SIST-TS CEN/TS 15604:2008
(Main)Fertilizers - Determination of different forms of nitrogen in the same sample, containing nitrogen as nitric, ammoniacal, urea and cyanamide nitrogen
Fertilizers - Determination of different forms of nitrogen in the same sample, containing nitrogen as nitric, ammoniacal, urea and cyanamide nitrogen
This Technical Specification 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 Annex I of the Regulation (EC) No 2003/2003 [1] containing nitrogen in various forms.
Düngemittel - Bestimmung verschiedener, nebeneinander anwesender Stickstoff-Formen in derselben Probe mit Stickstoff in Form von Ammonium, Nitrat, Harnstoff und Cyanamid
Engrais - Détermination des différentes formes d'azote dans un meme échantillon contentant l'azote sous forme nitrique, ammoniacale, uréique et cyanamidique
Gnojila - Določevanje različnih oblik dušika v istem vzorcu, ki vsebuje dušik v obliki nitrata, amonija, sečnine in cianoamida
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 15604:2008
01-marec-2008
*QRMLOD'RORþHYDQMHUD]OLþQLKREOLNGXãLNDYLVWHPY]RUFXNLYVHEXMHGXãLNY
REOLNLQLWUDWDDPRQLMDVHþQLQHLQFLDQRDPLGD
Fertilizers - Determination of different forms of nitrogen in the same sample, containing
nitrogen as nitric, ammoniacal, urea and cyanamide nitrogen
Düngemittel - Bestimmung verschiedener, nebeneinander anwesender Stickstoff-Formen
in derselben Probe mit Stickstoff in Form von Ammonium, Nitrat, Harnstoff und
Cyanamid
Engrais - Détermination des différentes formes d'azote dans un meme échantillon
contentant l'azote sous forme nitrique, ammoniacale, uréique et cyanamidique
Ta slovenski standard je istoveten z: CEN/TS 15604:2007
ICS:
65.080
SIST-TS CEN/TS 15604:2008 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL SPECIFICATION
CEN/TS 15604
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
July 2007
ICS 65.080
English Version
Fertilizers - Determination of different forms of nitrogen in the
same sample, containing nitrogen as nitric, ammoniacal, urea
and cyanamide nitrogen
Engrais - Détermination des différentes formes d'azote Düngemittel - Bestimmung verschiedener, nebeneinander
dans un même échantillon contentant l'azote sous forme anwesender Stickstoff-Formen in derselben Probe mit
nitrique, ammoniacale, uréique et cyanamidique Stickstoff in Form von Ammonium, Nitrat, Harnstoff und
Cyanamid
This Technical Specification (CEN/TS) was approved by CEN on 8 May 2007 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, Bulgaria, 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
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 15604:2007: E
worldwide for CEN national Members.
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CEN/TS 15604:2007 (E)
Contents Page
Foreword.3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Principle.4
5 Reagents.6
6 Apparatus .9
7 Sampling and sample preparation.14
8 Procedure .15
9 Verification of the result.22
10 Test report .22
Bibliography .23
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CEN/TS 15604:2007 (E)
Foreword
This document (CEN/TS 15604:2007) 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 Technical Specification: Austria, Belgium, Bulgaria, 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.
3
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CEN/TS 15604:2007 (E)
1 Scope
This Technical Specification 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 Annex I of the Regulation (EC) No 2003/2003 [1]
containing nitrogen in various forms.
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.
EN 1482-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample
preparation
EN 12944-1:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 1: General terms
EN 12944-2:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 2: Terms relating
to fertilizers
CEN/TS 15475, Fertilizers — Determination of ammoniacal nitrogen
CEN/TS 15562, Fertilizers — Determination of cyanamide nitrogen
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 document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999
apply.
4 Principle
4.1 Total soluble and insoluble nitrogen
According to the list of standard fertilizers given in Annex I of [1], this 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 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 CEN/TS 15475.
