1、BSI Standards PublicationBS ISO 17319:2015Fertilizers and soil conditioners Determination of water-soluble potassium content Potassium tetraphenylborategravimetric methodBS ISO 17319:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17319:2015.The UK partici
2、pation in its preparation was entrusted to TechnicalCommittee CII/37, Fertilisers and related chemicals.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are r
3、esponsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 76271 0ICS 65.080Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards
4、 Policy and Strategy Committee on 30 June 2015.Amendments issued since publicationDate Text affectedBS ISO 17319:2015 ISO 2015Fertilizers and soil conditioners Determination of water-soluble potassium content Potassium tetraphenylborate gravimetric methodMatires fertilisantes Dosage de la teneur en
5、potassium Mthode gravimtrique au ttraphnylborate de potassiumINTERNATIONAL STANDARDISO17319First edition2015-05-15Reference numberISO 17319:2015(E)BS ISO 17319:2015ISO 17319:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unle
6、ss otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the a
7、ddress below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 17319:2015ISO 17319:2015(E)Foreword iv1 Scope . 12 Normative references 13 Pri
8、nciple 14 Reagents 15 Apparatus and materials 26 Test solution 27 Procedure. 27.1 Aliquot portion of test solution 27.1.1 Procedure in the presence of cyanamide and/or organic materials . 27.1.2 Procedure in the absence of cyanamide and/or organic materials . 37.2 Determination . 37.3 Blank test . 3
9、7.4 Periodic quality control . 38 Expression of results 38.1 Calculation 38.2 Precision . 48.2.1 Ring test . 48.2.2 Repeatability, r 48.2.3 Reproducibility, R .49 Test report . 4Annex A (informative) Report of Method Accuracy . 5Annex B (informative) Interlaboratory testing 13Bibliography .19 ISO 20
10、15 All rights reserved iiiContents PageBS ISO 17319:2015ISO 17319:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO tech
11、nical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
12、 with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria need
13、ed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent r
14、ights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in t
15、his document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers
16、to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 134, Fertilizers and soil conditioners.iv ISO 2015 All rights reservedBS ISO 17319:2015Fertilizers and soil conditioners Determination of water-soluble potassium content Po
17、tassium tetraphenylborate gravimetric method1 ScopeThis International Standard specifies a gravimetric method for the determination of the water-soluble potassium content of test solutions of fertilizers. It is suitable for use in arbitration and for reference purposes.This International Standard is
18、 applicable to those fertilizers containing more than 1,0 % K2O or equivalent amount of K content.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited ap
19、plies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 3696:1987, Water for analytical laboratory use Specification and test methodsISO 5317, Fertilizers Determination of water-soluble potassium content Preparation of the test solution3 Pr
20、inciplePrecipitation of potassium ions present in an aliquot portion of the test solution (previously treated with bromine water and activated charcoal if cyanamide and/or organic materials are present) by sodium tetraphenylborate in a weakly alkaline medium in the presence of disodium ethylenediami
21、ne-tetraacetatedihydrate (EDTA disodium salt) to eliminate interference by ammonium ions and other metal cations.Filtration of the precipitate, drying and weighing.4 ReagentsWARNING Sodium hydroxide is corrosive, bromine is corrosive, oxidative and toxic. The related operations shall be performed in
22、 fume hood. This standard does not point out all possible safety problems, and the user shall bear the responsibility to take proper safety and health measures, and ensure the operations compliant with the conditions stipulated by the related laws and regulations of the state.During the analysis, us
