1、 ISO 2016 Fertilizers Determination of extracted phosphorus Engrais Dosage du phosphore extrait INTERNATIONAL STANDARD ISO 15959 First edition 2016-07-15 Reference number ISO 15959:2016(E) ISO 15959:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerlan
2、d All rights reserved. Unless 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 request
3、ed from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 15959:2016(E)Foreword iv 1 Scope . 1 2 Normati
4、ve references 1 3 T erms and definitions . 1 4 Principle 1 5 Sampling and sample preparation 1 6 Reagents 1 7 Apparatus . 2 8 Procedure. 3 8.1 Treatment of the solution 3 8.2 Hydrolysis 3 8.3 Weighing the crucible 3 8.4 Precipitation 3 8.5 Filtering and washing 3 8.6 Drying and weighing 4 8.7 Blank
5、test . 4 8.8 Verification . 4 9 Calculation and expression of the result . 4 10 Precision . 5 10.1 Interlaboratory tests 5 10.2 Repeatability . 5 10.3 Reproducibility . 5 11 Test report . 6 Annex A (informative) Statistical results of the interlaboratory test . 7 Bibliography 9 ISO 2016 All rights r
6、eserved iii Contents Page ISO 15959:2016(E) Foreword ISO (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 technical committees. Each membe
7、r 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 with the International Elec
8、trotechnical 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 needed for the different types
9、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 rights. ISO shall not be he
10、ld 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 this document is informati
11、on 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 conformit y assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barri
12、ers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html. ISO 15959 was prepared by CEN/TC 260 as CEN/TS 15959:2009 and was adopted (without modification other than that stipulated below) by Technical Committee ISO/TC 134, Fertilizers and soil conditioners. The following changes have
13、been made: potassium dihydrogen phosphate has been added to the reagents (Clause 6); CEN/TS 15956, CEN/TS 15957 and CEN/TS 15958 have been updated to EN standards; other editorial changes.iv ISO 2016 All rights reserved INTERNATIONAL ST ANDARD ISO 15959:2016(E) Fertilizers Determination of extracted
14、 phosphorus 1 Scope This International Standard specifies a method for the determination of phosphorus in fertilizer extracts. The method is applicable to all extracts of fertilizers for the determination of the different forms of phosphorus as phosphorus soluble in mineral acids, water soluble phos
15、phorus, phosphorus soluble in solutions of ammonium citrate, phosphorus soluble in 2 % citric acid and phosphorus soluble in 2 % formic acid. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. Fo
16、r dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 14820-2, Fertilizers and liming materials Sampling and sample preparation Part 2: Sample preparation EN 12944-1, Fertilizers and liming ma
17、terials and soil improvers Vocabulary Part 1: General terms EN 12944-2, Fertilizers and liming materials and soil improvers Vocabulary Part 2: Terms relating to fertilizers 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions given in EN 12944-1 and EN 12944-2 appl
18、y. 4 Principle After possible hydrolysis, phosphorus is precipitated in an acid media in the form of quinoline phosphomolybdate. After filtering and washing, the precipitate is dried at 250 C and weighed. In the above mentioned conditions, no interfering action is exerted by the compounds likely to
19、be found in the solution (mineral and organic acids, ammonium ions, soluble silicates, etc.) if a reagent based on sodium molybdate or ammonium molybdate is used in the precipitation. 5 Sampling and sample preparation Sampling is not part of the method specified in this International Standard. A rec
20、ommended sampling method is given in ISO 14820-1. Sample preparation shall be carried out in accordance with ISO 14820-2. Grinding of the laboratory sample is recommended for homogeneity reasons. 6 Reagents 6.1 Water, distilled or demineralized. ISO 2016 All rights reserved 1 ISO 15959:2016(E) 6.2 C
