Soil quality - Microwave-assisted extraction of the aqua regia soluble fraction for the determination of elements

This International Standard specifies a method for microwave-assisted extraction of elements from samples
using aqua regia as the extraction solution for the determination of elements. This method is applicable to all
types of soil and soil material.
Aqua regia extraction is suitable for the release of trace and major element fractions in soil. Aqua regia is not
suitable for the extraction of elements from refractory compounds, such as SiO2, TiO2 and Al2O3.
The extraction with aqua regia is operationally defined and will not necessarily release all elements completely.
The microwave method is generic and can be implemented using a wide variety of equipment, provided:
a) the extraction mixture ratio is unchanged;
b) the extraction temperature is known.
Solutions produced by the microwave method are suitable for analysis, for example, by using atomic
absorption spectrometry (flame: FAAS, hydride generation: HGAAS, cold vapour: CVAAS, graphite furnace;
GFAAS), inductively coupled plasma emission spectrometry (ICP/OES) and inductively coupled plasma mass
spectrometry (ICP/MS).
NOTE Due to the presence of chloride in the extraction solution, limitations for the application of analytical
techniques can occur.

Qualité du sol - Extraction assistée par micro-ondes de la fraction soluble dans l'eau régale pour la détermination des éléments

L'ISO 12914:2012 sp�cifie une m�thode d'extraction assist�e par micro-ondes d'�l�ments d'�chantillons en utilisant l'eau r�gale comme solution d'extraction pour la d�termination des �l�ments. La m�thode s'applique � tous les types de sols et de mat�riaux du sol.

Kakovost tal - Določevanje elementov v frakciji, topni v zlatotopki, po ekstrakciji z mikrovalovi

Ta mednarodni standard določa metodo za ekstrakcijo elementov z mikrovalovi iz vzorcev v zlatotopki kot ekstrakcijski raztopini za določevanje elementov. Ta metoda se uporablja za vse vrste vzorcev tal in talnih materialov.
Ekstrakcija z zlatotopko je primerna za sproščanje elementov v sledovih in večjih frakcijah v tleh. Zlatotopka ni primerna za ekstrakcijo elementov iz ognjevzdržnih zmesi, kot so SiO2, TiO2 in Al2O3. Ekstrakcija z zlatotopko je opredeljena operativno in se z njo ne bodo nujno popolnoma sprostili vsi elementi.
Mikrovalovna metoda je splošna metoda in jo je mogoče izvajati z najrazličnejšo opremo, če je:
a) razmerje mešanice ekstrakcije nespremenjeno;
b) temperatura ekstrakcije znana.
Raztopine, pridobljene z mikrovalovno metodo, so primerne za analizo, na primer z atomsko absorpcijsko spektrometrijo (plamen: FAAS, tvorba hidridov: HGAAS, hladna para: CVAAS, grafitna kiveta:
GFAAS), emisijsko spektrometrijo z induktivno sklopljeno plazmo (ICP-OES) in masno spektrometrijo z induktivno sklopljeno plazmo (ICP-MS).
OPOMBA: Zaradi prisotnosti klorida v ekstrakcijski raztopini se lahko pojavijo omejitve pri uporabi analiznih tehnik.

General Information

Status
Published
Public Enquiry End Date
03-Jun-2019
Publication Date
03-Sep-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
30-Aug-2019
Due Date
04-Nov-2019
Completion Date
04-Sep-2019

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INTERNATIONAL ISO
STANDARD 12914
First edition
2012-02-01
Soil quality — Microwave-assisted
extraction of the aqua regia soluble
fraction for the determination of elements
Qualité du sol — Extraction assistée par micro-ondes de la fraction
soluble dans l’eau régale pour la détermination des éléments
Reference number
ISO 12914:2012(E)
ISO 2012
---------------------- Page: 1 ----------------------
ISO 12914:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s

member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 12914:2012(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 12914 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical

methods and soil characteristics.
© ISO 2012 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 12914:2012(E)
Introduction

This International Standard is a module for analysis of inorganic parameters in soil and soil material. This

International Standard concerns the extraction with aqua regia for the subsequent analysis of elements.

