EN ISO 16720:2007

Soil quality - Pretreatment of samples by freeze-drying for subsequent analysis (ISO 16720:2005)

ISO 16720:2005 specifies a method for pretreatment of soil samples by freeze-drying for subsequent analysis.
ISO 16720:2005 is applicable to soil samples for subsequent determination of elements or organic compounds recognized as non-volatile under freeze-drying conditions. Generally, ISO 16720:2005 can also be applied to samples from sludges and sediments.
This method is also applicable as a first step for the determination of dry matter (or water) content, for instance in the case of samples with high water content.

Bodenbeschaffenheit - Vorbehandlung von Proben durch Gefriertrocknung für die anschließende Analyse (ISO 16720:2005)

Diese Internationale Norm legt ein Verfahren zur Vorbehandlung von Proben durch Gefriertrocknung für die anschließende Analyse fest.
Diese Internationale Norm ist für Proben aus Böden für die anschließende Bestimmung von Elementen oder organischen Verbindungen anwendbar, die unter den Bedingungen der Gefriertrocknung als nicht-flüchtig identifiziert werden. Grundsätzlich kann diese Internationale Norm auch für Schlamm- und Sedimentproben angewendet werden.
Die Gefriertrocknung kann als erster Schritt bei der Bestimmung des Trockenmasseanteiles (oder des Wassergehaltes) angewendet werden, beispielsweise im Falle von Proben mit einem hohen Wassergehalt.

Qualité du sol - Prétraitement des échantillons par lyophilisation pour analyse subséquente (ISO 16720:2005)

L'ISO 16720:2005 spécifie une méthode de prétraitement par lyophilisation d'échantillons destinés à être soumis à une analyse ultérieure.
L'ISO 16720:2005 est applicable à des échantillons de sols qui vont être ensuite soumis à un dosage d'éléments ou de composés organiques reconnus comme étant non volatils dans les conditions de lyophilisation. D'une façon générale, l'ISO 16720:2005 peut aussi être applicable à des échantillons de boues et de sédiments.
Cette méthode peut aussi être utilisée en tant que première étape pour déterminer la teneur en matière sèche (ou en eau), par exemple dans le cas d'échantillons ayant une teneur en eau élevée.

Kakovost tal - Priprava vzorcev za analizo z liofilizacijo (ISO 16720:2005)

General Information

• Status: Published
• Publication Date: 20-Mar-2007
• Withdrawal Date: 29-Sep-2007
• ICS: 13.080.20 - Physical properties of soils
• Technical Committee: CEN/TC 308 - Characterization of sludges
• Drafting Committee: CEN/TC 308/WG 1 - Characterization methods
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 21-Mar-2007
• Due Date: 18-Apr-2008
• Completion Date: 21-Mar-2007
• Ref Project: SIST EN ISO 16720:2007 - Soil quality - Pretreatment of samples by freeze-drying for subsequent analysis (ISO 16720:2005)

Overview

EN ISO 16720:2007, titled Soil Quality - Pretreatment of Samples by Freeze-Drying for Subsequent Analysis (ISO 16720:2005), is a European and international standard developed by CEN and ISO. This standard specifies a standardized method for pretreating soil samples through freeze-drying, preparing them for precise and reliable subsequent chemical or physical analyses. It applies to soil samples, as well as sludge and sediment samples, particularly for the determination of non-volatile elements or organic compounds. The method also serves as an initial step for measuring dry matter or water content in samples with high moisture levels.

Freeze-drying, also known as lyophilization, removes water content by sublimating ice under vacuum conditions, preserving the sample's integrity for later testing. EN ISO 16720:2007 ensures uniformity and reproducibility in sample preparation, a critical phase influencing the quality of analytical results.

Key Topics

• Scope and Applicability
  Applicable to soils, sludges, and sediments for the determination of elements or organic compounds resistant to freeze-drying temperatures. Suitable for samples with high water content requiring dry matter or water content determination.

• Freeze-Drying Principle
  Samples are pre-cooled below their eutectic points (generally below −40 °C) to freeze the material. Under vacuum, ice sublimates directly to vapor without passing through the liquid phase, ensuring sample constituents remain unchanged.

• Apparatus and Equipment

  • Freeze-drying chambers with temperature-controlled carriers or external inlet manifolds for sample flasks
  • Vacuum systems maintaining pressures between 37 Pa to 63 Pa to prevent thawing
  • Cooling condensers operated below −50 °C to capture sublimated water vapor
  • Pre-cooling freezers and rotating systems for even and rapid sample freezing
  • Appropriate sample containers ensuring sample thickness does not exceed 2 cm

• Procedure and Sample Handling
  Samples are placed in containers with a thin layer to accelerate freezing and drying. Post drying, samples become pulverulent and require careful handling to minimize dust formation and loss. Samples may be stored in airtight containers, such as brown glass bottles, to prevent moisture reabsorption.

• Dry Matter Content Determination
  The standard outlines calculations for partially dried samples and final dry matter content adjusted to standard drying at 105 °C, accounting for residual water absorbed during storage or handling.

• Interferences & Limitations
  Volatile compounds may partially vaporize and be lost during freeze-drying, potentially impacting certain analytical results. For example, ammonia nitrogen may not be stable under these conditions. Therefore, exclusion or adjustment in analyses involving volatile compounds is necessary.

• Documentation and Reporting
  Test reports must reference the standard, identify samples, document pretreatment, and note any deviations or influencing factors affecting results.

Applications

• Soil Quality Assessment
  Pretreatment of soil samples by freeze-drying facilitates accurate determination of elemental and organic constituents without alteration by heat or moisture.

