1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58p-Toluensulfonyl isocyanate (TSI) method and potentiometric titration with tetrabutylammonium hydro
2、xideThe European Standard EN 15168:2006 has the status of a British StandardICS 71.100.40Surface active agents Determination of hydroxyl value BRITISH STANDARDBS EN 15168:2006BS EN 15168:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29
3、December 2006 BSI 2006ISBN 0 580 49887 5Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. I
4、t is the UK implementation of EN 15168:2006.The UK participation in its preparation was entrusted to Technical Committee CII/34, Methods of test for surface active agents.A list of organizations represented on CII/34 can be obtained on request to its secretary.This publication does not purport to in
5、clude all the necessary provisions of a EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15168November 2006ICS 71.100.40English VersionSurface active agents - Determination of hydroxyl value - p-Toluensulfonyl isocyanate (TSI) method and potentiometrictitration with tetrabutylammonium hydroxideAgen
6、ts de surface - Dtermination de lindice dhydroxyle -Mthode la p-tolunesulfonylisocyanate (TSI) et titragepotentiomtrique avec lhydroxyde de ttrabutylammoniumGrenzflchenaktive Stoffe - Bestimmung der Hydroxylzahl -p-Toluolsulfonylisocyanat-(TSI-) Verfahren undpotentiometrische Titration mitTetrabutyl
7、ammoniumhydroxidThis European Standard was approved by CEN on 6 October 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and biblio
8、graphical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a C
9、EN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
10、Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006
11、 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15168:2006: EEN 15168:2006 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle4 5 Reagents.5 6 Apparatus .5 7 Sampling.6 8 Procedure
12、 .6 9 Calculation and expression of results.8 10 Precision.8 11 Test report 8 Annex A (informative) Interferences9 Annex B (informative) Titration apparatus settings.10 Annex C (informative) Example for a typical potentiometric titration curve.11 Annex D (informative) Statistical and other data deri
13、ved from the results of inter-laboratory tests .12 Bibliography 13 EN 15168:2006 (E) 3 Foreword This document (EN 15168:2006) has been prepared by Technical Committee CEN/TC 276 “Surface active agents”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a
14、national standard, either by publication of an identical text or by endorsement, at the latest by May 2007, and conflicting national standards shall be withdrawn at the latest by May 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countr
15、ies are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden,
16、Switzerland and United Kingdom. EN 15168:2006 (E) 4 1 Scope This European Standard specifies a method for the determination of hydroxyl value of aliphatic and cyclic hydroxyl compounds with hydroxyl groups attached to primary and secondary carbon atoms. This European Standard is applicable to polyac
17、etals, temperature sensitive materials, high solids polymer polyols and rigid polyols and phenols. This European Standard is not suitable for determination of hydroxyl groups attached to tertiary carbon atoms. NOTE This method is currently recommended for neutral refined products. However for produc
18、ts that contain an excess of acidic species a validation should be carried out to show that the acidic species either does not interfere or that the acidic species interference has been obviated. 2 Normative references The following referenced documents are indispensable for the application of this
19、document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696:1987) ISO 607, Surface active agents and
20、 detergents Methods of sample division 3 Terms and definitions For the purposes of this document, the following term and definition applies. 3.1 hydroxyl value, OHV number of milligrams of potassium hydroxide corresponding to the hydroxyl groups in 1 g of material 4 Principle A known mass of test sa
21、mple is reacted with an excess of p-toluenesulfonyl isocyanate to form an acidic carbamate. Water is added to convert un-reacted isocyanate to sulfonamide followed by direct potentiometric titration of the acidic carbamate with tetra-n-butyl ammonium hydroxide in non-aqueous medium. The reactions oc
22、curring are as follows: a) formation of acidic carbamate; CH3SO2-NCO + R-OH CH3SO2-NHCOOR b) hydrolysis of the excess of isocyanate; CH3SO2-NCO + H2O CH3SO2NH2+ CO2EN 15168:2006 (E) 5 c) titration of the acidic carbamate formed. CH3SO2-NH COOR + OH- CH3SO2-N- COOR + H2O 5 Reagents During the analysi
