DIN EN 15692-2009 Ethanol as a blending component for petrol - Determination of water content - Karl Fischer potentiometric titration method English version of DIN EN 15692 2009-08.pdf

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1、August 2009DEUTSCHE NORM English price group 8No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 75.160.20!$Y9%“1542202ww

2、w.din.deDDIN EN 15692Ethanol as a blending component for petrol Determination of water content Karl Fischer potentiometric titration methodEnglish version of DIN EN 15692:2009-08Ethanol zur Verwendung als Blendkomponente in Ottokraftstoff Bestimmung des Wassergehaltes Potentiometrische Titration nac

3、h Karl FischerEnglische Fassung DIN EN 15692:2009-08www.beuth.deDocument comprises 11 pagesDIN EN 15692:2009-08 National foreword This standard has been prepared by Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”

4、 (Secretariat: NEN, Netherlands). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee NA 062-06-81 AA Gasfrmige und flssige Kraft- und Brennstoffe, Schmierstoffe und verwandte Produkte mit mineral

5、lstmmiger, synthetischer oder biologischer Herkunft of the Fachausschuss Minerall- und Brennstoffnormung (FAM). The International Standards referred to in this document have been published as the corresponding DIN EN or DIN EN ISO Standards, except for that below, which corresponds as follows: EN IS

6、O 3696 DIN ISO 3696 National Annex NA (informative) Bibliography DIN ISO 3696, Water for analytical laboratory use Specification and test methods 2 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15692 April 2009 ICS 75.160.20 English Version Ethanol as a blending component for petrol Determina

7、tion of water content Karl Fischer potentiometric titration method Ethanol comme base de mlange lessence Dtermination de la teneur en eau Mthode de titrage potentiomtrique Karl Fischer Ethanol zu Verwendung als Blendkomponente in Ottokraftstoff Bestimmung des Wassergehaltes Potentiometrische Titrati

8、on nach Karl Fischer This European Standard was approved by CEN on 19 March 2009. 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

9、bibliographical references concerning such national standards may be obtained on application to the CEN 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 responsibi

10、lity of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland,

11、Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marni

12、x 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15692:2009: EEN 15692:2009 (E) 2 Contents PageForeword 3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle 4 5 Reagents and material

13、s 4 6 Apparatus .5 7 Sampling and sample handling 5 8 Procedure .6 8.1 Standardization of the Karl Fischer reagent .6 8.2 Analysis 6 9 Calculation 7 10 Expression of results 7 11 Precision .7 11.1 General 7 11.2 Repeatability, r .8 11.3 Reproducibility, R 8 12 Test report 8 Bibliography 9 DIN EN 156

14、92:2009-08 EN 15692:2009 (E) 3 Foreword This document (EN 15692:2009) has been prepared by Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”, the secretariat of which is held by NEN. This European Standard shall be

15、 given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2009, and conflicting national standards shall be withdrawn at the latest by October 2009. Attention is drawn to the possibility that some of the elements of this document

16、 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 was prepared by CEN/TC 19s Ethanol Task Force under its Working Group 21 and is based on ISO 760 1. It is developed as an alternative to EN 15489 2, del

17、ivering a method more widely used in the alcohol and beverage industry environment. 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, Cyprus, Czech Republic, De

18、nmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DIN EN 15692:2009-08 EN 15692:2009 (E) 4 1 Scope This Europ

19、ean standard specifies a method for the direct determination of water in ethanol to be used in gasoline blends. It is applicable in the range 0,05 % (m/m) to 0,54 % (m/m). NOTE For the purposes of this European Standard, the term “% (m/m)” is used to represent the mass fraction. WARNING Use of this

20、standard may involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability

21、 of regulatory limitations prior to use. 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 amendm

22、ents) applies. EN ISO 3170, Petroleum liquids Manual sampling (ISO 3170:2004) EN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696:1987) 3 Terms and definitions For the purposes of this European Standard, the following term and definition applies. 3.1 water conte