• Environmental Monitoring
  Applicable to sludge and sediment samples for monitoring pollution levels, nutrient content, or contaminant characterization while preserving chemical stability.

• Agriculture and Land Management
  Freeze-dried soils are used to evaluate soil health parameters, nutrient status, and organic matter content critical for sustainable land use.

• Research and Laboratory Analysis
  Provides standardized sample preparation ensuring reproducibility in physicochemical analysis, supporting comparative studies and regulatory compliance.

• Water Content and Dry Matter Analysis
  Suitable as a preparatory method especially for samples with high moisture, enabling reliable subsequent gravimetric determinations.

Related Standards

• ISO 11464: Soil Quality - Pretreatment of Samples for Physico-Chemical Analyses
  Complements ISO 16720 by detailing methods for preparing soil samples prior to chemical analysis.

• ISO 11465: Soil Quality - Determination of Dry Matter and Water Content on a Mass Basis - Gravimetric Method
  Provides standardized gravimetric procedures to measure dry matter and moisture, which can follow freeze-drying pretreatment.

Conclusion

EN ISO 16720:2007 sets out a precise, reproducible method for freeze-drying soil, sludge, and sediment samples preparing them for various analytical determinations. Its method minimizes compound loss and degradation, crucially supporting accurate soil quality evaluations, environmental analyses, and research. Laboratories and environmental agencies adopting this standard benefit from internationally harmonized procedures enhancing data reliability and comparability.

Keywords: soil quality, freeze-drying, sample pretreatment, lyophilization, soil analysis, sludge analysis, sediment pretreatment, dry matter content, water content determination, ISO 16720, CEN standards.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2007
Kakovost tal - Priprava vzorcev za analizo z liofilizacijo
Soil quality - Pretreatment of samples by freeze-drying for subsequent analysis (ISO
16720:2005)
Bodenbeschaffenheit - Vorbehandlung von Proben durch Gefriertrocknung für die
anschließende Analyse (ISO 16720:2005)
Qualité du sol - Prétraitement des échantillons par lyophilisation pour analyse
subséquente (ISO 16720:2005)
Ta slovenski standard je istoveten z: EN ISO 16720:2007
ICS:
13.080.20 Fizikalne lastnosti tal Physical properties of soils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16720
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2007
ICS 13.080.20
English Version
Soil quality - Pretreatment of samples by freeze-drying for
subsequent analysis (ISO 16720:2005)
Qualité du sol - Prétraitement des échantillons par Bodenbeschaffenheit - Vorbehandlung von Proben durch
lyophilisation pour analyse subséquente (ISO 16720:2005) Gefriertrocknung für die anschließende Analyse (ISO
16720:2005)
This European Standard was approved by CEN on 25 February 2007.
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 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 Management Centre has the same status as the
official versions.
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. EN ISO 16720:2007: E
worldwide for CEN national Members.

Foreword
The text of ISO 16720:2005 has been prepared by Technical Committee ISO/TC 190 "Soil
quality” of the International Organization for Standardization (ISO) and has been taken over as
secretariat of which is held by AFNOR.

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 September 2007, and conflicting national
standards shall be withdrawn at the latest by September 2007.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: 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.
Endorsement notice
The text of ISO 16720:2005 has been approved by CEN as EN ISO 16720:2007 without any
modifications.
INTERNATIONAL ISO
STANDARD 16720
First edition
2005-03-15
Soil quality — Pretreatment of samples
by freeze-drying for subsequent analysis
Qualité du sol — Prétraitement des échantillons par lyophilisation pour
analyse subséquente
Reference number
ISO 16720:2005(E)
©
ISO 2005
ISO 16720:2005(E)
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ISO 16720:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16720 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical
methods and soil characteristics.

INTERNATIONAL STANDARD ISO 16720:2005(E)

Soil quality — Pretreatment of samples by freeze-drying
for subsequent analysis
1 Scope
This International Standard specifies a method for pretreatment of soil samples by freeze-drying for
subsequent analysis.
This International Standard is applicable to soil samples for subsequent determination of elements or organic
compounds recognized as non-volatile under freeze-drying conditions. Generally, this International Standard
can also be applied to samples from sludges and sediments.
This method is also applicable as a first step for the determination of dry matter (or water) content, for
instance in the case of samples with high water content.
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.
ISO 11464, Soil quality — Pretreatment of samples for physico-chemical analyses
ISO 11465, Soil quality — Determination of dry matter and water content on a mass basis — Gravimetric
method
3 Principle and general requirements
Before freeze-drying, samples shall be cooled below their eutectic points. These are rarely known, but
freezing the samples below −40 °C is usually sufficient.
During freeze-drying, water is removed from the sample under vacuum conditions by direct conversion from
ice to vapour (sublimation) which is collected in a condenser where it releases its heat energy and turns again
into ice. Generally a temperature below −50 °C inside the condenser is suitable for usual applications.
Sublimation requires heat in order to take place within an acceptable range of time. When the frozen sample
containers are connected to an external inlet manifold (see 5.1.2), heat energy is supplied by the laboratory
atmosphere. In case of a drying chamber equipped with temperature-controlled carriers (see 5.1.1), this
energy is provided by heating the carriers.
Vacuum conditions shall allow the generation of vapour pressure difference needed for sublimation and the
continuous evacuation of water vapour from the sample. Throughout the drying process, the pressure inside
the apparatus and the temperature of the sample(s) shall be such as to avoid sample thawing and loss of any
compound of interest. This last point may be difficult to achieve due to the large range of possible energy
levels of the bonds between compounds of interest and the solid phase. For compounds known as
non-volatile, a final temperature of the sample between −20 °C to −25 °C is suitable. Other final temperature
...