Aqua regia will not totally dissolve most soils and similar materials, and the efficiency of the extraction for

particular elements differs from element to element. Such efficiency might also differ for the same element in

different matrices. Users of this International Standard should carry out a program of analysis using reference

materials to ensure that the method given here is appropriate for their needs. Elements extractable in aqua

regia cannot, therefore, be regarded as ‘totals’; conversely, they cannot be regarded as the ‘bio available’

fraction, as the extraction procedure is too vigorous to represent any biological process.

iv © ISO 2012 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 12914:2012(E)
Soil quality — Microwave-assisted extraction of the aqua regia
soluble fraction for the determination of elements
1 Scope

This International Standard specifies a method for microwave-assisted extraction of elements from samples

using aqua regia as the extraction solution for the determination of elements. This method is applicable to all

types of soil and soil material.

Aqua regia extraction is suitable for the release of trace and major element fractions in soil. Aqua regia is not

suitable for the extraction of elements from refractory compounds, such as SiO , TiO and Al O .

2 2 2 3

The extraction with aqua regia is operationally defined and will not necessarily release all elements completely.

The microwave method is generic and can be implemented using a wide variety of equipment, provided:

a) the extraction mixture ratio is unchanged;
b) the extraction temperature is known.

Solutions produced by the microwave method are suitable for analysis, for example, by using atomic

absorption spectrometry (flame: FAAS, hydride generation: HGAAS, cold vapour: CVAAS, graphite furnace;

GFAAS), inductively coupled plasma emission spectrometry (ICP/OES) and inductively coupled plasma mass

spectrometry (ICP/MS).

NOTE Due to the presence of chloride in the extraction solution, limitations for the application of analytical

techniques can occur.
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 3696, Water for analytical laboratory use — Specification and test methods

ISO 10381-1, Soil quality — Sampling — Part 1: Guidance on the design of sampling programmes

ISO 11464, Soil quality — Pretreatment of samples for physico-chemical analysis

ISO 11465:1993, Soil quality — Determination of dry matter and water content on a mass base —

Gravimetric method

ISO 18512, Soil quality — Guidance on long and short term storage of soil samples

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aqua regia

extraction solution obtained by mixing 1 volume of nitric acid, w(HNO ) = 65 % to 70 %, and 3 volumes of

hydrochloric acid, w(HCl) = 35 % to 37 %
© ISO 2012 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 12914:2012(E)
3.2
extraction

mineralization of the organic matter of a sample and dissolution of its mineral part, more or less completely,

when reacting with the reagent mixture
3.3
sample
portion of soil material selected from a larger quantity of material
[ISO 11074:2005]
3.4
laboratory sample
sample intended for laboratory inspection of testing
[ISO 11074:2005]
3.5
test sample

portion of material resulting from the laboratory sample by means of an appropriate method of sample

pretreatment and having the size (volume/mass) necessary for the desired testing or analysis

[ISO 11074:2005]
3.6
test portion;
analytical portion

quantity of material, of proper size, for measurement of the concentration or other property of interest removed

from the test sample

NOTE 1 The test portion may be taken from the primary sample or from the laboratory sample directly if no preparation

of sample is required (e.g. with liquids), but usually it is taken from the prepared test sample.

NOTE 2 A unit or increment of proper homogeneity, size and fineness, needing no further preparation, may be a test portion.

[ISO 11074:2005]
3.7
dry matter

mass fraction of a sample weight after the specified drying process and the weight of the moist sample

NOTE It is expressed in percent.
[ISO 11465:1993]
4 Safety remarks
All of the work has to be performed by trained persons.

The reagents used within this International Standard are strongly corrosive and potentially very

harmful. Safety precautions are absolutely necessary due to toxic fumes and strong corrosive

reagents, high temperature and high pressure.

All procedures have to be performed in a hood or in closed force-ventilated equipment. By the use

of strong oxidizing reagents, the formation of explosive organic intermediates is possible, especially

when dealing with samples with a high organic content. Do not open pressurized vessels before they

have cooled down. Avoid contact with the chemicals and the gaseous reaction products.

