Test report ........................................................................................................................................... 13 Annex A (informative)

!Expanded measurement uncertainty of the test procedure and compliance assessment .................................................................................................................... 14 Annex B (normative)

Requirements for quality control material ................................................................ 16 Annex C (normative)

Requirements for preparation of all post assemblies which are inserted into pierced parts of the human body and articles intended to come into direct and prolonged contact with the skin prior to nickel testing .................................................................................... 18 C.1 General ................................................................................................................................................. 18 C.2 Requirements and principle .............................................................................................................. 18 C.3 Determination of the nickel release test method ............................................................................. 18 C.4 Determination of surfaces coming into direct and prolonged contact with the skin or pierced parts of the body ................................................................................................................... 18 SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 3 C.4.1 Procedures for homogeneous and inhomogeneous articles ......................................................... 18 C.4.1.1 General ................................................................................................................................................. 18 C.4.1.2 Homogeneous articles and all post assemblies .............................................................................. 19 C.4.1.3 Procedure for inhomogeneous articles ............................................................................................ 19 C.4.1.3.1 General .......................................................................................................................................... 19 C.4.1.3.2 Situation 1 ..................................................................................................................................... 19 C.4.1.3.2.1 General .................................................................................................................................... 19 C.4.1.3.2.2 Procedure 1 ............................................................................................................................. 19 C.4.1.3.2.3 Result ....................................................................................................................................... 19 C.4.1.3.3 Situation 2 ..................................................................................................................................... 19 C.4.1.3.3.1 General .................................................................................................................................... 19 C.4.1.3.3.2 Procedure 2 ............................................................................................................................. 19 C.4.1.3.3.3 Result ....................................................................................................................................... 20 C.4.1.3.4 Situation 3 ..................................................................................................................................... 20 C.4.1.3.4.1 General .................................................................................................................................... 20 C.4.1.3.4.2 Procedure 3 ............................................................................................................................. 20 C.4.2 Jewellery products .............................................................................................................................. 20 C.4.2.1 General ................................................................................................................................................. 20 C.4.2.2 Post assemblies and associated parts ............................................................................................. 20 C.4.2.2.1 Parts coming into direct and prolonged contact with the skin and/or pierced parts of the body ................................................................................................................................................ 20 C.4.2.2.2 Decorative attachments of post assemblies ............................................................................. 21 C.4.2.3 Necklaces, bracelets, chains and anklets ......................................................................................... 22 C.4.2.4 Bangles ................................................................................................................................................. 23 C.4.2.5 Rings ..................................................................................................................................................... 23 C.4.2.6 Watches ................................................................................................................................................ 24 C.4.2.6.1 General .......................................................................................................................................... 24 C.4.2.6.2 Parts to be tested ......................................................................................................................... 24 C.4.2.6.3 Parts to be removed from watch before testing ....................................................................... 25 C.4.3 Other articles such as textiles, footwear, garments, leather goods and mobile phones ............ 25 C.5 Methods of determining the surface areas ....................................................................................... 26 C.5.1 Surface area measurements .............................................................................................................. 26 C.5.2 Minimum surface area ......................................................................................................................... 26 C.5.3 Simplification of surface area determination using common shapes of consumer products ............................................................................................................................................... 26 C.6 Testing apparatus prior to nickel release testing ............................................................................ 26 Annex D (informative)

Articles made from composite materials ................................................................. 28 Bibliography ...................................................................................................................................................... 29

SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 4 European foreword This document (EN 1811:2011+A1:2015) has been prepared by Technical Committee CEN/TC 347 “Methods for analysis of allergens”, the secretariat of which is held by !SNV". 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 January 2016, and conflicting national standards shall be withdrawn at the latest by January 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. This document includes Corrigendum 1 issued by CEN on 30 May 2012 and Amendment 1 approved by CEN on 20 June 2015. This document supersedes !EN 1811:2011". The start and finish of text introduced or altered by amendment is indicated in the text by tags !". The modifications of the related CEN Corrigendum have been implemented at the appropriate places in the text and are indicated by the tags ˜ ™. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. This document supports essential requirements of Commission Regulation (EC) No 1907/2006 (REACH) of the European Parliament and the Council. !deleted text" 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. SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 5 Introduction Adverse skin reaction to nickel has been known for many decades. Nickel is the most frequent cause of contact allergy in Europe, and 10 % to 20 % of the patch tested female population and 1 % to 3 % of the patch tested male population are allergic to nickel. Skin absorption of nickel ions, which are released from some nickel-containing materials which are inserted into pierced ears or other pierced parts of the human body or which are in direct and prolonged contact with the skin, causes sensitisation. Further exposure to soluble nickel salts results in allergic contact dermatitis. It is known that sensitisation to nickel requires higher exposure levels than does the elicitation in already sensitised individuals. There is a large variation in the degree of sensitivity to nickel between individuals. This widespread health problem has forced the introduction of a number of measures designed to reduce its prevalence. These measures include the requirements of this standard which provides an in-vitro chemical test that correlates as far as possible with the variable human biological reactions that occur when metallic articles containing nickel are in direct and prolonged contact with the skin and pierced parts of the body. The standard provides a measure of the amount of nickel release from an article immersed for one week in artificial sweat. The standard also describes the preparation of a quality control material intended to assist a laboratory in achieving an acceptable precision. Clinical patch-testing of a small selection of nickel-containing alloys and coatings on nickel-sensitized persons indicates that high and low results achieved with the present analytical method correspond closely with patch-test reactivity. Moreover, a nickel migration limit of 0,5 µg/cm2/week for articles intended to come into direct and prolonged contact with the skin and a nickel migration limit of less than 0,2 µg/cm2/week for all post piercing assemblies inserted into pierced ears and other pierced parts of the human body has been set in Commission Regulation (EC) No 1907/2006 of the European Parliament and the Council (in the current version). SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 6 1 Scope This European Standard specifies a method for simulating the release of nickel from all post assemblies which are inserted into pierced ears and other pierced parts of the human body and articles intended to come into direct and prolonged contact with the skin in order to determine whether such articles are in compliance with No. 27 Annex XVII of Regulation (EC) No 1907/2006 of the European Parliament and of the Council (REACH). Spectacle frames and sunglasses are excluded from the scope of this European Standard. NOTE Spectacle frames and sunglasses are subject to the requirements of EN 16128:2011 which provides an unchanged re-publication of the technical requirements that had previously been specified in EN 1811:1998, but restricted in scope to apply only to spectacle frames and sunglasses. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12472, Method for the simulation of wear and corrosion for the detection of nickel release from coated items EN ISO 3696:1995, Water for analytical laboratory use — Specification and test methods (ISO 3696:1987) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 barrette component used to secure the watchstrap to the case 3.2 homogeneous consisting of a single material having a common surface finish 3.3 post assembly ear stud or body piercing article 3.4 release solution solution resulting from the release procedure according to 8.2 3.5 representative best estimate for the effective release rate of all surfaces which are in direct and prolonged contact with the skin or pierced parts of the body under normal conditions of use NOTE This property is defined with respect to the release rate. SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 7 3.6 sample area a surface(s) that is(are) immersed in the test solution and not covered with a masking agent 3.7 test solution solution as prepared according to 8.1 3.8 watch crown winder used to alter the time/date 4 Principle of the procedure The article to be tested for nickel release is placed in an artificial sweat test solution for one week. The concentration of dissolved nickel in the solution is determined by an appropriate analytical method, for example inductively-coupled plasma spectrometry. The nickel release is expressed in micrograms per square centimetre per week (µg/cm2/week). NOTE Indicative information on the extent of nickel release can be obtained by performing one of the tests specified in CR 12471. 5 Reagents Except where indicated, all reagents shall be of recognized pro analysis, p.a., grade or better and shall be free of nickel. 5.1 Deionised water according to EN ISO 3696:1995, grade 2. 5.2 Sodium chloride. 5.3 DL-lactic acid 5.4 Urea. 5.5 Sodium hydroxide in solid tablets, min 98 % pure dehydrate. 5.6 Preparation of 1 M sodium hydroxide solution. Weigh 4 g ± 0,01 g of sodium hydroxide (5.5) and transfer into a 100 ml beaker and add 50 ml of deionised water (5.1). Stir and cool to room temperature. Transfer the solution to a 100 ml volumetric flask and make up to volume with deionised water (5.1). 5.7 Preparation of 0,1M sodium hydroxide solution Add 25 ml of 1 M sodium hydroxide (5.6) in a 250 ml volumetric flask and make up to volume with deionised water (5.1). 5.8 ˜Hydrochloric acid, ™ 5.9 ˜Preparation of 0,1 M hydrochloric acid solution Transfer 1 ml of hydrochloric acid (5.8) into a 100 ml volumetric flask and make up to volume with deionised water (5.1).™ SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 8 5.10 Nitric acid 5.11 Dilute nitric acid, approximately 5 % (m/m). Transfer 30 ml of nitric acid (5.10) into a 500-ml beaker containing about 350 ml of deionised water (5.1). Stir and cool to room temperature. Transfer the solution to a 500-ml volumetric flask and make up to volume with deionised water. 5.12 Degreasing solution. Dissolve 5 g of an anionic surface-active agent such as sodium dodecylbenzene sulfate or sodium alkylaryl sulfate in 1 000 ml deionised water (5.1). An appropriately diluted, neutral, commercially available detergent may be used. 5.13 Wax or lacquer (suitable for electroplating purposes) capable of protecting a surface from nickel release. The wax or lacquer shall be shown to prevent nickel release from a nickel-releasing surface when one or more coats of the wax or lacquer are applied in the same manner as on a test sample and shall not affect the nickel content of the release solution. The suitability of the wax / lacquer shall be tested. NOTE Information on sourcing of a suitable wax or lacquer is available from the CEN/CENELEC Management Centre. 6 Apparatus 6.1 A pH-meter, accurate to ± 0,05 pH. 6.2 An analytical instrument capable of detecting a concentration of 0,01 mg nickel per litre in the final release solution. It is recommended that either an inductively-coupled plasma spectrometer (ICP-OES, optical emission, or ICP-MS, mass spectrometer) or an electro thermal excitation atomic absorption spectrometer (GFAAS) is used. 6.3 Thermostatically controlled water-bath or oven with or without cooling option, capable of maintaining a temperature of (30 ± 2) °C. 6.4 A vessel with lid, both composed of a non-metallic, nickel-free and nitric-acid-resistant material, such as glass and/or polypropylene and/or polytetrafluoroethylene and/or polystyrene. The sample shall be suspended in the liquid by a holder made from the same materials as listed above, so as to avoid contact of the sample area (7.1.1) with the walls and base of the vessel. The size and shape of vessel and holder shall be chosen so as to minimize the volume of test solution required to completely cover the article to be tested. In order to remove any trace of nickel, the vessel and holder shall be pre-treated by being stored in a solution of dilute nitric acid (5.11) for at least 4 h. After acid cleaning, rinse the vessel and holder with deionised water and dry. 6.5 Device for length measuring, for example a digital calliper with a minimum resolution of 50 µm or a micrometer with a minimum resolution of 5 µm. SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 9 7 Samples 7.1 Sample area 7.1.1 Definition of sample area Only the surface(s) that come(s) into direct and prolonged contact with the skin and/or that have contact with the pierced parts of the body shall be tested (sample area). In case of articles which are made of uniform material(s), consideration should be given to testing the whole surface (whether or not it is all in direct and prolonged contact with the skin or with pierced parts of the body) since errors can be introduced by the masking process (see 7.1.3). The test laboratory shall refer to C.4 in order to determine which surfaces are to be tested. 7.1.2 Determination of sample area Determination of the sample area (a) in square centimetres is achieved by marking the contour of the sample area assuming that the article is worn or used as intended (refer to Annex C) and measuring it by an appropriate measuring device (6.5). In order to achieve the required degree of analytical sensitivity, a minimum sample area of 0,2 cm2 shall be tested. If necessary, identical articles may be tested together to obtain this minimum area. The closer the nickel release is to the limits laid down in the regulation, or the smaller the sample area is, the more precise the surface measurement needs to be. 7.1.3 Masking of areas other than sample area In order to prevent release of nickel from areas other than the sample area, such areas shall be removed or protected from the test solution. This can be achieved after degreasing (refer to 7.2) by the application of one or more coatings of a wax or lacquer (5.13) which has been shown to protect from nickel release. The test laboratory shall refer to C.4 in order to determine which surfaces are to be tested. 7.2 Sample degreasing before testing Gently swirl the sample for 2 min in degreasing solution (5.12) at room temperature. Rinse thoroughly with deionised water and dry using an absorbing cloth. After degreasing, articles shall be handled with plastic forceps or clean protective gloves. NOTE This cleaning stage is intended to remove extraneous grease and skin secretions due to handling, but not any protective coatings. 7.3 Quality control samples As a quality control check, the nickel release from a quality control sample shall be determined (refer to Annex B) on a frequent basis. The quality control sample shall be degreased in the same way as the sample according to 7.2 and shall be used only once. SIST EN 1811:2011+A1:2015

