oSIST prEN 18253:2025

Soil improvers and growing media - Determination of total organic carbon by dry combustion

This document specifies a method for the determination of total organic carbon (TOC) in soil improvers and growing media containing more than 1 g carbon per kg of dry matter (0,1 %).
NOTE Samples with a low dry matter content can have an influence on the achievable limit of quantification as defined in the scope (i.e. 1 g carbon per kg of dry matter).

Bodenverbesserungsmittel und Kultursubstrate - Bestimmung von organischem Gesamtkohlenstoff durch trockene Verbrennung

Dieses Dokument legt ein Verfahren für die Bestimmung des gesamten organischen Kohlenstoffs(TOC, en: total organic carbon) in Bodenverbesserungsmitteln und Kultursubstraten fest, die mehr als 1g Kohlenstoff jekg Trockensubstanz (0,1%) enthalten.
ANMERKUNG Proben mit einem niedrigen Trockensubstanzgehalt können einen Einfluss auf die erreichbare Bestim
mungsgrenze, wie im Anwendungsbereich festgelegt (d.h. 1g Kohlenstoff jekg Trockensubstanz), haben.

Amendements du sol et supports de culture - Détermination du carbone organique total par combustion sèche

Le présent document spécifie une méthode pour la détermination du carbone organique total (COT) dans les amendements du sol et les supports de culture contenant plus de 1 g de carbone par kg de matière sèche (0,1 %).
NOTE Les échantillons à faible teneur en matière sèche peuvent avoir une influence sur la limite de quantification réalisable telle que définie dans le domaine d’application (c’est-à-dire 1 g de carbone par kg de matière sèche).

Izboljševalci tal in rastni substrati - Določanje celotnega organskega ogljika (TOC) s suhim sežigom

General Information

• Status: Not Published
• Public Enquiry End Date: 19-Dec-2025
• ICS: 65.080 - Fertilizers
• Technical Committee: KAT - Soil quality
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 17-Oct-2025
• Due Date: 06-Mar-2026
• Directive: 2003/2003 - Regulation (EC) N° 2003/2003 of the European Parlament and of the council of 13 October 2003 relating to fertilisers
• Directive: 2019/1009 - Regulation (EU) 2019/1009 of the European Parliament and of the Council of 5 June 2019 laying down rules on the making available on the market of EU fertilising products and amending Regulations (EC) No 1069/2009 and (EC) No 1107/2009 and repealing Regulation (EC) No 2003/2003
• Mandate: M/564 - Fertilising products in support of Regulation (EU) 2019/1009
• Mandate: M/564 AMD 1 - amending Implementing Decision C(2020) 612 as regards certain harmonised standards and standardisation deliverables, deadlines for their adoption and the duration of the validity of the standardisation request
• Mandate: M/564 AMD 2 - Commission Implementing decision amending Implementing Decision C(2020)612 as regards harmonised standards, the deadlines for the adoption of those standards and the duration of the validity of the standardisation request to the European Committee for Standardisation as regards the EU fertilising products in support of Regulation (EU) 2019/1009 of the European Parliament and of the Council
• Mandate: M/588 - COMMISSION IMPLEMENTING DECISION of 20.9.2022 on a standardisation request to the European Committee for Standardisation as regards methods for the measurements of emissions into the air of polychlorinated dibenzo-pdioxins and furans (PCDDs/PCDFs) and dioxin-like polychlorinated biphenyls (PCBs), total gaseous mercury and formaldehyde in support of Directive 2010/75/EU of the European Parliament and of the Council
• Mandate: M/XXX - COMMISSION IMPLEMENTING DECISION of XXX on a standardisation request to the European Committee for Standardization, to the European Committee for Electrotechnical Standardization and to the European Telecommunications Standards Institute as regards certain measuring instruments in support of Directive 2014/32/EU of the European Parliament and of the Council
• Ref Project: prEN 18253 - Soil improvers and growing media - Determination of total organic carbon by dry combustion

