1、 ISO 2016 Fertilizers Determination of different forms of nitrogen in the same sample, containing nitrogen as nitric, ammoniacal, urea and cyanamide nitrogen Engrais Dtermination des diffrentes formes dazote dans un mme chantillon contenant lazote sous forme nitrique, ammoniacale, urique et cyanamid
2、ique INTERNATIONAL STANDARD ISO 15604 First edition 2016-05-01 Reference number ISO 15604:2016(E) ISO 15604:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be repro
3、duced 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 address below or ISOs member body in the country of the requester
4、. 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 15604:2016(E)Foreword iv 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Principle 1 4.1 Total soluble and insoluble
5、nitrogen 1 4.2 Forms of soluble nitrogen 2 4.2.1 General 2 4.2.2 Total soluble nitrogen 2 4.2.3 Total soluble nitrogen with the exception of nitrate nitrogen 2 4.2.4 Nitrate nitrogen by difference 2 4.2.5 Ammoniacal nitrogen 2 4.2.6 Urea nitrogen 2 4.2.7 Cyanamide nitrogen 3 5 Reagents 3 6 Apparatus
6、 . 5 7 Sampling and sample preparation .10 8 Procedure10 8.1 Total soluble and insoluble nitrogen .10 8.1.1 In the absence of nitrates 10 8.1.2 In the presence of nitrate 11 8.2 Forms of soluble nitrogen.12 8.2.1 Preparation of the solution to be analysed 12 8.2.2 Total soluble nitrogen .13 8.2.3 To
7、tal soluble nitrogen with the exception of nitrate nitrogen .14 8.2.4 Nitrate nitrogen .14 8.2.5 Ammoniacal nitrogen .15 8.2.6 Urea nitrogen .16 8.2.7 Cyanamide nitrogen .18 9 V erification of the r esult 18 10 Test report 18 Bibliography .19 ISO 2016 All rights reserved iii Contents Page ISO 15604:
8、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 member body interested in a subject for w
9、hich 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 Electrotechnical Commission (IEC) on all
10、 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 of ISO documents should be noted. Th
11、is 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 held responsible for identifying any o
12、r 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 information given for the convenience of user
13、s 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 Barriers to Trade (TBT) see the following
14、 URL: www.iso.org/iso/foreword.html. ISO 15604 was prepared by CEN/TC 260 as EN 15604:2009 and was adopted (without modification other than those stipulated below) by Technical Committee ISO/TC 134, Fertilizers and soil conditioners. Modifications were made as follows: a) 5.2: p.a. = pro analysis =
15、analytical grade; b) 6.2: add “Refer to Figure 1”.iv ISO 2016 All rights reserved INTERNATIONAL ST ANDARD ISO 15604:2016(E) Fertilizers Determination of different forms of nitrogen in the same sample, containing nitrogen as nitric, ammoniacal, urea and cyanamide nitrogen 1 Scope This International S
16、tandard specifies a method for the determination of any one form of nitrogen in the presence of any other form. The method is applicable to any fertilizer provided for in the Regulation (EC) No 2003/2003, Annex I 2containing nitrogen in various forms. 2 Normative references The following documents,
17、in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3696, Water for analytical l
18、aboratory use Specification and test methods ISO 14820-2, Fertilizers and liming materials Sampling and sample preparation Part 2: Sample preparation ISO 25475, Fertilizers Determination of ammoniacal nitrogen EN 12944-1, Fertilizers and liming materials Vocabulary Part 1: General terms EN 12944-2,
19、Fertilizers and liming materials Vocabulary Part 2: Terms relating to fertilizers EN 15562, Fertilizers Determination of cyanamide nitrogen 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 apply. 4 Principle 4.1 Total soluble
20、and insoluble nitrogen According to the list of standard fertilizers given in Regulation (EC) No 2003/2003, Annex I, 2this determination is applicable to products containing calcium cyanamide. In the absence of nitrates, the test sample is mineralized by direct Kjeldahl digestion. In the presence of
21、 nitrates, the test sample is mineralized by Kjeldahl digestion after reduction with the aid of metallic iron and stannous chloride. In both cases, the ammonia is determined according to ISO 25475. NOTE If analysis shows an insoluble nitrogen content of more than 0,5 %, one concludes that the fertil