NOTE If analysis shows an insoluble nitrogen content of more than 0,5 %, one concludes that the fertilizer contains
other forms of insoluble nitrogen not included in the list in [1], Annex I.
4
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CEN/TS 15604:2007 (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 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 CEN/TS 15475).
4.2.2.2 In the presence of nitrates, by Kjeldahl digestion on an aliqot part taken from the solution after
reduction according to Ulsch. The ammonia is then determined (by the same method as that described in
CEN/TS 15475).
4.2.3 Total soluble nitrogen with the exception of nitrate nitrogen
By Kjeldahl digestion after elimination in an acid medium of nitrate nitrogen with ferrous sulphate. The
ammonia is then determined (by the same method as that described in CEN/TS 15475).
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 as summarized in 4.2.3 or between total soluble
nitrogen (4.2.2.2) 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 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 + 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
CEN/TS 15475.
4.2.5.2 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
CEN/TS 15475.
4.2.6 Urea nitrogen
4.2.6.1 By conversion using urease, into ammonia which is titrated 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 1.
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CEN/TS 15604:2007 (E)
Table 1 — Determination of urea nitrogen by difference
Nitrate Ammoniacal Cyanamidic
Case Difference
nitrogen nitrogen nitrogen
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 Present 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 distilled or de-mineralized water of grade 3 according to
EN ISO 3696:1995.
5.2 Potassium sulfate
p.a.
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 Potassium nitrate
p.a.
5.6 Ammonium sulfate
p.a.
5.7 Urea
p.a.
5.8 Diluted sulfuric acid
Dilute one volume of sulfuric acid (ρ = 1,84 g/ml) in one volume of water.
20
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CEN/TS 15604:2007 (E)
5.9 Standard solution of sulfuric acid
c = 0,1 mol/l
5.10 Sodium hydroxide solution
aqueous solution of about 30 % (mass concentration), free from ammonia
5.11 Standard solution of sodium or potassium hydroxide
c = 0,2 mol/l, free from carbonates
5.12 Stannous chloride solution
.
Dissolve 120 g of SnCl 2H O in 400 ml of concentrated hydrochloric acid (ρ = 1,18 g/ml) and make up to
2 2 20
1 l with water. The solution shall be perfectly clear and prepared immediately before use.
.
It is essential to check the reducing power of stannous chloride: dissolve 0,5 g of SnCl 2H O in 2 ml of
2 2
concentrated hydrochloric acid (ρ = 1,18g/ml) and make up to 50 ml with water. Then add 5 g of Rochelle
20
salt (potassium sodium tartrate), then a sufficient quantity of sodium bicarbonate for the solution to be alkaline
to litmus paper.
Titrate with a 0,1 mol/l iodine solution in the presence of a starch solution as an indicator.
.
1 ml of 0,1 mol/l iodine solution corresponds to 0,01128 g of SnCl 2H O.
2 2
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 0,1 mol/l iodine solution shall therefore be used.
5.13 Sulfuric acid
ρ = 1,84 g/ml
20
5.14 Diluted hydrochloric acid
one volume of hydrochloric acid (ρ = 1,18 g/ml) plus one volume of water
20
5.15 Acetic acid
96 % to 100 %
5.16 Sulfuric acid solution
containing about 30 % of H SO (mass concentration)
2 4
5.17 Ferrous sulfate
.
crystalline, FeSO 7H O
4 2
5.18 Standard sulfuric acid solution
c = 0,05 mol/l
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CEN/TS 15604:2007 (E)
5.19 Octyl alcohol
5.20 Saturated solution of potassium carbonate
5.21 Standard solution of sodium or potassium hydroxide
c = 0,1 mol/l (free from carbonates)
5.22 Saturated solution of barium hydroxide
5.23 Sodium carbonate solution
at 10 % (mass concentration)
5.24 Hydrochloric acid
c = 2 mol/l
5.25 Standard solution of hydrochloric acid
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
Solution at 5 % in ethanol or methanol (5.32) (do not 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
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 determination.
