1、Fertilizers Determination of water content (Karl Fischer methods) Part 1 : Methanol as extracting medium The European Standard EN 13466-1:2001 has the status ofa British Standard ICs 65.080 BS EN 13466- 1 1200 1 A present to the responsible European committee any enquiries on the interpretation, or
2、proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. - A list of organizations represented on this committee can be obtained on request to its secretary. Cr oss-r e fer enc e s The British Standards which imp
3、lement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled ?International Standards Correspondence Index?, or by using the ?Find? facility of the BSI Standards Electronic Catalogue. A British Standard does not pur
4、port to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front
5、cover, the EN title page, pages 2 to 10, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. O BSI 10 April 2002 ISBN O 580 39472 7 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 13466-1 October 2001 ICs 65.080 E
6、nglish version Fertilizers - Determination of water content - (Karl Fischer methods) - Part 1 : Methanol as extracting medium Engrais - Dtermination de la teneur en eau (Mthodes Karl Fischer) - Partie 1 : Le mthanol comme milieu dextraction Dngemittel - Bestimmung des Wassergehaltes (Karl- Fischer-V
7、erfahren) - Teil 1 : Methanol als Extraktionsmittel This European Standard was approved by CEN on 18 August 2001. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any al
8、teration. 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 trans
9、lation 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, It
10、aly, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION EUROPISCHES KOMITEE FR NORMUNG COMIT EUROPEN DE NORMALISATION Management Centre: rue de Stassart, 36 B-1050 Brussels O 2001 CEN All rights of exploitation in any form
11、 and by any means reserved worldwide for CEN national Members. Ref. No. EN 13466-1:2001 E EN 13466-1 12001 (E) Contents page Foreword 3 Introduction . 4 1 Scope 5 2 Normative references 5 3 Principle 5 4 Reagents . 5 5 Apparatus . 5 6 Installation and test of the Karl Fischer titrator 6 7 Sampling .
12、 6 8 Procedure . 6 9 Calculation and expression of results . 8 10 Precision . 9 11 Test report 9 Bibliography 10 2 EN 13466-1 12001 (E) Foreword This European Standard has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials“, the secretariat of which is held by DIN. Thi
13、s 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 April 2002, and conflicting national standards shall be withdrawn at the latest by April 2002. According to the CENKENELEC Internal Regulations, the na
14、tional 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, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
15、 3 EN 13466-1 12001 (E) Introduction The water content of fertilizers has a significant effect on their quality and, especially, their storage and handling properties. Water can be present in a number of forms such as free water, bound water and water of crystallization. It is often important to be
16、able to distinguish between these forms of water. The gravimetric methods for determination of water standardized in EN 12048 and EN 12049 have only limited applicability. The Karl Fischer method is applicable to a wide range of fertilizers. However, there are several variations to the basic techniq
17、ue, different formulations of the Karl Fischer reagents are commercially available and a number of different solvents can be used. In this standard, methanol and 2-propanol are used as extracting media to distinguish between the different forms of water present in fertilizers. EN 13466 “Fertilizers
18、- Determination of water content (Karl Fischer methods)“ consists of two parts: - Part I : Methanol as extracting medium - Part 2 : 2-propanol as extracting medium As examples of the difference between methanol and 2-propanol as extracting media methanol gives a result which is a combination of free
19、 water and extracted water of crystallization from the following components of fertilizers: calcium nitrate tetrahydrate (Ca(N03)2.4H20); calcium hydrogen phosphate dihydrate (CaHP04.2H20); calcium sulfate dihydrate (gypsum, CaS04.2H20) calcium sulfate hemihydrate (CaS04.0,5H20); magnesium sulfate h