2 © ISO 2012 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 12914:2012(E)
5 Principle

The laboratory sample should be treated in accordance with the principles of ISO 11464, in order to produce

a homogeneous test sample from which a test portion can be subsampled and digested by aqua regia to the

following heating procedure.

Microwave extraction at 175 °C ± 5 °C for 10 min ± 1 min in a closed vessel, followed by filtration and adjustment

of the volume in a volumetric flask.
6 Interferences and sources of errors

Due to the volatility of some compounds, it is important to take care that the sample is not heated before the

extraction, and that the volatile reaction products which might be formed during the extraction are not allowed

to escape. Grinding or milling samples includes a risk of contamination of the sample by the environment (e. g.

air, dust, wear of milling equipment). Losses of volatile compounds are possible due to elevated temperatures

(e.g. a drying temperature over 40 °C may result in losses of mercury).

During trace-element determinations, contaminations shall be avoided. The container in which the sample is

delivered and stored can be a source of errors. The container’s material shall be chosen such that it does not

absorb the elements to be determined (e.g. elemental Hg can penetrate polyethylene walls very fast in both

directions and glass can contaminate samples with its constituent elements such as B, Na, K, Al).

For the determination of elements forming volatile compounds (e.g. Hg, As), special care has to be taken during

sample pretreatment.

The use of the described extraction procedures may leave large parts of the sample undissolved.

High-acid and high-dissolved-matrix concentrations in the extract may cause interferences in measurement steps.

Depending on the concentration of the elements of interest, particular attention needs to be paid to the cleaning

of the laboratory equipment. It is recommended to thoroughly clean all laboratory equipment and, as a minimum,

leave the equipment standing overnight in 1 % to 5 % nitric acid.

Care shall be taken to ensure that the test portion is in contact with the acid mixture in the reaction vessel. Boiling

...

SLOVENSKI STANDARD
SIST ISO 12914:2019
01-oktober-2019

Kakovost tal - Določevanje elementov v frakciji, topni v zlatotopki, po ekstrakciji z

mikrovalovi

Soil quality - Microwave-assisted extraction of the aqua regia soluble fraction for the

determination of elements

Qualité du sol - Extraction assistée par micro-ondes de la fraction soluble dans l'eau

régale pour la détermination des éléments
Ta slovenski standard je istoveten z: ISO 12914:2012
ICS:
13.080.10 Kemijske značilnosti tal Chemical characteristics of
soils
SIST ISO 12914:2019 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 12914:2019
---------------------- Page: 2 ----------------------
SIST ISO 12914:2019
INTERNATIONAL ISO
STANDARD 12914
First edition
2012-02-01
Soil quality — Microwave-assisted
extraction of the aqua regia soluble
fraction for the determination of elements
Qualité du sol — Extraction assistée par micro-ondes de la fraction
soluble dans l’eau régale pour la détermination des éléments
Reference number
ISO 12914:2012(E)
ISO 2012
---------------------- Page: 3 ----------------------
SIST ISO 12914:2019
ISO 12914:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s

member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 12914:2019
ISO 12914:2012(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 12914 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical

methods and soil characteristics.
© ISO 2012 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 12914:2019
ISO 12914:2012(E)
Introduction

This International Standard is a module for analysis of inorganic parameters in soil and soil material. This

International Standard concerns the extraction with aqua regia for the subsequent analysis of elements.

Aqua regia will not totally dissolve most soils and similar materials, and the efficiency of the extraction for

particular elements differs from element to element. Such efficiency might also differ for the same element in

different matrices. Users of this International Standard should carry out a program of analysis using reference

materials to ensure that the method given here is appropriate for their needs. Elements extractable in aqua

regia cannot, therefore, be regarded as ‘totals’; conversely, they cannot be regarded as the ‘bio available’

fraction, as the extraction procedure is too vigorous to represent any biological process.

iv © ISO 2012 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 12914:2019
INTERNATIONAL STANDARD ISO 12914:2012(E)
Soil quality — Microwave-assisted extraction of the aqua regia
soluble fraction for the determination of elements
1 Scope

This International Standard specifies a method for microwave-assisted extraction of elements from samples

using aqua regia as the extraction solution for the determination of elements. This method is applicable to all

types of soil and soil material.