22、izer contains other forms of insoluble nitrogen not included in the list in Regulation (EC) No 2003/2003, Annex I. 2 ISO 2016 All rights reserved 1 ISO 15604:2016(E) 4.2 Forms of soluble nitrogen 4.2.1 General The forms of soluble nitrogen referred to in 4.2.2 to 4.2.7 are determined from different
23、aliquots taken from the same solution of the test sample. 4.2.2 Total soluble nitrogen 4.2.2.1 In the absence of nitrates, by direct Kjeldahl digestion. The ammonia is then determined (by the same method as that described in ISO 25475). 4.2.2.2 In the presence of nitrates, by Kjeldahl digestion on a
24、n aliquot part taken from the solution after reduction according to Ulsch. The ammonia is then determined (by the same method as that described in ISO 25475). 4.2.3 Total soluble nitrogen with the exception of nitrate nitrogen By Kjeldahl digestion after elimination in an acid medium of nitrate nitr
25、ogen with ferrous sulfate. The ammonia is then determined (by the same method as that described in ISO 25475). 4.2.4 Nitrate nitrogen by difference 4.2.4.1 In the absence of calcium cyanamide, by determining the difference between the nitrogen determined as summarized in 4.2.2.2 and that determined
26、as summarized in 4.2.3 or between total soluble nitrogen (see 4.2.2) and the sum of ammoniacal nitrogen and ureic organic nitrogen (4.2.5 + 4.2.6). 4.2.4.2 In the presence of calcium cyanamide, by determining the difference between the nitrogen determined as summarized in 4.2.2.2 and that determined
27、 as summarized in 4.2.3 or between the nitrogen determined as summarized in 4.2.2.2 and the sum of that determined as summarized in 4.2.5, 4.2.6 and 4.2.7. 4.2.5 Ammoniacal nitrogen 4.2.5.1 Solely in the presence of ammoniacal nitrogen and ammoniacal plus nitrate nitrogen, according to ISO 25475. 4.
28、2.5.2 In the presence of urea nitrogen and/or cyanamide nitrogen by cold distillation after making slightly alkaline, the ammonia is absorbed in a standard solution of sulfuric acid and determined according to ISO 25475. 4.2.6 Urea nitrogen 4.2.6.1 By conversion using urease into ammonia which is ti
29、trated with a standard solution of hydrochloric acid. or 4.2.6.2 By gravimetry with xanthydrol: the co-precipitated biuret can be counted with urea nitrogen without great error, its content remaining generally low in absolute value in compound fertilizers. or 4.2.6.3 By difference according to Table
30、 1.2 ISO 2016 All rights reserved ISO 15604:2016(E) Table 1 Determination of urea nitrogen by difference Case Nitrate nitrogen Ammoniacal nitrogen Cyanamidic nitrogen Difference 1 Absent Present Present (4.2.2.1) - (4.2.5.2 + 4.2.7) 2 Present Present Present (4.2.3) - (4.2.5.2 + 4.2.7) 3 Absent Pres
31、ent Absent (4.2.2.1) - (4.2.5.2) 4 Present Present Absent (4.2.3) - (4.2.5.2) 4.2.7 Cyanamide nitrogen By precipitation as a silver compound, the nitrogen being determined in the precipitate by the Kjeldahl method. 5 Reagents 5.1 General. Use only reagents of recognized analytical grade and distille
32、d or de-mineralized water of grade 3 according to ISO 3696. 5.2 Potassium sulfate, p.a. (p.a. = pro analysis = analytical grade). 5.3 Iron powder, reduced with hydrogen. The prescribed quantity of iron shall be able to reduce at least 50 mg of nitrate nitrogen. 5.4 Potassium thiocyanate, p.a. 5.5 Po
33、tassium nitrate, p.a. 5.6 Ammonium sulfate, p.a. 5.7 Urea, p.a. 5.8 Sulfuric acid diluted. Dilute one volume of sulfuric acid ( 20= 1,84 g/ml) in one volume of water. 5.9 Sulfuric acid, standard solution, c = 0,1 mol/l. 5.10 Sodium hydroxide solution, aqueous solution of about 30 % (mass concentrati
34、on), free from ammonia. 5.11 Sodium or potassium hydroxide, standard solution, c = 0,2 mol/l, free from carbonates. 5.12 Stannous chloride solution. Dissolve 120 g of SnCl 2 2H 2 O in 400 ml of concentrated hydrochloric acid ( 20= 1,18 g/ml) and make up to 1 l with water. The solution shall be perfe
35、ctly clear and prepared immediately before use. It is essential to check the reducing power of stannous chloride: dissolve 0,5 g of SnCl 2 2H 2 O in 2 ml of concentrated hydrochloric acid ( 20= 1,18 g/ml) and make up to 50 ml with water. Then, add 5 g ISO 2016 All rights reserved 3 ISO 15604:2016(E)