23、e only reagents of recognized analytical grade, and water conforming to grade 3 of ISO 3696:19874.1 Sodium tetraphenylborate, approximately 15 g/L solution.Dissolve 7,5 g of sodium tetraphenylborate NaB(C6H5)4 in 480 ml of water. Add 2 ml of the sodium hydroxide solution (4.4) and 20 ml of a 100 gra
24、m/litre (g/L) solution of magnesium chloride hexahydrate (MgCl26H2O). Stir for 15 min and filter through the filter paper (5.2).This solution may be stored in a plastics bottle for not longer than 1 month. Filter immediately before use.INTERNATIONAL STANDARD ISO 17319:2015(E) ISO 2015 All rights res
25、erved 1BS ISO 17319:2015ISO 17319:2015(E)4.2 Sodium tetraphenylborate, wash solution.Dilute 1 volume of the Sodium tetraphenylborate solution (4.1) with 10 volumes of water.4.3 EDTA, disodium salt, 40 g/l solution.Dissolve 4,0 g EDTA disodium salt in water in 100 ml graduated flask. Make up to the v
26、olume and mix.4.4 Sodium hydroxide, 400 g/L solution.4.5 Phenolphthalein, 5 g/L ethanolic solution.Dissolve 0,5 g of phenolphthalein in 100 ml of 95 % (volume fraction) ethanol.4.6 Bromine water, saturated solution, approximately 3,2 % (w/v) bromine; shelf life of less than 6 months.4.7 Charcoal, ac
27、tivated, which does not adsorb or liberate potassium ions.5 Apparatus and materialsDuring the analysis, use only glassware of grade A, and the following:5.1 Gooch crucibles, having a sintered glass or porcelain disc of porosity grade P 10 or P 16 (pore size index of 4 m to 16 m).5.2 Quantitative fil
28、ter paper (intermediate speed).5.3 Drying oven, capable of being controlled at 120C 5C.5.4 Usual laboratory equipment, including pipettes, beakers (250 ml), and volumetric flasks, etc.6 Test solutionUse the clear solution prepared as specified in ISO 5317, also described as follows:Weigh, to the nea
29、rest 0,001 g, 5 g of the prepared test sample to form the test portion. Transfer the test portion to the flask with 400 ml of water. Bring to a boil and continue to boil for 30 min. Cool the contents of the flask and transfer to the volumetric flask. Dilute to the mark, mix well and filter into a dr
30、y beaker. Discard the first 50 ml of filtrate.7 Procedure7.1 Aliquot portion of test solution7.1.1 Procedure in the presence of cyanamide and/or organic materialsPreparation of the test solution as specified in ISO 5317.Transfer, by means of a pipette, an aliquot portion, V1, of the test solution (C
31、lause 6), containing 50 mg to 100 mg of potassium oxide (K2O), preferably about 80 mg, to a 250 ml beaker. Add 5 ml of the bromine water (4.6) and boil the solution until all the bromine has been removed and then, if necessary, to reduce the volume to less than 100 ml. Allow the solution to cool to
32、ambient temperature and transfer it to a 2 ISO 2015 All rights reservedBS ISO 17319:2015ISO 17319:2015(E)100 ml volumetric flask. Add about 0,5 g of the activated charcoal (4.7) and shake vigorously. Dilute with distilled water to the mark and mix well.Filter the solution and use a pipette to transf
33、er 50 ml of the filtrate into a 250 ml beaker.7.1.2 Procedure in the absence of cyanamide and/or organic materialsTransfer, by means of a pipette an aliquot portion, V1, of the test solution (Clause 6) containing 25 to 50 mg (preferably 40 mg) of K2O to a 250 ml beaker and adjust the volume to appro
34、ximately 50 ml by dilution or evaporation.NOTE If the content of fertilizer sample cannot be specified, use the procedure described in 7.1.1.7.2 DeterminationFurther treat the aliquot portion of the test solution (7.1) as follows.Add 20 ml of the EDTA solution (4.3) and 3 to 5 drops of the phenolpht
35、halein solution (4.5). Add, drop by drop, the sodium hydroxide solution (4.4) until a pink colour appears and then add 1 ml of the sodium hydroxide solution in excess.Slightly boil for 15 min.The solution should remain pink. If it does not, add 1 to 3 drops of the phenolphthalein solution (4.6) and,
36、 if necessary, restore the pink colour by adding, drop by drop, the sodium hydroxide solution. (4.5).Remove the beaker from the steam bath and immediately add, drop by drop, while stirring, 30 mL of the tetraphenylborate solution (4.1).Continue stirring for 1 min then cool rapidly to ambient tempera