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2025
Izboljševalci tal in rastni substrati - Določanje celotnega organskega ogljika (TOC)
s suhim sežigom
Soil improvers and growing media - Determination of total organic carbon by dry
combustion
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung von organischem
Gesamtkohlenstoff durch trockene Verbrennung
Amendements du sol et supports de culture - Détermination du carbone organique total
par combustion sèche
Ta slovenski standard je istoveten z: prEN 18253
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 65.080
English Version
Soil improvers and growing media - Determination of total
organic carbon by dry combustion
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Détermination du carbone organique total par Bestimmung von organischem Gesamtkohlenstoff
combustion sèche durch trockene Verbrennung
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 223.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18253:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
4.1 Method A (direct method) . 4
4.2 Method B (indirect method) . 5
4.3 Interferences . 5
5 Reagents . 5
6 Apparatus . 6
7 Sampling . 6
8 Procedure . 6
8.1 Sample preparation . 6
8.2 Determination . 7
8.2.1 General. 7
8.2.2 Preparation of solid samples . 7
8.2.3 Preparation of liquid samples . 7
8.2.4 Method A: direct determination of the TOC . 7
8.2.5 Method B: indirect determination of TOC . 8
8.3 Calibration . 8
8.4 Control measurements . 9
9 Calculation and expression of results . 9
10 Test report . 11
11 Validation of the method . 11
11.1 Validation in accordance with ISO 5725-2. 11
11.2 Performance characteristics. 11
Annex A (informative) Example of operational information . 12
Annex B (informative) Performance characteristics of the method . 14
Bibliography . 16