23、nt content of water determined by potentiometric Karl Fischer procedure as given in this document 4 Principle A weighed test portion is injected into the titration vessel of a potentiometric Karl Fischer apparatus. The water present is titrated to a potentiometric end point using Karl Fischer reagen

24、t. Iodine (I2), with presence of anhydride sulfur (SO2), of methanol (CH3OH) and of an appropriate nitrogen base (RN), is introduced for the Karl Fischer reaction. Based on the stoichiometry of the reaction, one mole of iodine reacts with one mole of water. The reaction can be expressed as follows:

25、CH3OH + SO2 + RN RNHSO3CH3 H2O +I2 + RNHSO3CH3 + 2RN RNHSO4CH3+2RNHI 5 Reagents and materials Use only chemicals and reagents of recognized analytical grade. 5.1 Karl Fischer reagent, pyridine-free Karl Fischer reagent, containing iodine, sulfur dioxide and a odourless amine and with a nominal water

26、 equivalent content of either 2 mg or 5 mg water per ml equivalent. The Karl Fisher reagent shall be standardized daily before use (see 8.1). DIN EN 15692:2009-08 EN 15692:2009 (E) 5 5.2 Titration solvent methanol, anhydrous methanol with a water content of less than 0,05 % (m/m). 5.3 Water, complyi

27、ng with grade 3 of EN ISO 3696. 6 Apparatus 6.1 Karl Fischer titrator, using a potentiometric end-point. NOTE Karl Fischer titrators are commercially available and some of them automatically stop the titration at the end-point. Instructions for operation of these devices are provided by the manufact

28、urer and are not described here. The method described in this document is using a titrator with a 5 ml burette. 6.2 Electrode platinum/platinum 6.3 Syringes NOTE Needles with bores between 0,5 mm and 0,8 mm have been found suitable, such as syringe of single use with Luer connection, 5 ml or 10 ml c

29、apacity. 6.3.1 Syringe, of approximately 10 l capacity, fitted with a needle of sufficient length to enable the tip to reach under the surface of the liquid in the titration vessel when inserted through the inlet-port septum. 6.3.2 Syringe, of approximately 10 ml capacity, fitted with a needle of su

30、fficient length to enable the tip to reach under the surface of the liquid in the titration vessel when inserted through the inlet-port septum. 6.4 Analytical balance, capable of weighing with an accuracy of 0,1 mg. 6.5 Automatic burette, of 5 ml or 10 ml capacity, protected from humidity by the use

31、 of a molecular sieve (6.6) at the top. NOTE Although it is recommended that an automatic burette connected to a reservoir containing the Karl Fischer reagent is used, a burette, of approximately 5 ml capacity, fitted with a guard tube filled with molecular sieve (6.6) to prevent the ingress of mois

32、ture, may also be used. 6.6 Molecular sieve, granulometry proximally 1,6 mm to 2,5 mm, pore size close to 1 nm. If required to be dried it shall be placed in an oven at proximally 140 C for about 8 hours, then cooled in a dessicator to room temperature. 7 Sampling and sample handling 7.1 Samples sha

33、ll be taken as described in EN ISO 3170. 7.2 Take care to minimise the uptake of atmospheric moisture during sampling and sample handling. 7.3 Samples shall be shaken before used. 7.4 Samples shall be stored capped at room temperature in a dry place to avoid modification of water content. NOTE The u

34、se of a glass bottle that can be sealed with a septum has been found suitable for sampling and sample handling. A test portion of the sample can be taken through the septum with a syringe fitted with a needle. DIN EN 15692:2009-08 EN 15692:2009 (E) 6 8 Procedure 8.1 Standardization of the Karl Fisch

35、er reagent 8.1.1 Add sufficient of the titration solvent (5.2) to the clean, dry titration vessel (6.1) to cover the electrodes. Seal all openings to the vessel, start the magnetic stirrer and adjust for smooth stirring action. Turn on the indication circuit and add KF reagent (5.1) from the burette

36、 until the end point is reached. Swirl the titration vessel to dry inside walls. Add more KF reagent if needed until a steady end point is reached and maintained for at least 15 s. Repeat these swirling and titration steps until the vessels walls are dry. 8.1.2 Fill a 10 l syringe (6.3.1) with pure

37、water, taking care to eliminate air bubbles. Wipe the needle with a tissue to remove any residual water from its surface. Using the balance (6.4) weigh the syringe and the water and record the mass in mg (W). 8.1.3 Insert the needle of the syringe into the titration vessel via the inlet port septum.