20、eptahydrate (MgS04.7H20); potassium chloride magnesium sulfate water (1/1/2,75, Kainite, KCI.MgS04.2,75H20); potassium magnesium sulfate hexahydrate (Schoenite, K2SO4.MgSO4.6H2O); potassium magnesium sulfate tetrahydrate (Leonite, K2S04.MgS04.4H20); potassium sulfate calcium sulfate monohydrate (Syn
21、genite, K2SO4CaSO4.H2O); potassium chloride magnesium chloride hexahydrate (Carnallite, KCI. MgCI2.6H20); magnesium nitrate hexahydrate (Mg(N03)2.6H20). Extraction with 2-propanol gives a result which is a combination of free water and extracted water of crystallization from the following components
22、 of fertilizers: calcium nitrate tetrahydrate (Ca(N03)2.4H20); magnesium sulfate heptahydrate (MgS04.7H20); potassium chloride magnesium chloride hexahydrate (Carnallite, KCI.MgCI2.6H20); magnesium nitrate hexahydrate (Mg(N03)2.6H20). 4 EN 13466-1 12001 (E) 1 Scope This European Standard specifies a
23、 Karl Fischer titrimetric method for the determination of the water content of fertilizers based on the use of methanol as extracting medium. The method is applicable to all solid mineral fertilizers. The result (KFM water) includes “free“ water and extracted water of crystallization from the follow
24、ing components of fertilizers: calcium nitrate tetrahydrate (Ca(N03),4H,0); calcium hydrogen phosphate dihydrate (CaHP0;2HZO); calcium sulfate dihydrate (gypsum, CaS04.2H,0), calcium sulfate hemihydrate (CaSO4.0,5H,O); magnesium sulfate heptahydrate (MgS04.7H,0) ; potassium chloride magnesium sulfat
25、e water (1/1/2,75, Kainite, KCI.MgS0;2,75H2O); potassium magnesium sulfate hexahydrate (Schoenite, K,SO;MgSO;6H,O); potassium magnesium sulfate tetrahydrate (Leonite, K,SO;MgSO4.4H,O); potassium sulfate calcium sulfate monohydrate (Syngenite, K,SO;CaSO;H,O); potassium chloride magnesium chloride hex
26、ahydrate (Carnallite, KCI.MgCI;6H2O); magnesium nitrate hexahydrate (Mg(N03);6H,0). Metal oxides and hydroxides soluble in methanol and pyridine will have an effect which can be corrected for, if their content is known. 2 Normative references This European Standard incorporates by dated or undated r
27、eference, 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 Standard only when inco
28、rporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN 1482, Sampling of solid fertilizers and liming materials. 3 Principle Extraction of water from the fertilizer into methanol and titration of the water
29、with a Karl Fischer reagent, previously standardized by titration with a known mass of water. 4 Reagents 4.1 General All reagents shall be of recognized analytical grade. 4.2 Methanol, containing no more than a mass concentration of 500 mg/l water 4.3 Karl Fischer reagent, equivalence from 1 mg to 5
30、 mg water/mI reagent (see Tables 1 and 2). 4.4 Sodium tartrate dihydrate Na2C4H406. 2H20 (15,66 % mass fraction of water). Sodium tartrate dihydrate Na2C4H406 2H20 can be stored over 60 % H2S04 in a desiccator. Check the water content by drying at about 150 OC. 5 Apparatus Ordinary laboratory appara
31、tus and glassware and in particular the following: 5.1 Balance, capable of weighing to the nearest 0,0001 g. 5 EN 13466-1 12001 (E) 5.2 Mortar and pestle. 5.3 5.4 Centrifuge capable of operating at a rate of 3 500 min-. Centrifuge tubes, diameter 43 cm, height 10 cm fitted with rubber stoppers. 5.5
32、Dispersing apparatus : turbine type, minimum rotational frequency 9 500 min-, suitable for introduction into centrifuge tubes (5.4), for instance Ultra TurraxI 5.6 Karl Fischer titrator NOTE There are several titrators on the market for the Karl Fischer method. 6 Installation and test of the Karl Fi
33、scher titrator Follow the instruction manual for the particular titrator used. 7 Sampling Carry out sampling in accordance with EN 1482. 8 Procedure 8.1 Calibration of the Karl Fischer reagent Titrate a known amount of water or sodium tartrate dihydrate (4.4) accurately weighed to the nearest 0,0001
34、 g following the instruction manual for the titrator. NOTE Calibration frequency should be adapted to the frequency of analysis. 8.2 Drift Control the diffusion of water from the air into the titration vessel during the determination following the Instruction Manual for the titrator. Take account of
35、 any recorded drift (md) when expressing results. 8.3 Determination 8.3.1 General If the fertilizer is dispersible in methanol (4.2), the extraction and titration can be carried out in the titration vessel (see 8.3.2). If not, a separate extraction step will be needed (see 8.3.3). Urea, ammonium nit
