SIST-TS CEN/TS 15478:2006
(Main)Fertilizers - Determination of total nitrogen in urea
Fertilizers - Determination of total nitrogen in urea
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.
Düngemittel - Bestimmung von Gesamtstickstoff in Harnstoff
Engrais - Détermination de l'azote total dans l'urée
La présente Spécification Technique spécifie une méthode de détermination de l’azote total dans l’urée. Cette méthode s’applique uniquement aux engrais à base d’urée exempts de nitrate.
Gnojila – Določevanje celotnega dušika v sečnini
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Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2006
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Fertilizers - Determination of total nitrogen in urea
Düngemittel - Bestimmung von Gesamtstickstoff in Harnstoff
Engrais - Détermination de l'azote total dans l'urée
Ta slovenski standard je istoveten z: CEN/TS 15478:2006
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL SPECIFICATION
CEN/TS 15478
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
September 2006
ICS 65.080
English Version
Fertilizers - Determination of total nitrogen in urea
Engrais - Détermination de l'azote total dans l'urée Düngemittel - 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 initially 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 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 bodies 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 COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 15478:2006: E
worldwide for CEN national Members.
Contents Page
Foreword.3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Principle.4
5 Reagents.4
6 Apparatus .5
7 Sampling and sample preparation.10
8 Procedure .10
9 Calculation and expression of the result .11
10 Precision.11
11 Test report .12
Annex A (informative) Results of the inter-laboratory tests .13
Bibliography .14
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 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, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden,
Switzerland and the United Kingdom.
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 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 12944-1:1999, 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 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 distilled 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
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 K SO to 1 part selenium
2 4
5.3 Sulfuric acid
concentrated (ρ = 1,84 g/ml)
5.4 Sodium hydroxide solution
approximately NaOH 500g/l
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.
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 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 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 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 showing 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.
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 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 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 (the tap may likewise be replaced by a rubber conn
...
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