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1、DRAFT FOR DEVELOPMENT DD CEN/TS 15478:2006 Fertilizers Determination of total nitrogen in urea ICS 65.080 ? Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI DD CEN/TS 15478:2006 This Draft for Development was pu
2、blished under the authority of the Standards Policy and Strategy Committee on 29 December 2006 BSI 2006 ISBN 0 580 49798 4 National foreword This Draft for Development was published by BSI. It is the UK implementation of CEN/TS 15478:2006. This publication is not to be regarded as a British Standard
3、. It is being issued in the Draft for Development series of publications and is of a provisional nature. It should be applied on this provisional basis, so that information and experience of its practical application can be obtained. Comments arising from the use of this Draft for Development are re
4、quested so that UK experience can be reported to the European organization responsible for its conversion to a European standard. A review of this publication will be initiated not later than 3 years after its publication by the European organization so that a decision can be taken on its status. No
5、tification of the start of the review period will be made in an announcement in the appropriate issue of Update Standards. According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into a European Standard, to exten
6、d the life of the Technical Specification or to withdraw it. Comments should be sent to the Secretary of the responsible BSI Technical Committee at British Standards House, 389 Chiswick High Road, London W4 4AL. The UK participation in its preparation was entrusted to Technical Committee CII/37, Fer
7、tilisers and related chemicals. A list of organizations represented on CII/37 can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Amendments issued since publication A
8、md. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI TECHNICAL SPECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 15478 September 2006 ICS 65.080 English Version Fertilizers -
9、Determination of total nitrogen in urea Engrais - Dtermination de lazote total dans lureDngemittel - Bestimmung von Gesamtstickstoff in Harnstoff This Technical Specification (CEN/TS) was approved by CEN on 24 June 2006 for provisional application. The period of validity of this CEN/TS is limited in
10、itially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make
11、 the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are the national standards bo
12、dies of 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, Switzerland and United Kingdom. EUROPEAN CO
13、MMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2006 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 15478:2006: E Licensed Copy: L
14、ondon South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 Contents Page Foreword3 1 Scope 4 2 Normative references4 3 Terms and definitions .4 4 Principle4 5 Reagents.4 6 Apparatus .5 7 Sampling and sample preparation.10 8 Procedure .
15、10 9 Calculation and expression of the result 11 10 Precision.11 11 Test report12 Annex A (informative) Results of the inter-laboratory tests.13 Bibliography14 CEN/TS 15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolle
16、d Copy, (c) BSI 3 Foreword This document (CEN/TS 15478:2006) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials”, the secretariat of which is held by DIN. This document has been prepared under a mandate given to CEN by the European Commission and the European Free
17、Trade Association. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this CEN Technical Specification: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland
18、, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. CEN/TS 15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 20
19、06, Uncontrolled Copy, (c) BSI 4 1 Scope This Technical Specification specifies a method for the determination of total nitrogen in urea. This method is applied exclusively to urea fertilizers which are nitrate free. 2 Normative references The following referenced documents are indispensable for the
20、 application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. prEN 1482-2, Fertilizers and liming materials Sampling and sample preparation Part 2: Sample preparation EN 1
21、2944-1:1999, Fertilizers and liming materials Vocabulary Part 1: General terms EN 12944-2:1999, Fertilizers and liming materials Vocabulary Part 2: Terms relating to fertilizers (including corrigendum AC:2000) EN ISO 3696:1995, Water for analytical laboratory use Specification and test methods (ISO
22、3696:1987) 3 Terms and definitions For the purposes of this Technical Specification, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999 apply. 4 Principle Urea is transformed quantitatively into ammonia by boiling in the presence of sulfuric acid. The ammonia thus obtained is dis
23、tilled from an alkaline medium, the distillate being collected in an excess of standard sulfuric acid. The excess acid is titrated by means of a standard alkaline solution. 5 Reagents 5.1 General Use only reagents of recognized analytical grade and distilled or demineralized water, free from carbon
24、dioxide and all nitrogenous compounds (grade 3 according to EN ISO 3696:1995). 5.2 Potassium sulfate Kjeldahl tablets, 5 g/tablet containing 100 parts K2SO4 to 1 part selenium 5.3 Sulfuric acid concentrated (20 = 1,84 g/ml) 5.4 Sodium hydroxide solution approximately NaOH 500g/l CEN/TS 15478:2006 Li
25、censed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 5.5 Sulfuric acid c = 0,05 mol/l, to use for the blank test. 5.6 Sodium or potassium hydroxide solution carbonate free, c = 0,1 mol/l, to use for the blank test.