EN 1811:2011+A1:2015 (E) 10 8 Procedure 8.1 Preparation of test solution The test solution consists of deionised water (5.1) containing: — 0,5 % (m/m) sodium chloride (5.2); — 0,1 % (m/m) lactic acid (5.3); — 0,1 % (m/m) urea (5.4); and — 1 M (5.6) and 0,1 M (5.7) sodium hydroxide solution. The test solution shall be prepared as follows: Pour 900 ml of freshly prepared deionised water (5.1) to a 1 000 ml beaker. Add 1,00 ± 0,01 g of urea (5.4), 5,00 ± 0,05 g of sodium chloride (5.2) and 1,00 ± 0,01 g of lactic acid (5.3), and stir until dissolved. Calibrate a pH meter in accordance with the manufacturer’s instructions using freshly prepared buffer solutions. Immerse the pH electrode into the test solution and measure the pH. Slowly and gently, add drop by drop a volume of 1 M sodium hydroxide (5.6) until a pH of 5,5 ± 0,05 is reached and subsequently with continuous stirring, add slowly and gently drop by drop a volume of 0,1 M sodium hydroxide (5.7) until a pH 6,5 ± 0,05 is reached and remains stable. Measure the pH after 10 min from the last addition of 0,1 M sodium hydroxide to ensure that the pH is in the range 6,5 ± 0,05. Transfer the solution to a 1 000 ml volumetric flask and make up to volume with deionised water. Before use, ensure that the pH of the test solution is in the range of pH 6,5 ± 0,05. If it is necessary to reduce the pH of the solution to 6,5 ± 0,05 before testing, this shall be done by adding slowly and gently with continuous stirring drop by drop a volume of 0,1 M hydrochloric acid (5.9). The test solution shall be prepared daily. 8.2 Release procedure NOTE In the following text the term "test solution" represents the solution as prepared according to 8.1, the "release solution" is the solution resulting

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