5.29 Anti-bump granules
washed in hydrochloric acid and calcined
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
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.
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CEN/TS 15604:2007 (E)
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.
5.30.4 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 papers 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 equipment 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.
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CEN/TS 15604:2007 (E)
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 (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 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 1
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CEN/TS 15604:2007 (E)
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 splash 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 (5) for the addition of
sodium hydroxide
3 six-bulb condenser with a spherical joint (No 18) at the entrance and joined 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 cross-section
Figure 2 — Distillation apparatus 2
11
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CEN/TS 15604:2007 (E)
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 18) 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 collected
Figure 3 — Distillation apparatus 3
12
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CEN/TS 15604:2007 (E)
Dimensions in millimetres
Key
1 round-bottomed, long-necked flask of 1 000 ml capacity with a bell mouth
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; the tap may be replaced by a rubber connection with an appropriate clip)
3 six-bulb condenser with a spherical 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 distillate
5 PTFE tap
Figure 4 — Distillation apparatus 4
13
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CEN/TS 15604:2007 (E)
6.2 Apparatus for the determination of ammoniacal nitrogen
According to analytical technique (8.2.5.3).
The apparatus is made up of a specially shaped receptacle with a ground glass neck, with a side neck, a
connecting tube with a splash head and a perpendicular tube for the introduction of air. The tubes can be
connected to the receptacle by means of a simple perforated rubber bung. It is important to give a suitable
shape to the end of the tubes introducing air, since the bubbles of gas should be evenly distributed throughout
the solutions contained in the receptacle and the absorber. The best arrangement consists of small
mushroom-shaped pieces with an external diameter of 20 mm and six openings of 1 mm around the
periphery.
6.3 Apparatus for the determination of urea nitrogen
According to the urease technique (8.2.6.1).
It consists of a 300 ml Erlenmeyer flask, with a separating funnel and a small absorber.
6.4 Rotary shaker (35 to 40 revolutions per min)
6.5 pH meter
6.6 Oven, capable of being maintained at a temperature of 130 °C
6.7 Glassware:
a) pipettes of 2 ml, 5 ml, 10 ml, 20 ml, 25 ml, 50 ml and 100 ml capacity;
b) long-necked Kjeldahl flasks of 300 ml and 500 ml capacity;
c) graduated flasks of 100 ml, 250 ml, 500 ml and 1 000 ml capacity;
d) crucibles of sintered glass, pore diameter, 5 µm to 15 µm;
e) mortars.
7 Sampling and sample preparation
Sampling is not part of the method specified in this document. A recommended sampling method is given in
EN 1482-1 [2].
Sample preparation shall be carried out in accordance with EN 1482-2.
14
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CEN/TS 15604:2007 (E)
8 Procedure
8.1 Total soluble and insoluble nitrogen
8.1.1 In the absence of nitrates
8.1.1.1 Digestion
Weigh, to an accuracy of 0,001 g, a quantity of the sample containing 100 mg of nitrogen at the most. Place it
in the flask of the distillation apparatus (6.1). Add 10 g to 15 g of potassium sulfate (5.2), the catalyst (5.28),
and a few anti-bump granules (5.29). Then add 50 ml of diluted sulfuric acid (5.8), and mix thoroughly. First
heat gently, mixing from time to time, until foam no longer forms. Then heat in such a way that the liquid boils
regularly and keep it boiling for 1 h after the solution has become clear, preventing any organic matter from
sticking to the sides of the flask. Allow to cool. Carefully add about 350 ml of water, with mixing. Ensure that
the dissolution is as complete as possible. Allow to cool and connect the flask to the distillation apparatus
(6.1).
8.1.1.2 Distillation of ammonia
Transfer with a precision pipette, into the receiver of the apparatus, 50 ml of a standard solution of sulfuric
acid 0,1 mol/l (5.9). Add the indicator (5.30.3 or 5.30.4). Ensure that the tip of the condenser is at least 1 cm
below the level of
...
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