26、5.7 Sulfuric acid c = 0,5 mol/l 5.8 Sodium or potassium hydroxide solution carbonate free, c = 1,0 mol/l 5.9 Indicator solutions 5.9.1 Mixed indicator Solution A: Dissolve 1 g of methyl red in 37 ml of 0,1 mol/l sodium hydroxide solution and make up to one litre with water. Solution B: Dissolve 1 g
27、of methylene blue in water and make up to one litre. Mix one volume of A with two volumes of B. This indicator is violet in an acid solution, grey in a neutral solution and green in an alkaline solution; use 0,5 ml (10 drops). 5.9.2 Methyl red indicator solution Dissolve 0,1 g of methyl red in 50 ml
28、 of 95 % ethanol and make up to 100 ml with water. Filter if necessary. This indicator (4 or 5 drops) may be used instead of the preceding one. This indicator is red in acid solution and yellow in alkaline solution. 5.10 Anti-bump granules pumice stone, washed in hydrochloric acid and calcined. 5.11
29、 Urea p. a. 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 equipment recommended for this determination are reproduced showin
30、g all the features of construction in Figures 1, 2, 3, and 4. Automatic distillation apparatus may be used as well provided that the results are statistically equivalent. CEN/TS 15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006,
31、Uncontrolled Copy, (c) BSI 6 Dimensions in millimetres 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
32、appropriate rubber connection) 3 funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide 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 rubber connection (when the connection t
33、o 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 (the tap may likewise be replaced by a rubber connection with a clip) Figure 1 Distillation apparatus 1 CEN/TS
34、15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 7 Dimensions in millimetres Key 1 round-bottomed, short-necked flask of 1 000 ml capacity with a spherical joint (No 35) 2 distillation tube with a spl
35、ash head, equipped with a spherical joint (No 35) at the entrance and a spherical joint (No 18) at the issue, connected at the side to a funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide 3 six-bulb condenser with a spherical joint (No 18) at the entrance and j
36、oined at the issue to a glass extension tube by means of a small rubber connection 4 500 ml flask in which the distillate is collected 5 PTFE-tap a enlarged description Figure 2 Distillation apparatus 2 CEN/TS 15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun
37、Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 8 Dimensions in millimetres Key 1 round-bottomed, long-necked flask of 750 ml or 1 000 ml capacity with, a bell mouth 2 distillation tube with a splash head and a spherical joint (No 18) at the issue 3 elbow tube with a spherical joint (No 1
38、8) at the entrance, and a drip cone (the connection to the distillation tube may be effected by means of a rubber tube instead of a spherical joint) 4 six-bulb condenser joined at the issue to a glass extension tube by means of a small rubber connection 5 500 ml flask in which the distillate is coll
39、ected Figure 3 Distillation apparatus 3 CEN/TS 15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 9 Dimensions in millimetres Key 1 round-bottomed, long-necked flask of 1 000 ml capacity with a bell mou
40、th 2 distillation tube with a splash head and a spherical joint (No 18), at the issue, connected at the side to a funnel with a polytetrafluoroethylene (PTFE) tap (5) for the addition of sodium hydroxide (a suitable rubber bung may be used instead of the spherical joint 3 six-bulb condenser with a s
41、pherical joint (No 18) at the entrance, joined at the issue, by a rubber connection, to a glass extension tube (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) 4 500 ml flask for the collection of the
42、distillate 5 PTFE-tap (the tap may be replaced by a rubber connection with an appropriate clip) Figure 4 Distillation apparatus 4 CEN/TS 15478:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:41:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 10 6.2 Graduat
43、ed flask capacity 500 ml 7 Sampling and sample preparation Sampling is not part of the method specified in this document. A recommended sampling method is given in prEN 1482-1. Sample preparation shall be carried out in accordance with prEN 1482-2. 8 Procedure 8.1 Preparation of the solution Weigh t
44、o the nearest 0,001 g about 500 mg of the prepared sample and transfer with 10 ml demineralized water to a 800 ml Kjeldahl flask. Add, while gently swirling 30 ml sulfuric acid (5.3) and 1 Kjeldahl tablet (5.2). 8.2 Analysis of the solution 8.2.1 Digestion step Put the Kjeldahl flask in a fume cupbo
45、ard. Place on a heating device and heat until boiling, with an input that is required to bring 250 ml of water at 25 C to a “rolling boil“ in 20 min to 30 min. Continue to heat the flask and contents for approximately 1 h, until dense white fumes of sulfuric acid are escaping for at least 15 min. Al
46、low the flask to cool to 25 C. 8.2.2 Distillation step Measure into a 500 ml Erlenmeyer receiving flask 30,00 ml of the 0,5 mol/l sulfuric acid solution (5.7). Add 270 ml water and add four or five drops of the indicator solution (5.9.) and place the Erlenmeyer flask in such a way that the end of th
47、e delivery tube is at least 3 cm below the surface of the liquid. Add 250 ml water to the Kjeldahl flask and several grains of pumice stone (5.10) in order to control the boiling. Assemble the distillation apparatus and taking care to avoid any loss of ammonia, add to the contents of the Kjeldahl fl
48、ask carefully 120 ml of the sodium hydroxide solution (5.4). Agitate the flask to thoroughly mix the contents. Apply heat increasing the rate of heating progressively until finally the contents of the flask are boiling briskly. Most of the ammonia is expelled within 15 min. Continue the distillation
49、 until 150 ml of distillate has been collected. Then lower the Erlenmeyer flask receiver so that the end of the delivery tube is out of the liquid and continue the distillation for a few more minutes. Rinse the outside of the delivery tube with a small amount of water into the Erlenmeyer flask. Back titrate the excess of acid with the 1,0 mol/l sodium hydroxide solution (5.8) to the neutral colour of the indicator (5.9). 8.3 Blank At the same time as the determination carry out a