38、 Ensure that the tip of the needle is below the surface of the titration solvent. Add the contents of the syringe to the titration solvent in the vessel which has been adjusted to its end point. Titrate the water with KF reagent until a steady end point is reached and maintained at least 15 s. After

39、 adding water, do not shake the vessel. 8.1.4 Record, to the nearest 0,01 ml, the volume of titrant needed to reach the end point (T). Reweigh the empty syringe and record the mass in mg. 8.1.5 To check the conformance of the KF reagent, calculate the water equivalence of KF reagent, use the followi

40、ng equation: F = W / T (1) where, F is the water equivalence of the KF reagent, expressed in mg/ml; W is the mass of water added in mg (see 8.1.2); T is the volume of titrant needed to reach the end point, expressed in ml (see 8.1.4). 8.1.6 Repeat the procedure specified in 8.1.1 to 8.1.5 to give a

41、duplicate value. 8.1.7 If the variation between the two titrations is greater than 2 % relative, discard the contents of the titration vessel. Introduce a further portion of appropriate titration solvent into the vessel and repeat the standardization procedure starting from 8.1.1. 8.1.8 If the titra

42、tions for two further portions of water still vary by more than 2 % relative, it is likely that either the Karl Fischer reagent and/or the titration solvent have aged. Replace these with fresh reagents and repeat the procedure starting from 8.1.1 8.1.9 Record the mean water equivalence value. 8.2 An

43、alysis 8.2.1 Add fresh titration solvent (5.2) to the clean, dry titration vessel (6.1) and titrate the solvent to the end point conditions as described in 8.1.1. DIN EN 15692:2009-08 EN 15692:2009 (E) 7 8.2.2 Dry the inside of a 10 ml syringe (6.3.2) by drawing the titration solvent up into the syr

44、inge and discharging back into the titration vessel. If the vessel contents become wet, add KF reagent (5.1) until the end point is maintained for at least 15 s without further addition of titrant. Repeat this drying procedure until no further addition of KF reagent is necessary to maintain the end

45、point state for at least 15 s (alternatively, oven-dried syringes, cooled in a dessicator may be used). 8.2.3 Immediately after mixing, use the dry syringe to withdraw at least three portions of the sample and discard as waste. 8.2.4 Immediately withdraw a 4 ml to 8 ml (depending on the water conten

46、t) test portion of the sample, clean the needle with a paper tissue and weight the syringe and contents to the nearest 0,1 mg. Insert the syringe into the titration vessel via the inlet port septum, such that the needle is above the surface of the solvent, and discharge its contents. Withdraw the sy

47、ringe, reseal the vessel, reweigh to the nearest 0,1 mg and record the mass m1of the sample test portion taken. 8.2.5 Titrate to the end point state, which shall be stable for at least 15 s. Do not shake the cell after addition of the sample. 8.2.6 Record, to the nearest 0,01 ml, the volume of titra

48、nt needed to reach the end point (V) and the water equivalence of KF reagent (m2). NOTE The solvent should be changed when the test portion content exceeds 2 g of sample per 15 ml of solvent or when 4 ml of titrant per 15 ml of solvent has been added to the titration vessel. 9 Calculation Calculate

49、the water content of the sample, Cs, expressed in % (m/m), using the following equation: 1012s=mVmC (2) where m1is the mass of the test portion, expressed in grams (g) (see 8.2.4); m2 is the mass of water in 1 ml of Karl Fischer reagent, expressed in mg/ml (see 8.2.6); V is the volume of titrant required to reach the end point titration, expressed in ml (see 8.2.6). 10 Expression of results Report the water content of the sample to the nearest 0,01 % (m/m). 11 Precision 11.1 General The precision given was derived from sta