23、s, unless otherwise specified, use only reagents of recognized analytical grade that have been checked in advance as to not interfere with the analytical results. WARNING Acetonitrile, p-toluenesulfonyl isocyanate and tetrabutylammonium hydroxide being hazardous chemicals: conduct all the operations
24、 under a well-ventilated fume hood. 5.1 Water complying with grade 3 as defined in EN ISO 3696. 5.2 Acetonitrile, with water content 0,01 % (m/m) (CAS number : 75-05-8). 5.3 Toluene, minimum purity 99 % (m/m) (CAS number : 108-88-3). 5.4 Tetrahydrofurane (THF), minimum purity 99 % (m/m) (CAS number
25、: 109-99-9). 5.5 p-Toluenesulfonyl isocyanate (TSI), minimum purity 96 % (m/m) (CAS number : 4083-64-1). Maintain a nitrogen pad above this reagent after opening the flask. 5.6 p-Toluenesulfonyl isocyanate (TSI) reagent solution. Pipette 20 ml of TSI (5.5) into a dry 500 ml volumetric flask half fil
26、led with acetonitrile. Make up to the mark with acetonitrile and mix well. This reagent shall be prepared fresh monthly. 5.7 Potassium hydrogen phthalate, primary standard minimum purity 99 %(m/m) dried 2 h at 120 C (CAS number : 877-24-7). 5.8 Tetra-n-butyl ammonium hydroxide standard volumetric so
27、lution, c(CH3(CH2)34NOH) = 0,1 mol/l (CAS number : 2052-49-5). in 2-propanol/methanol. 5.9 Electrolyte: 0,4 mol/l tetraethyl ammonium bromide solution (CAS number : 71-91-0) in ethylene glycol (CAS number:107-21-1). 5.10 Electrolyte: saturated LiCl solution (CAS number : 7447-41-8) in ethanol (CAS n
28、umber : 64-17-5). 6 Apparatus Normal laboratory apparatus, and the following. 6.1 Automatic potentiometer, with drift-controlled data acquisition and dynamic titrimetric dosing equipped with an automatic burette assembly and a magnetic stirrer. 6.2 Electrodes: There are two options for the electrode
29、s definition. 6.2.1 Two electrodes system 6.2.1.1 Glass pH electrode. 6.2.1.2 Ag/AgCl double-junction ground joint diaphragm reference electrode, inner and outer chambers filled with 0,4 mol/l solution of tetraethyl ammonium bromide in ethylene glycol (5.9). or EN 15168:2006 (E) 6 6.2.2 One electrod
30、e system Combined glass pH electrode for titrations in non aqueous media (e.g. Solvotrode1), filled with 0,4 mol/l solution of tetraethyl ammonium bromide in ethylene glycol (5.9). NOTE For electrode maintenance it is recommended to follow the manufacturer instructions. A saturated lithium chloride
31、solution in ethanol (5.10) can also be used as electrolyte to fill the electrodes. 7 Sampling The sample shall be taken and stored in accordance with ISO 607. Samples that are solids at room temperature shall be heated prior to weighing to obtain a clear liquid, at the lowest possible temperature (5
32、0 C to 70 C) to avoid any undesirable changes in the sample. If higher temperatures are required to melt the sample, for example 110 C, then the sample shall be removed from the oven as soon as a clear liquid is obtained. After heating, invert the sample container about twenty times to ensure comple
33、te homogenisation. Samples that are liquid at room temperature only require inversion mixing. 8 Procedure 8.1 Standardization of tetra-n-butyl ammonium hydroxide standard volumetric solution Weigh about 0,18 g of dried potassium hydrogen phthalate (5.7) (m0) to the nearest 0,1 mg into a 100 ml beake
34、r, dissolve it in about 60 ml of freshly boiled water and stir several minutes to ensure complete dissolution. Carry out a potentiometric titration directly with the tetra-n-butyl ammonium hydroxide standard volumetric solution (5.8). Record the volume Vof the tetra-n-butyl ammonium hydroxide standa
35、rd volumetric solution (5.8) at the inflection point of the titration curve. Carry out three to five standardization titrations to obtain a reliable mean value for the 0,1 mol/l tetra-n-butyl ammonium hydroxide concentration (5.8). Calculate the concentration, c, of the tetra-n-butyl ammonium hydrox
36、ide standard volumetric solution (5.8), expressed in moles per litre, using the Equation (1): VMmc=10000(1) where m0is the mass ofpotassium hydrogen phthalate (5.7), in grams; V is the volume, in millilitres, of the tetra-n-butyl ammonium hydroxide standard volumetric solution (5.8) consumed to the
37、inflection point. The results shall be given to four decimal places. 1) Solvotrode is the trade name of a product supplied by Metrohm Ltd. (CH-9101 Herisau, Switzerland). This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN. E
38、quivalent products may be used if they can be shown to lead to the same results.EN 15168:2006 (E) 7 8.2 Test portion Calculate the optimum sample to be weighed, m, expressed in grams, by the Equation (2): ()E40OHVm = (2) where (OHV)Eis the expected hydroxyl value, in milligrams KOH per sample gram.