37、ture in running water and allow to stand for 15 min.Weigh the filter crucible (5.1) previously dried in the oven (5.3) controlled at 120 5 C, and cooled in a desiccator and then weighed to the nearest 0,000 1 g.Decant the supernatant liquid through the crucible. Rinse the beaker and precipitate 3 to
38、 5 times with a total of about 40 ml of the wash solution (4.2), followed by 5 ml of water.Dry the crucible and precipitate in the oven (5.3) controlled at 120 5 C for 90 minutes, allow to cool in a desiccator and weigh to the nearest 0,000 1 g.7.3 Blank testCarry out a blank test at the same time a
39、s the determination.7.4 Periodic quality controlCarry out a quality control test periodically as the determination using K2SO4standard material.8 Expression of results8.1 CalculationThe potassium content, expressed as a percentage by mass as potassium (K) or as potassium oxide (K2O), is given by For
40、mula (1) and Formula (2).a) if cyanamide and/or organic materials are presentmm mm VmV21 43 001200()() f(1) ISO 2015 All rights reserved 3BS ISO 17319:2015ISO 17319:2015(E)b) if cyanamide and/or organic materials are absentmm mm VmV21 43 001100()() f(2)wherem0is the mass, in grams, of the test porti
41、on;m1is the mass, in grams, of the filter crucible;m2is the mass, in grams, of the crucible and precipitate;m3is the mass, in grams, of the crucible used for the blank test;m4is the mass, in grams, of the crucible used for the blank test and the corresponding precipitate;Vois the volume, in millilit
42、res, of the test portion (volume in which the test portion was dis-solved;V1is the volume, in millilitres, of the aliquot portion of the test portion taken for the determina-tion;f is a factor which, if the potassium content is expressed as potassium (K), is equal to 0,1091 or if the potassium conte
43、nt is expressed as potassium oxide (K2O), is equal to 0.,1314.8.2 Precision8.2.1 Ring testDetails of Ring test on the precision of the method are summarized in Annex A.8.2.2 Repeatability, rRepeatability limit r: 0,19 %8.2.3 Reproducibility, RReproducibility limit R: 0,006 2 m + 0,305 2, in which m
44、represented the concentration of K2O.9 Test reportThe test report shall contain at least the following information:a) all information necessary for the complete identification of the sample;b) test method used with reference to this International Standard (i.e. ISO 17319);c) test results obtained;d)
45、 date of sampling and sampling procedure (if known);e) date when the analysis was finished;f) whether the requirement of the repeatability limit has been fulfilled.All operating details not specified in this standard, or regarded as optional, together with details of any incidents that occurred when
46、 performing the method, which might have influenced the test results.4 ISO 2015 All rights reservedBS ISO 17319:2015ISO 17319:2015(E)Annex A (informative) Report of Method AccuracyA.1 OverviewReview of ISO standard on determination of potassium content in fertilizerThe current effective ISO standard
47、 on determination of potassium content in fertilizer is ISO 5310:1986. ISO 5310:1986 specifies a titrimetric method (volumetric method) for the determination of the potassium content of fertilizers.The principle of ISO 5310:1986 is as follows: Prepare a test solution as specified in ISO 5317 or ISO
48、7407; Precipitate the potassium ions present in an aliquot portion of the test solution (previously treated with bromine water and activated charcoal if cyanamide and/or organic materials presented) by excess amount of sodium tetraphenylborate (NaTPB) in a weakly alkaline medium; Filter and determin
49、e the unreacted NaTPB by back-titration with cetyltrimethylammonium bromide (CTAB) solution, using thiazol yellow (Titan yellow) as the indicator.As a kind of volumetric method, this method would be expected to have an increased possibility of deviation when it is used for analyzing high concentration potassium samples due to the higher dilution ratio.Abolished ISO standard: ISO 5318:1983 (withdrawn in 2008).ISO 5318:1983 specifies a gravimetric method for the determination of the potassium cont
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