36、rate and CAN (= calcium ammonium nitrate) are usually dispersible in methanol 8.3.2 Fertilizers dispersible or soluble in methanol 8.3.2.1 Preparation of test portion Rapidly crush the test sample prepared in accordance with clause 7 and immediately weigh a test portion (see Table 1) to the nearest
37、0,OOOlg. Ultra Turrax S25 equipped with dispersing turbine S25KR - 18G is an example of equipment commercially available. This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN of these products. 6 EN 13466-1 12001 (E) titre of
38、KF-Reagent 5 mglml NOTE Products such as urea and ammonium nitrate which are fully soluble in methanol should not be crushed. titre of KF-Reagent 2 mglml Table 1 - Mass of test portion for fertilizers dispersible or soluble in methanol titre of KF-Reagent 5 mglml Expected water content mass fraction
39、 in Yo titre of KF-Reagent 2 mglml 8.3.2.2 Titration Introduce 20 ml of methanol (4.2) into the reaction vessel of the titrator (5.6). Introduce the weighed test portion (8.3.2.1) directly into the reaction vessel of the titrator (5.6). Start stirring and ensure, that the grains of the fertilizer ar
40、e fully dispersed. Titrate with the Karl Fischer reagent (4.3) until the equivalence point is reached following the instruction manual for the titrator. Record the mass m, in milligrams of water, indicated by the titrator. Adapt the dead-time of the titrator to the grain size of the dispersed fertil
41、izer in accordance with the instruction manual of the titrator used. 8.3.3 8.3.3.1 Test portion Weigh a test portion of the test sample, in accordance with clause 7 and Table 2 to the nearest 0,0001 g directly into the previously dried and tared centrifuge tube (5.4). Fertilizers not dispersible in
42、methanol Table 2 - Mass of test portion for fertilizers not dispersible in methanol Expected water content mass fraction in Yo 20 to 50 - 8.3.3.2 Extraction Add 25 ml of methanol (4.2) with a calibrated pipette to the test portion in the centrifuge tube. Insert the dispersing apparatus (5.5) ensurin
43、g that the distance from any part of the dispersing tool to the inner surface of the centrifuge tube is greater than the grain size of the fertilizer. Place the dispersing tool near to the surface of the fertilizer layer. Disperse for 60 s at room temperature at 9 500 min- at least. Make sure that t
44、he temperature during the dispersion-extraction does not exceed 40 OC or, in case of fertilizer containing magnesium sulfate, 25 OC. Repeat the dispersion for a further 60 s if the fertilizer has not been completely dispersed in the first operation. Repeat the extraction if the dispersion is still n
45、ot complete. NOTE The dispersion can be controlled acoustically; the turbine pitch changes once the dispersion is complete. 7 EN 13466-1 12001 (E) 8.3.3.3 Separation Remove the dispersion apparatus from the centrifuge tube and stopper the latter with the rubber stopper. Centrifuge the tube for 5 min
46、. Repeat for 5 min if the supernatant liquid is not clear. 8.3.3.4 Titration Introduce 5,O ml of the clear solution (8.3.3.3) into the reaction vessel of the titrator (5.6). Start stirring. Titrate with the Karl Fischer reagent (4.3) until the equivalence point is reached following the instruction m
47、anual for the titrator. Record the mass ms, in milligrams of water, indicated by the titrator. 8.4 Blank test Carry out a blank test following the procedure specified in 8.3 but omitting the test portion. Record the mass m,. The blank test should be adapted to the same procedure as given in 8.3.2 or
48、 8.3.3, which ever used. 8.5 Replication Repeat the procedure described in 8.3 using a second test portion from the same test sample. After use, the dispersing tool should be cleaned and dried. 8.6 Alternative procedure for a series of samples 8.6.1 If a serial analysis is contemplated for several s
49、amples an alternative procedure may be used provided enough methanol can be held in the titrator reaction vessel to accomodate all the samples and the ensuing quantity of Karl Fischer reagent. The procedure is as given in 8.6.2 to 8.6.8. 8.6.2 Check for drift as described in 8.2. 8.6.3 Introduce 20 ml to 40 ml of methanol (4.2). 8.6.4 Add the Karl Fischer reagent until the equivalence point is reached. Reset the titrator readings to zero. 8.6.5 Introduce the accurately weighed test portion and proceed as described in 8.3.2 or 8.3.3. 8.6.6 Titrate to the equivalenc