European foreword
This document (prEN 18253:2025) has been prepared by Technical Committee CEN/TC 223 “Soil
improvers and growing media”, the secretariat of which is held by NEN.
This document is currently submitted to CEN Enquiry.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
1 Scope
This document specifies a method for the determination of total organic carbon (TOC) in soil improvers
and growing media containing more than 1 g carbon per kg of dry matter (0,1 %).
NOTE Samples with a low dry matter content can have an influence on the achievable limit of quantification as
defined in the scope (i.e. 1 g carbon per kg of dry matter).
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.
CEN/TS 17732:2022, Soil improvers and growing media - Terminology
EN 12579:2024, Soil improvers and growing media - Sampling
prEN 13040-1:2025, Soil improvers and growing media — Sample preparation — Part 1: Sample
preparation for chemical and physical tests, determination of dry matter content, moisture content and
laboratory bulk density
CEN/TS 17776:2022, Organic and organo-mineral fertilizers - Determination of the total organic carbon
(TOC) content by dry combustion
EN ISO 10693:2014, Soil quality - Determination of carbonate content - Volumetric method (ISO
10693:1995)
3 Terms and definitions
For the purposes of this document the terms and definitions given in CEN/TS 17732:2022 and the
following apply.
3.1
total carbon (TC)
quantity of carbon present in the sample in the form of organic, inorganic and elemental carbon
Note 1 to entry: In agreement with Regulation (EU) 2019/1009 [7], carbon derived from urea and polymers
containing urea are not considered as organic in this document.
[SOURCE: CEN/TS 17732:2022, 3.7.21 modified (note 1 to entry added)]
4 Principle
4.1 Method A (direct method)
The carbon dioxide released by the following combustion in an oxygen containing gas flow free of carbon
dioxide, is measured by infrared spectrometry, thermal conductivity detection, or by the detector
provided by the equipment used. To ensure complete combustion, catalysts and/or modifiers may be
used. The released amount of carbon dioxide indicates the TOC.
The carbonates present in the sample shall be previously removed by treating the sample with acid. The
carbon dioxide released by the following combustion step indicates the TOC directly.
Alternatively, the combustion temperature may be set at 600°C, thus only releasing organically bound
carbon.
4.2 Method B (indirect method)
TOC is obtained by the difference between the results of the measurements of total carbon and total
inorganic carbon (TIC). The total carbon (TC) present in the sample is converted into carbon dioxide by
combustion in an oxygen containing gas flow free of carbon dioxide. To ensure complete combustion,
catalysts and/or modifiers may be used. The released amount of carbon dioxide is measured e.g. by
infrared spectrometry, thermal conductivity detection, or other suitable techniques.
The TIC is determined separately from another sub-sample by means of acidification and purging of the
released carbon dioxide. The carbon dioxide shall be measured by one of the techniques mentioned
above.
4.3 Interferences
In the case of experience with samples containing high amounts of carbonates (e.g. carbonates to TOC
ratio higher than 10) the operator shall take care to correctly eliminate all the carbonates to make sure
to produce reliable TOC results.
When present, carbon from urea and urea-condensates carbides is determined as organic carbon using
the method described in this document. An interpretation of the measured value may therefore be
problematic in cases where the sample contains relevant levels of the above-mentioned components. If
needed, these components shall be determined separately by means of a suitable validated method and
be recorded in the test report.
5 Reagents
All reagents shall be of recognized analytical grade.
5.1 Potassium hydrogen phthalate, C8H5O4K.
H NO.
5.2 Acetanilide, C8 9
5.3 Atropine, C H NO .
17 23 3
5.4 Sodium salicylate, C H O Na.
7 5 3
5.5 Tetrasodium ethylenediamine tetraacetate-tetra-hydrate, Na
EDTA · 4H O (C H N O Na · 4H O), heated at 80 °C for 2 h.
2 10 12 2 8 4 2
Other forms of Na -EDTA hydrates may be used if the water content is exactly known. In these cases, the
composition of the control mixtures shall be recalculated accordingly (see also 5.8).
NOTE Other certified substances can be used as reference materials as well.
5.6 Aluminium oxide, Al O , neutral, granular size < 200 µm, annealed at 600 °C.
2 3
5.7 Calcium carbonate, CaCO .
5.8 Control mixture.
Control mixture prepared from sodium salicylate (5.4), calcium carbonate (5.7), Na -EDTA · 4H O (5.5)
4 2
and aluminium oxide (5.6) in a mass ratio of 1,00 : 4,36 : 1,97 : 8,40.
The mixture shall be homogenized thoroughly (e.g. fine grinding). It should contain 33,3 g/kg total
inorganic carbon and 66,6 g/kg TOC (e.g. 6,36 g of sodium salicylate, 27,73 g of calcium carbonate, 12,53 g
of Na -EDTA · 4H O, 53,42 g of aluminium oxide).
4 2
NOTE Other control mixtures can be used provided their suitability is checked.
®1
5.9 Inert absorbent material for determination on fluid samples, e.g. Chromosorb .
5.10 Non-oxidizing mineral acid used for carbon dioxide expulsion, e.g. phosphoric acid H PO
3 4
(w = 85 %).
NOTE Due to possible corrosion by hydrochloric acid, phosphoric acid is preferred.
5.11 Carrier gas, e.g. helium, oxygen or argon, free of carbon dioxide and organic impurities in
accordance with the manufacturer's instructions.
6 Apparatus
6.1. Precision balance, capable of weighing to the nearest 0,5 % of test portion mass.
6.2 Equipment for determination of carbon in solids, with accessories.
6.3 Crucibles, capsules or boats, made of e.g. silver, tin, ceramics or platinum.
Tin and nickel crucibles are not acid-resistant. In case of the necessity to remove inorganic carbon (8.2.4),
silver or ceramics vessels shall be used.
6.4 Pasteur pipettes.
6.5 Drying system, thermostatically controlled and capable of maintaining temperature of
105 °C ± 2 °C.
6.6 Desiccator, with an active drying agent such as silica gel.
6.7 Evapo
...