21、oncentrated nitric acid, p = 1,40 g/ml. 6.3 Preparation of reagents 6.3.1 Preparation of the reagent based on sodium molybdate Solution A: Dissolve 70 g of sodium molybdate dihydrate in 100 ml of distilled water. Solution B: Dissolve 60 g of citric acid monohydrate in 100 ml of distilled water and a
22、dd 85 ml concentrated nitric acid (6.2). Solution C: Stir solution A into solution B to obtain solution C. Solution D: To 50 ml of distilled water, add 35 ml of concentrated nitric acid (6.2), then 5 ml of freshly distilled quinoline. Add this solution to solution C, mix thoroughly and leave standin
23、g overnight in the dark. After this, make up to 500 ml with distilled water, mix again, and filter through a sintered glass funnel (7.7). 6.3.2 Preparation of the reagent based on ammonium molybdate Solution A: In 300 ml of distilled water, dissolve 100 g of ammonium molybdate while heating gently a
24、nd stirring from time to time. Solution B: Dissolve 120 g of citric acid monohydrate in 200 ml of distilled water, add 170 ml of concentrated nitric acid (6.2). Solution C: Add 10 ml of freshly distilled quinoline to 70 ml of concentrated nitric acid (6.2). Quinoline can be purchased commercially an
25、d can be used instead of freshly distilled. Also, the stock solution of quinolone should be examined periodically for colour degradation and replaced with a new stock when necessary. Solution D: Slowly pour, stirring well, solution A into solution B. After thoroughly mixing, add solution C to this m
26、ixture and make up to 1 l. Leave standing for two days in a dark place and filter through a sintered glass funnel (7.7), or filter paper of similar porosity. The reagents 6.3.1 and 6.3.2 may be used in the same way, both shall be kept in the dark in stoppered polyethylene bottles. 6.4 Potassium dihy
27、drogen phosphate, that containing 0,01 g P 2 O 5 . 7 Apparatus 7.1 Standard laboratory equipment. 7.2 500 ml Er lenme y er f lask, with a wide neck. 7.3 Graduated pipettes, of 10 ml, 25 ml and 50 ml. 7.4 Filter crucible, with porosity of 5 m to 20 m. 7.5 Buchner flask. 7.6 Drying oven, regulated at
28、(250 10) C. 7.7 Sintered glass funnel, with porosity of 5 m to 20 m or filter paper of similar porosity.2 ISO 2016 All rights reserved ISO 15959:2016(E) 8 Procedure 8.1 Treatment of the solution With a pipette (7.3), take an aliquot containing about 0,01 g of P 2 O 5as prescribed in Table 1 from the
29、 fertilizer prepared and previously extracted (see References 3, 4, 5, 6, 7, 8, 9, 10 and 11). Place the aliquot in the Erlenmeyer flask (7.2). Add 15 ml of concentrated nitric acid (6.2) and dilute with water to about 100 ml. When the solution to be precipitated contains more than 15 ml of citrate
30、solution (neutral citrate, Petermann, or Joulie alkaline citrate), an amount of 21 ml of concentrated nitric acid (6.2) shall be added. Table 1 Determination of the aliquot parts of the phosphate solutions % P 2 O 5in the fertilizer % P in the fertilizer Sample for analysis g Dilution to ml Sample m
31、l Dilution to ml Sample to be precipitat- ed ml Quinoline phospho- molybdate conversion factor (F), in % P 2 O 5 Quinoline phospho- molybdate conversion factor (F), in % P 5 to 10 2,2 to 4,4 1 5 500 500 50 10 32,074 32,074 13,984 13,984 10 to 25 4,4 to 11,0 1 5 500 500 50 500 25 50 64,148 64,148 27,
32、968 27,968 25 11 1 5 500 500 50 500 10 25 160,370 128,296 69,921 55,937 8.2 Hydrolysis If the presence of metaphosphates, pyrophosphates, or polyphosphates is suspected in the solution, carry out the hydrolysis as follows. Bring the content of the Erlenmeyer flask (7.2) to a boil slowly and keep at
33、this temperature until hydrolysis is completed. This usually takes 1 h. Care shall be taken to avoid losses by splashing and excessive evaporation which could reduce the initial volume by more than half, by fitting a reflux condenser. After hydrolysis, make up to the initial volume with water (6.1).
