EN 15749:2022

SLOVENSKI STANDARD
01-marec-2023
Nadomešča:
SIST EN 15749:2010
Gnojila - Določevanje sulfatov s tremi različnimi metodami
Fertilizers - Determination of sulfates content using three different methods
Düngemittel - Bestimmung von Sulfat mit drei verschiedenen Verfahren
Engrais - Dosage des sulfates selon trois méthodes différentes
Ta slovenski standard je istoveten z: EN 15749:2022
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 15749
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2022
EUROPÄISCHE NORM
ICS 65.080 Supersedes EN 15749:2009
English Version
Fertilizers - Determination of sulfates content using three
different methods
Engrais - Dosage des sulfates selon trois méthodes Düngemittel - Bestimmung von Sulfat mit drei
différentes verschiedenen Verfahren
This European Standard was approved by CEN on 3 July 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 15749:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Sampling and sample preparation . 6
6 Method A – Gravimetric method . 6
7 Method B – ICP-OES method . 7
8 Method C – IC method . 11
9 Precision of methods A, B and C . 17
10 Test report . 19
Annex A (informative) Statistical results of the inter-laboratory tests. 20
Annex B (informative) Statistical results of the inter-laboratory tests of VDLUFA . 23
Annex C (informative) Statistical results of the inter-laboratory tests of Spanish Proficiency
Testing Program . 26
Bibliography . 28

European foreword
This document (EN 15749:2022) has been prepared by Technical Committee CEN/TC 260 “Fertilizers
and liming materials”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2023, and conflicting national standards shall
be withdrawn at the latest by February 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 15749:2009.
In comparison with the previous edition, the following technical modifications have been made:
— update of the normative references;
— Formula (18) has been corrected;
— addition of more data as result of inter-laboratory tests, Annex B and Annex C.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
This document specifies three different methods for the determination of sulfur. Based on the statistical
results of the inter-laboratory tests, obtained with the same samples, the three methods produce
equivalent results, therefore all three methods can be used, depending on the decision of the user and the
availability of equipment.
1 Scope
This document specifies three different methods (Methods A, B and C) for the determination of sulfur
present in fertilizer extracts in the form of sulfates. Method A specifies the gravimetric method. Method B
specifies the method using inductively coupled plasma optical spectrometry (ICP-OES). Method C
specifies the method using ion chromatography (IC).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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, Fertilizers and liming materials and soil improvers - Vocabulary - Part 1: General terms
EN 12944-2, Fertilizers and liming materials and soil improvers - Vocabulary - Part 2: Terms relating to
fertilizers
EN 15925, Fertilizers - Extraction of total sulfur present in various forms
EN 15926, Fertilizers - Extraction of water soluble sulfur where the sulfur is in various forms
EN 15960, Fertilizers - Extraction of total calcium, total magnesium, total sodium and total sulfur in the
forms of sulfates
EN 15961, Fertilizers - Extraction of water-soluble calcium, magnesium, sodium and sulfur in the form of
sulfates
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 and EN 12944-2 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 Principle
4.1 Method A: Gravimetric method
Sulfur is extracted from the sample according to the methods described in EN 15925, EN 15926,
EN 15960 or EN 15961 and determined based on the gravimetric determination as barium sulfate.
4.2 Method B: ICP-OES
Sulfur is extracted from the sample according to the methods described in EN 15925, EN 15926,
EN 15960 or EN 15961 and its concentration in the extract is measured by inductively coupled plasma-
optical emission spectrometry (ICP-OES).
4.3 Method C: IC
Sulfur is extracted from the fertilizer according to the methods described in EN 15925, EN 15926,
EN 15960 or EN 15961 in the form of sulfate. The sulfate concentration of the extract is measured by ion
chromatography (IC) equipped with a suppressor device and a conductivity detector.
5 Sampling and sample preparation
Sampling is not part of the methods specified in this document. A recommended sampling method is given
in EN 1482-1 [1].
Sample preparation shall be carried out in accordance with EN 1482-2.
6 Method A – Gravimetric method
6.1 Reagents
Use only reagents of recognized analytical grade.
6.1.1 Water, distilled or demineralized (grade 3 according to EN ISO 3696:1995).
6.1.2 Diluted hydrochloric acid.
Mix one volume of mass concentration ρ(HCl) = 1,18 g/ml with one volume of water.