39、For expected hydroxyl values 2, weigh about 15 g to 20 g of sample as maximum. 8.3 Determination Weigh the calculated mass of the test portion, m, to the nearest 0,1 mg into a clean and dry 100 ml beaker. With a measuring cylinder, add 10 ml of acetonitrile (5.2). Add a magnetic stirring bar and sti
40、r slowly on a magnetic stirrer until the test portion is dissolved (30 s are usually sufficient). NOTE 1 Although acetonitrile has been found to dissolve a wide range of product types and should be used where possible, tetrahydrofuran or pentene stabilized chloroform may be used as solvent for produ
41、cts that may be insoluble in acetonitrile (5.2). Alternatively, 3 ml of toluene (5.3) may be used to dissolve a product, followed immediately by addition of 7 ml of acetonitrile (5.2). Superior potentiometric titration curves are obtained in acetonitrile media. Pipet (10 0,1) ml of TSI reagent (5.6)
42、 into the test solution, cover the beaker with a watch glass and stir slowly on the magnetic stirrer for 5 min. Add 0,5 ml of water to destroy excess of TSI reagent (5.6) and stir for 1 min at slow speed. Add about 60 ml of THF (5.4) and start the titration with 0,1 mol/l tetra-n-butyl ammonium hydr
43、oxide standard volumetric (5.8) solution using the electrodes defined in 6.2. NOTE 2 A set of titration parameters is given in Annex B for advice. After titration rinse the electrode(s) to remove residual organic material and next rinse with water and immerse the electrode bulb in water to maintain
44、good hydration of electrode between titrations. A typical potentiometric titration curve will have two or three inflections as those in Figure C.1. Record the volume (V1) at the first potentiometric end point and the volume (V2) at the second potentiometric end point. Although pH values will not ent
45、er into the calculations, record the “apparent“ pH values at each of the potentiometric inflection points. Perform the test solution analysis in duplicate. EN 15168:2006 (E) 8 9 Calculation and expression of results The experimental hydroxyl value, OHV, in milligrams of KOH per gram of the test port
46、ion, is calculated by the Equation (3): ()m,cVVOHV115612= (3) where V2is the volume of the tetra-n-butyl ammonium hydroxide standard volumetric solution (5.8) corresponding to the second equivalence point, in millilitres; V1is the volume of the tetra-n-butyl ammonium hydroxide standard volumetric so
47、lution (5.8) corresponding to the first equivalence point, in millilitres; c is the concentration of the tetra-n-butyl ammonium hydroxide standard volumetric solution (5.8), in moles per litre The results shall be given to one decimal place if the value is above 100 and to two decimal places if the
48、value is below 100. 10 Precision 10.1 Repeatability limit The absolute 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 exce
49、ed the repeatability limit, r, in more than 5 % of cases. 10.2 Reproducibility limit The absolute difference between two independent single test results, obtained using the same method on identical test material in different laboratories by different operators using different equipment, will not exceed the reproducibility limit, R, in more than 5 % of cases. 11 Test report The test report shall include the following information: a) all information necessary for the identification of the sample tested; b)
