CEN/TS 15476:2006
(Main)Fertilizers - Determination of nitric and ammoniacal nitrogen according to Devarda
Fertilizers - Determination of nitric and ammoniacal nitrogen according to Devarda
This Technical Specification specifies a method for the determination of nitrate and ammoniacal nitrogen with reduction using Devarda alloy (modified for each of the variants a, b and c).
The method is applicable to all nitrogenous fertilizers, including compound fertilizers, in which nitrogen is found exclusively in nitrate form or in ammoniacal and nitrate form.
Düngemittel - Bestimmung von Nitrat- und Ammoniumstickstoff nach Devarda
Engrais - Détermination de l'azote nitrique et ammoniacal selon Devarda
La présente norme expérimentale spécifie une méthode pour détermination de l’azote nitrique et ammoniacal, avec réduction, selon Devarda (modifiée pour chacune des variantes a, b et c).
Cette méthode s’applique à tous les engrais azotés, y compris les engrais composés, dans lesquels l’azote se trouve exclusivement sous forme nitrique ou sous forme ammoniacale et nitrique.
Gnojila – Določevanje nitratnega in amonijevega dušika po Devardi
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2006
*QRMLOD±'RORþHYDQMHQLWUDWQHJDLQDPRQLMHYHJDGXãLNDSR'HYDUGL
Fertilizers - Determination of nitric and ammoniacal nitrogen according to Devarda
Düngemittel - Bestimmung von Nitrat- und Ammoniumstickstoff nach Devarda
Engrais - Détermination de l'azote nitrique et ammoniacal selon Devarda
Ta slovenski standard je istoveten z: CEN/TS 15476:2006
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL SPECIFICATION
CEN/TS 15476
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
September 2006
ICS 65.080
English Version
Fertilizers - Determination of nitric and ammoniacal nitrogen
according to Devarda
Engrais - Détermination de l'azote nitrique et ammoniacal Düngemittel - Bestimmung von Nitrat- und
selon Devarda Ammoniumstickstoff nach Devarda
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 15476:2006: 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 .6
7 Sampling and sample preparation.8
8 Procedure .8
9 Calculation and expression of the result .11
10 Precision.12
11 Test report .12
Annex A (informative) Results of the inter-laboratory tests .13
Bibliography .14
Foreword
This document (CEN/TS 15476:2006) 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 nitrate and ammoniacal nitrogen with
reduction using Devarda alloy (modified for each of the variants a, b and c).
The method is applicable to all nitrogenous fertilizers, including compound fertilizers, in which nitrogen is
found exclusively in nitrate form or in ammoniacal and nitrate form.
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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999
apply.
4 Principle
Reduction of nitrates and nitrites to ammonia in a strongly alkaline solution by means of a metallic alloy
composed of 45 % Al, 5 % Zn and 50 % Cu (Devarda alloy). Distillation of the ammonia and determination of
the yield in a known volume of standard sulfuric acid; titration of the excess sulfuric acid by means of a
standard solution of sodium or potassium hydroxide.
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 Diluted hydrochloric acid
Mix one volume of ρ(HCl) = 1,18 g/ml with one volume of water.
5.3 Sulfuric acid (for variant a)
c = 0,05 mol/l
5.4 Sodium or potassium hydroxide solution (for variant a)
carbonate free, c = 0,1 mol/l
5.5 Sulfuric acid (for variant b, see NOTE 2 in 8.4)
c = 0,1 mol/l
5.6 Sodium or potassium hydroxide solution (for variant b, see NOTE 2 in 8.4)
carbonate free, c = 0,2 mol/l
5.7 Sulfuric acid (for variant c, see NOTE 2 in 8.4)
c = 0,25 mol/l
5.8 Sodium or potassium hydroxide solution (for variant c, see NOTE 2 in 8.4)
carbonate free, c = 0,5 mol/l
5.9 Devarda alloy for analysis
Powdered in such away that a mass fraction of 90 % to 100 % will pass through a sieve with apertures less
than 0,25 mm square, a mass fraction of 50 % to 75 % will pass through a sieve with apertures of less than
0,075 mm square.
Pre-packed bottles containing a maximum of 100 g are recommended.
5.10 Sodium hydroxide solution
30 % of approximately ρ(NaOH) = 1,33 g/ml, ammonia free
5.11 Indicator solutions
5.11.1 Mixed indicator
Solution A: Dissolve 1 g of methyl red in 37 ml of sodium hydroxide solution c = 0,1 mol/l and make up to 1 l
with water.
Solution B: Dissolve 1 g of methylene blue in water and make up to 1 l.
Mix one volume of A with two volumes of 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 solution.
5.11.2 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 may be used (4 to 5 drops) instead of the preceding one. This indicator is red in acid solution
and yellow in alkaline solution.
5.12 Ethanol
with a mass fraction of 95 % to 96 % ethanol
5.13 Sodium nitrate
p. a.
6 Apparatus
6.1 Distillation apparatus
Consisting of a round-bottomed flask of suitable capacity, connected to a condenser by a distillation tube with
a splash head, additionally equipped with a bubble trap on the receiving flask to prevent any loss of ammonia.
The type of apparatus recommended for this determination is reproduced, showing all the features of
construction, in Figure 1.
The equipment is made of borosilicate glass.
An automatic distillation apparatus may be used as well provided that the results are statistically equivalent.
Dimensions in millimetres
Key
1 750 ml or 1 000 ml round-bottomed, long-necked flask with a bell mouth.
2 distillation tube with a splash head and a No 18 spherical joint at the issue
3 elbow tube with a No 18 spherical joint at the entrance, and a drip cone at the issue (a suitable rubber connection may
be used instead of the spherical joint)
4 six-bulb condenser with an extension tube mounted on a rubber bung holding a bubble trap
5 750 ml receiving flask
6 bubble trap to prevent loss of ammonia
Figure 1 — Distillation apparatus
6.2 Pipettes
capacity of 10 ml, 20 ml, 25 ml, 50 ml, 100 ml and 200 ml
6.3 Graduated flask
capacity 500 ml
6.4 Rotary shaker
35 to 40 revolutions per minute
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
According to Table 1, Table 2 or Table 3, depending on the variant chosen weigh to the nearest 0,00
...
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