6.1.3 Barium chloride solution, ρ(BaCl .2 H O) = 122 g/l.
2 2
6.1.4 Silver nitrate solution, ρ(AgNO ) = 5 g/l.
6.2 Apparatus
6.2.1 Porcelain crucibles.
6.2.2 Hot water bath.
6.2.3 Drying oven, set at (105 ± 1) °C.
6.2.4 Electric oven, set at (800 ± 50) °C.
6.3 Procedure
6.3.1 Sampling of the solution
Pipette an aliquot part of one of the extraction solutions containing between 20 mg and 100 mg of sulfur
or 50 mg and 250 mg of SO .
Place this aliquot in a beaker of suitable capacity. Add 20 ml of diluted hydrochloric acid (6.1.2). Make up
to about 300 ml with water.
6.3.2 Preparation of the precipitate
Bring the solution to the boil. Add, drop by drop, about 20 ml of the barium chloride solution (6.1.3) while
stirring the solution vigorously. Boil for a few minutes.
Place the beaker, covered with a watch glass, in a boiling hot water bath (6.2.2) for approximately 1 h.
Then leave standing hot (approximately 60 °C) until the supernatant liquor is clear. Decant the clear
solution through a slow filtration ash-free filter. Wash the precipitate several times with hot water.
Continue to wash the precipitate on the filter until the filtrate is chloride free. This can be checked by
using a silver nitrate solution (6.1.4).
6.3.3 Incineration and weighing of the precipitate
Place the filter paper and precipitate in a porcelain crucible (6.2.1) previously weighed to the nearest
0,1 mg.
Dry in the oven (6.2.3) and ash at approximately 800 °C for approximately half an hour (6.2.4). Allow to
cool in a desiccator and weigh to 0,1 mg.
6.4 Calculation and expression of the result
1 mg of barium sulfate corresponds to 0,137 mg of sulfur or to 0,343 mg of SO .
Calculate the sulfates content expressed as sulfur, w , as mass fraction in percent of the fertilizer
S
according to Formula (1):
V
wm=××0,0137 (1)
S1
Vm×
where
m is the mass of the barium sulfate precipitate, in mg;
m is the mass of the test portion, in g;
V is the volume of the extraction solution, in ml;
V is the aliquot volume, in ml.
Calculate the SO content, w , as mass fraction in percent of the fertilizer according to Formula (2):
3 SO3
ww×2,5 (2)
SO3 S
7 Method B – ICP-OES method
7.1 Reagents
Use only reagents of recognized analytical grade.
Stock solutions shall be replaced after a maximum of one year, but the standard solution shall be freshly
prepared monthly as a minimum.
7.1.1 Water, conforming to grade 2 of EN ISO 3696:1995.
7.1.2 Hydrochloric acid, ρ approximately 1,18 g/ml.
7.1.3 Diluted hydrochloric acid.
Mix 40 ml of hydrochloric acid (7.1.2) in 1 l of water.
=
7.1.4 Sulfur stock solution, corresponding to 1 000 mg/l sulfur.
Dry in a pre-treatment step a sufficient quantity of sodium sulfate (Na SO ) at 105 °C for approximately
2 4
1 h in order to dispose of at least the necessary amount of dried sodium sulfate (Na SO ). Let cool in a
2 4
desiccator. Weigh to the nearest 0,1 mg, approximately 4,437 5 g of sodium sulfate (Na SO ). Dissolve the
2 4
weighted mass in a small quantity of water in volumetric flasks of nominal capacity of 1 000 ml, fill to the
mark with water.
The solution is stable for several months if stored at 4 °C to 6 °C.
Sulfur stock solution of 1 000 mg/l is also readily available commercially, and may be used instead.
7.2 Apparatus
Common laboratory equipment and glassware, and in particular the following.
7.2.1 Analytical balance, capable of weighing to an accuracy of 0,1 mg.
7.2.2 Inductively coupled plasma optical emission spectrometer.
Inductively coupled plasma optical emission spectrometer (ICP-OES) with radial viewing of the plasma
and simultaneous measurement of emission signals.
For measuring sulfur at wavelengths below 190 nm, the optical system shall be evacuated or be filled or
continuously flushed with an inert gas as recommended by the instrument manufacturer to obtain high
and stable signal intensities.
The instrument shall be equipped with radial plasma as a minimum requirement; axial plasma is equally
acc
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