36、 of Rochelle salt (potassium sodium tartrate), then a sufficient quantity of sodium bicarbonate for the solution to be alkaline to litmus paper. Titrate with an iodine solution (I 2 ) of c = 0,05 mol/l in the presence of a starch solution as an indicator. 1 ml of iodine solution (I 2 ) of c = 0,05 m
37、ol/l corresponds to 0,011 28 g of SnCl 2 2H 2 O. At least 80 % of the total tin present in the solution thus prepared shall be in bivalent form. For the titration, at least 35 ml of the c = 0,05 mol/l iodine solution (I 2 ) should be used. 5.13 Sulfuric acid, 20= 1,84 g/ml. 5.14 Hydrochloric acid di
38、luted. Mix one volume of hydrochloric acid ( 20= 1,18 g/ml) with one volume of water. 5.15 Acetic acid, 96 % to 100 %. 5.16 Sulfuric acid solution, containing about 30 % of H 2 SO 4(mass concentration). 5.17 Ferrous sulfate, crystalline, FeSO 4 7H 2 O. 5.18 Sulfuric acid standard solution, c = 0,05
39、mol/l. 5.19 Octyl alcohol. 5.20 Potassium carbonate, saturated solution 5.21 Sodium or potassium hydroxide standard solution, c = 0,1 mol/l (free from carbonates). 5.22 Barium hydroxide saturated solution. 5.23 Sodium carbonate solution, at 10 % (mass concentration). 5.24 Hydrochloric acid, c = 2 mo
40、l/l. 5.25 Hydrochloric acid standard solution, c = 0,1 mol/l. 5.26 Urease solution. Suspend 0,5 g of active urease in 100 ml of water. Using hydrochloric acid 0,1 mol/l (5.25), adjust the pH to 5,4, measured by a pH-meter. 5.27 Xanthydrol. Use a solution at 5 % in ethanol or methanol (5.32) (do not
41、use products giving a high proportion of insoluble matter). The solution may be kept for three months in a well-stoppered bottle, away from the light. 5.28 Catalyst. Use 0,3 g to 0,4 g of copper oxide per determination or an equivalent quantity of copper sulfate pentahydrate of 0,95 g to 1,25 g per
42、determination. 5.29 Anti-bump granules, washed in hydrochloric acid and calcined.4 ISO 2016 All rights reserved ISO 15604:2016(E) 5.30 Indicator solutions. 5.30.1 Solution A. Dissolve 1 g of methyl red in 37 ml of sodium hydroxide solution 0,1 mol/l and make up to 1 l with water. 5.30.2 Solution B.
43、Dissolve 1 g of methylene blue in water and make up to 1 l. 5.30.3 Combined indicator solution. Mix one volume of solution A with two volumes of solution B. This indicator is violet in acid solution, grey in neutral solution and green in alkaline solution. Use 0,5 ml (10 drops) of this indicator sol
44、ution. 5.30.4 Methyl red indicator solution. Dissolve 0,1 g of methyl red in 50 ml of 95 % ethanol. Make up to 100 ml with water and filter if necessary. This indicator (four or five drops) may be used instead of that described in 5.30.3. 5.31 Indicator papers, litmus bromothymol blue (or other pape
45、rs sensitive to pH = 6 to pH = 8). 5.32 Ethanol or methanol, solution 95 %. 6 Apparatus 6.1 Distillation apparatus. Consisting of a round-bottomed flask of suitable capacity connected to a condenser by means of a splash head. The equipment is made of borosilicate glass. NOTE The different types of e
46、quipment recommended for this determination are reproduced, showing all the features of construction, in Figures 1, 2, 3 and 4. An automatic distillation apparatus may also be used, provided that the results are statistically equivalent. ISO 2016 All rights reserved 5 ISO 15604:2016(E) Dimensions in
47、 millimetres 1 2 3 4 5 6 a Key 1 round-bottomed, long-necked flask of 1 000 ml capacity 2 distillation tube with a splash head, connected to the condenser by means of a spherical joint (No 18) (the spherical joint for the connection to the condenser may be replaced by an appropriate rubber connectio
48、n) 3 funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide (the tap may likewise be replaced by a rubber connection with a clip) 4 six-bulb condenser with spherical joint (No 18) at the entrance and joined at the issue to a glass extension tube by means of a small
49、 rubber connection (when the connection to the distillation tube is effected by means of a rubber tube, the spherical joint may be replaced by a suitable rubber bung) 5 500 ml flask in which the distillate is collected 6 PTFE tap a Hole. Figure 1 Distillation apparatus 16 ISO 2016 All rights reserved ISO 15604:2016(E) Dimensions in millimetres 1 2 3 4 5 a Key 1 round-bottomed, short-necked flask of 1 000 ml capacity with a spherical joint (No 35) 2 distillation tube with a splash head, equipped with a