34、 8.3 Weighing the crucible Dry the filter crucible (7.4) for at least 15 min in the drying oven (7.6) set at (250 10) C. Cool in a desiccator and weigh to the nearest 0,000 1 g. 8.4 Precipitation Heat the acid solution contained in the Erlenmeyer flask (7.2) until it begins to boil. Then start the p
35、recipitation of the quinoline phosphomolybdate by adding 40 ml of the precipitating reagent (6.3.1 or 6.3.2) drop-wise, stirring continuously. To precipitate phosphate solutions containing more than 15 ml of citrate solution (neutral citrate, Petermann or Joulie) which have been acidified with 21 ml
36、 of concentrated nitric acid (see 8.1), an amount of 80 ml of the precipitating reagent shall be used. Place the Erlenmeyer flask in a hot water bath (temperature 80 C), leave it there for 15 min, shaking it from time to time. Remove the flask from the water bath and allow to cool prior to filtering
37、 the solution 8.5 Filtering and washing Filter the solution under vacuum by decantation. Wash the precipitate in the Erlenmeyer flask (7.2) with 30 ml of water (6.1). Decant and filter the solution. Repeat this process five times. Quantitatively ISO 2016 All rights reserved 3 ISO 15959:2016(E) trans
38、fer the rest of the precipitate into the crucible, washing it with water. Wash four times with 20 ml of water, allowing the liquid to drain from the crucible before each addition. Dry the precipitate thoroughly. 8.6 Drying and weighing Wipe the outside of the crucible with a filter paper or cleaning
39、 tissue. Place this crucible in a drying oven (7.6) and keep it there until its mass remains constant, at a temperature of 250 C (usually 15 min but not to exceed 30 min); leave it to cool in the desiccator at ambient temperature and weigh rapidly. 8.7 Blank t est For each series of determinations,
40、carry out a blank test using only the reagents and solvents in the proportions used in the extraction (citrate solution, etc.) and allow for them in the calculation of the final result. 8.8 V erification Carry out the determination using an aliquot part of a potassium dihydrogen phosphate solution c
41、ontaining 0,01 g of P 2 O 5(6.4). 9 Calculation and expression of the result If the samples for analysis and dilutions are used according to Table 1, calculate the mass fraction, w P , in percent, according to Formula (1): (1) If the samples for analysis and dilutions are used according to Table 1,
42、calculate the mass fraction, w , in percent, according to Formula (2): (2) wherem 1 is the mass, in grams, of the quinoline phosphomolybdate;m 2 is the mass, in grams, of the quinoline phosphomolybdate obtained in the blank test;F and F are factors given in the last two columns of Table 1. If the sa
43、mples for analysis and dilutions differ from those of Table 1, calculate the mass fraction, w P , in percent, according to Formula (3): (3) If the samples for analysis and dilutions differ from those of Table 1, calculate the mass fraction, w , in percent, according to Formula (4): (4) where4 ISO 20
44、16 All rights reserved ISO 15959:2016(E)m 1 is the mass, in grams, of the quinoline phosphomolybdate;m 2 is the mass, in grams, of the quinoline phosphomolybdate obtained in the blank test;f and f are factors of quinoline phosphomolybdate into P 2 O 5= 0,032 074, ( f ) or into P = 0,013 984 ( f); D
45、is the dilution factor; M is the mass, in grams, of the test portion analyzed. 10 Precision 10.1 Interlaboratory tests Interlaboratory tests have been carried out in 2008 based on extraction methods according to EN 15956, EN 15957 and EN 15958. The number of participating laboratories and different
46、fertilizer extract samples are mentioned in Annex A and Tables A .1 to A.3. Repeatability and reproducibility were calculated according to ISO 5725-2. The values derived from these interlaboratory tests may not be applicable to concentration ranges and matrices other than those given in Annex A. 10.
47、2 Repeatability The absolute difference between two independent single test results, obtained with 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, in more than 5 % of the cases, exceed the valu
48、es of r given in Table 2. 10.3 Reproducibility The absolute difference between two single test results, obtained with the same method on identical test material in different laboratories by different operators using different equipment, will not, in more than 5 % of the cases, exceed values of R giv
49、en in Table 2. Table 2 Mean values, repeatability and reproducibility limits Sample (extraction according to EN 15956) x % r % R % NP (DAP) 46,51 0,35 1,17 NPK (16 16 8 + 4S) 16,13 0,21 0,41 TSP 49,35 0,48 1,38 Sample (extraction according to EN 15957) x % r % R % NP (DAP) 46,22 0,24 1,07 NPK (16 16 8 + 4S) 16,08 0,18 0,41 TSP 48,34 0,33 1,09 Sample (ext
