1、BRITISH STANDARD Surface active agents - Determination of water content - Karl Fischer method The European Standard EN 13267:2001 has the status of a British Standard ICs 71.100.40 BS EN 13267:2001 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS EN 13267:2001 Amd. No. Natio
2、nal foreword Date Comments This British Standard is the official English language version of EN 13267:2001. It supersedes BS 6829-1.5:1990 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee CIU34, Methods of test for surface active agents, which has the
3、responsibility to: - - aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. - A list
4、 of organizations represented on this committee can be obtained on request to its secretary. Additional information Some textual errors were discovered when the English language version of EN 13267:2001 was adopted as the national standard. Some of the chemical names are not consistently presented a
5、nd do not conform to IUPAC recommendations. These textual errors have been reported to CEN in a proposal to amend the text of the European Standard. Cross-references The British Standards which implement international or European publications may be found in the BSI Standards Catalogue under the sec
6、tion entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application
7、. Compliance with a British Standard does not of itself confer immunity from legal obligations. This British Standard, having been prepared under the direction of the Sector Committee for Materials and Chemicals, was published under the authority of the Standards Committee and comes into effect on 1
8、5 June 2001 8 BSI 06-2001 Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 11 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication ISBN O 580 37
9、405 X EUROPEAN STANDARD EN 13267 NORME EUROPENNE EUROPECHE NORM March 2001 ICs 71.100.40 English version Surface active agents - Determination of water content - Karl Fischer method Agents de surface - Dtermination de la teneur en eau - Mthode de Karl Fischer Grenzfichenakiive Stoffe - Bestimmung de
10、s Wassergehaltes - Verfahren nach Karl Fischer This European Standard was approved by CEN on 4 February 2001. CEN members are bound to comply with the CENICENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alter
11、ation. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the 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 translat
12、ion under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy
13、, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMITE EUROPEEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels O 2001 CEN All rights of exploitation in any form
14、and by any means reserved worldwide for CEN national Members. Ref. No. EN 13267:2001 E Page 2 EN 13267:2001 Contents Foreword . 3 1 Scope . 4 2 Normative references . 4 3 Terms and definitions . 4 4 Principle . 4 5 Reagents 4 6 Apparatus 5 7 Sampling 5 8 Procedure 5 o 9 Precision 8 1 O Test report .
15、 8 Annex A (informative) Preparation of Karl Fischer reagent containing pyridine 9 Annex B (informative) Interlaboratory test results . 10 Bibliography . 11 O BSI 06-2001 Page 3 EN 13267:2001 Foreword This European Standard has been prepared by Technical Committee CEN/TC 276, Surface active agents,
16、the Secretariat of which is held by AFNOR. 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 September 2001, and conflicting national standards shall be withdrawn at the latest by September 2001. Th
17、e annexes A and B are informative. According to the CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Lu
18、xembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. a O BSI 06-2001 Page 4 EN 13267:2001 1 Scope This European Standard specifies the Karl Fischer method using electrometric end point detection for the determination of the water content of surface active agent
19、s. O The method is applicable to products in form of powders, pastes and solutions. The following substances interfere with Karl Fischer reagent: alkali metal silicates, carbonates; hydroxides and borates; oxidizing agents, ketones, aldehydes; strong mineral acids and strong bases. Samples that cont
20、ain any of these substances cannot be measured directly by this present method; in those situations the solvent system andior the Karl Fischer reagent have to be modified, but these modifications are out of the scope of this European Standard. 2 Normative references This European Standard incorporat
21、es by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European
22、Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). O EN IS0 3696, Water for analytical laboratory use - Specification and test methods (IS0 3696:1987). IS0 607, Surface active agents
23、 and detergents - Methods of sample division. 3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 water content amount of water, water of cristallization, absorbed water or occluded water, expressed as a percent by mass 4 Principle The w
24、ater present in the test portion is reacted with a solution of iodine and sulfur dioxide in an appropriate mixture (Karl Fischer reagent), previously standardized by titration with an exactly known mass of water. The water content is calculated from the amount of reagent used as percent by mass. 5 R
25、eagents During the analysis, use only reagents of recognized analytical grade and water complying with grade 1 as defined in EN IS0 3696. 5.1 Solvent, methanol, 2-methoxyethanol or propan-1-01 NOTE The water content should be as low as possible in order to save Karl Fischer reagent. 5.2 prepared. Ka
26、rl Fischer reagent, having a water equivalent of approximately 5 mgiml, preferably commercially NOTE A non-pyridine containing reagent is preferred mainly for safety reasons. A commercially available reagent containing iodine, sulfur dioxide and an amine dissolved in 2-methoxyethanol is suitable. A
27、pyridine reagent can be used if it has been shown to be suitable. This should be included in the test report. A reagent containing pyridine can be prepared as specified in annex A. O O BCI 06-2001 Page 5 EN 13267:2001 6 Apparatus Ordinary laboratory apparatus and the following: 6.1 Karl Fischer appa
28、ratus, fully automatic or semi-automatic, consisting of: - titrator with double platinum electrode; - piston burette, with a resolution less or equal to 0,Ol ml; capable of controlling the dosage rate, the time of delay, the stop time and the drift; - drying tubes containing molecular sieve pore siz
29、e 0,3 nm (silica gel is not sufficient as a protective agent); - magnetic stirrer. 6.2 Gas tight syringe, capacity 1 O0 pl (optional). 6.3 Clinical glass syringe, with movable needle. 6.4 Analytical balance, accurate to 0,l mg. 7 Sampling The laboratory sample shall have been prepared and stored in
30、accordance with IS0 607. 8 Procedure 8.1 General Atmospheric moisture is the biggest source of interference in the Karl Fischer titration. Take care to dry the apparatus thoroughly and to handle the test portions and solvents speedily to prevent access of moisture. Operate the Karl Fischer apparatus
31、 in accordance with the manufacturers instructions. 8.2 Determination of the water eauivalent of the Karl Fischer reagent 8.2.1 General O Determine the water equivalent on each new container of reagent and then at least weekly. NOTE accuracy govern the frequency of determination of the water equival
32、ent. The water equivalent can change during storage. The type of apparatus used and the desired analytical 8.2.2 Preparation Clean the electrode with tissue paper moistened with a suitable solvent, e.g. acetone. Wipe-off the acetone. Install a clean and dry titration vessel; introduce a clean and dr
33、y magnetic stirring bar. Transfer enough volume of solvent (5.1) as to immerse the electrode platinum tips by 2 mm to 3 mm. Titrate with the Karl Fischer reagent (5.2) in order to neutralize any trace of moisture, avoiding any excess of reagent. NOTE If an automatic apparatus is used, the following
34、instrumental conditions are recommended: maximum dosage rate 15 mllmin; O BSI 06-2001 Page 6 EN 13267:2001 - minimum increment 9 Pl; - initial volume O ml; - stop time 20 s; - initial delay 10 s; - drift control automatically. 8.2.3 Determination Introduce a precise amount of water as to consume a v
35、olume of Karl Fischer reagent corresponding to more than 80 % of the capacity of the piston burette. The water shall be introduced using the syringe (6.2); record the exact amount of water (m,) introduced by weighing the syringe to the nearest 0,l mg before and after introducing the water. NOTE that
36、 its accuracy is at least equal to that of the analytical balance (6.4). A digital syringe can also be used to control the amount of water added as long as there is enough evidence Titrate with Karl Fischer reagent (5.2) until the electrometric end point has been reached (see 8.2.2 note). 8.2.4 Calc
37、ulation The water equivalent E, expressed as milligrams of water per millilitre, is given by the equation (1): mw Ew =- VI where: mW is the mass, in milligrams, of water introduced; VI is the volume, in millilitres, of Karl Fischer reagent consumed at the titration. Repeat the introduction of water
38、and titration two more times. Calculate the mean of these E, values for which standard deviation shall be less than 0,05 mg/ml. Retain this mean as the water equivalent Ew 8.3 Determination of the water content 8.3.1 General Depending on the characteristics of the laboratory sample, one of the follo
39、wing two methods shall be chosen, namely the general method (8.3.2) or the dissolution method (8.3.3). The general method is suitable for samples which are homogeneous and easy to dispense into the titration vessel. The dissolution method shall be used for samples for which homogeneity is questionab
40、le andlor that are difficult to dispense into the titration vessel. O BSI 06-2001 Page 7 EN 13267:2001 8.3.2 General method 8.3.2.1 Preparation Proceed as described in 8.2.2. If the titration vessel contains too much solvent from previous determinations, remove some of it. Also be aware of solid dep
41、osits on platinum tips of the electrode, which can cause important errors; remove them with a suitable solvent and tissue paper. 8.3.2.2 Determination Fill into the titration vessel a test portion (m) of the material whose percentage of water is to be determined. Check the amount to the nearest 0,l
42、mg by difference of masses. Chose the amount as to consume a volume of Karl Fischer reagent corresponding to more than 50 % of the capacity of the piston burette. Titrate with Karl Fischer reagent (5.2) until the electrometric end point has been reached (see 8.2.2 note). 8.3.2.3 Calculation The wate
43、r content WHzoi expressed as percent by mass, in the sample is given by the equation (2): e where: m is the mass, in grams, of the test portion taken in 8.3.2.2; E, is the water equivalent of Karl Fischer reagent according to 8.2.4; VZ is the volume, in millilitres, of Karl Fischer reagent consumed
44、in 8.3.2.2. 8.3.3 Dissolution method 8.3.3.1 Determination Weigh a suitable amount of laboratory sample (mi) into a dry flask. Add a suitable amount of any organic solvent (mz) that does not interfere with Karl Fischer reagent (5.2). The amounts of sample and solvent shall be chosen as to use the ma
45、ximum possible amount of sample and the minimum proportion of the solvent, in order to obtain a manageable blend and not compromise the representativity of the sample uptake. Record the mass to the nearest 0,001 g. Stopper the flask and shake until a homogeneous blend is obtained. If at this stage i
46、nsoluble salts settle in the bottom of the flask, the method has to be abandoned, because: a) part of the water might have been removed by the insoluble salts as crystallization water; and b) a rigorous procedure would have to involve the correct determination of the mass of the insoluble salts. Det
47、ermine the water content of both the solvent and the blend, following the procedure given in 8.3.2. O BSI 06-2001 Page 8 EN 13267:2001 8.3.3.2 Calculation The water content WHz0, expressed in percent by mass, in the sample is given by the equation (3): vb (m, +mz)-m, xw2 WH*O = ml (3) where: ml is t
48、he mass, in grams, of sample taken in 8.3.3.1; m2 is the mass, in grams, of solvent used in 8.3.3.1 ; wb is the water content in the blend according to 8.3.3.1, in percent (mlm); w2 is the water content in the solvent according to 8.3.3.1, in percent (mlm). 9 Precision 9.1 Repeatability limit The ab
49、solute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will not exceed the repeatability limit, I, in more than 5 % of cases. According to the ring test results given in annex B, the repeatability limit, I, shall be: - less than or equal to 0,005 g/l O0 g for a water content of approximately 0,07 % (m/m); or - less than or equal to 0,3 g/l O0 g for a water content of approximately 12,2 % (m/m); or - less than or equa