Aqua regia extraction is suitable for the release of trace and major element fractions in soil. Aqua regia is not

suitable for the extraction of elements from refractory compounds, such as SiO , TiO and Al O .

2 2 2 3

The extraction with aqua regia is operationally defined and will not necessarily release all elements completely.

The microwave method is generic and can be implemented using a wide variety of equipment, provided:

a) the extraction mixture ratio is unchanged;
b) the extraction temperature is known.

Solutions produced by the microwave method are suitable for analysis, for example, by using atomic

absorption spectrometry (flame: FAAS, hydride generation: HGAAS, cold vapour: CVAAS, graphite furnace;

GFAAS), inductively coupled plasma emission spectrometry (ICP/OES) and inductively coupled plasma mass

spectrometry (ICP/MS).

NOTE Due to the presence of chloride in the extraction solution, limitations for the application of analytical

techniques can occur.
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 3696, Water for analytical laboratory use — Specification and test methods

ISO 10381-1, Soil quality — Sampling — Part 1: Guidance on the design of sampling programmes

ISO 11464, Soil quality — Pretreatment of samples for physico-chemical analysis

ISO 11465:1993, Soil quality — Determination of dry matter and water content on a mass base —

Gravimetric method

ISO 18512, Soil quality — Guidance on long and short term storage of soil samples

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aqua regia

extraction solution obtained by mixing 1 volume of nitric acid, w(HNO ) = 65 % to 70 %, and 3 volumes of

hydrochloric acid, w(HCl) = 35 % to 37 %
© ISO 2012 – All rights reserved 1
---------------------- Page: 7 ----------------------
SIST ISO 12914:2019
ISO 12914:2012(E)
3.2
extraction

mineralization of the organic matter of a sample and dissolution of its mineral part, more or less completely,

when reacting with the reagent mixture
3.3
sample
portion of soil material selected from a larger quantity of material
[ISO 11074:2005]
3.4
laboratory sample
sample intended for laboratory inspection of testing
[ISO 11074:2005]
3.5
test sample

portion of material resulting from the laboratory sample by means of an appropriate method of sample

pretreatment and having the size (volume/mass) necessary for the desired testing or analysis

[ISO 11074:2005]
3.6
test portion;
analytical portion

quantity of material, of proper size, for measurement of the concentration or other property of interest removed

from the test sample

NOTE 1 The test portion may be taken from the primary sample or from the laboratory sample directly if no preparation

of sample is required (e.g. with liquids), but usually it is taken from the prepared test sample.

NOTE 2 A unit or increment of proper homogeneity, size and fineness, needing no further preparation, may be a test portion.

[ISO 11074:2005]
3.7
dry matter

mass fraction of a sample weight after the specified drying process and the weight of the moist sample

NOTE It is expressed in percent.
[ISO 11465:1993]
4 Safety remarks
All of the work has to be performed by trained persons.

The reagents used within this International Standard are strongly corrosive and potentially very

harmful. Safety precautions are absolutely necessary due to toxic fumes and strong corrosive

reagents, high temperature and high pressure.

All procedures have to be performed in a hood or in closed force-ventilated equipment. By the use

of strong oxidizing reagents, the formation of explosive organic intermediates is possible, especially

when dealing with samples with a high organic content. Do not open pressurized vessels before they

have cooled down. Avoid contact with the chemicals and the gaseous reaction products.

2 © ISO 2012 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 12914:2019
ISO 12914:2012(E)
5 Principle

The laboratory sample should be treated in accordance with the principles of ISO 11464, in order to produce

a homogeneous test sample from which a test portion can be subsampled and digested by aqua regia to the

following heating procedure.

Microwave extraction at 175 °C ± 5 °C for 10 min ± 1 min in a closed vessel, followed by filtration and adjustment

of the volume in a volumetric flask.
6 Interferences and sources of errors

Due to the volatility of some compounds, it is important to take care that the sample is not heated before the

extraction, and that the volatile reaction products which might be formed during the extraction are not allowed

to escape. Grinding or milling samples includes a risk of contamination of the sample by the environment (e. g.

air, dust, wear of milling equipment). Losses of volatile compounds are possible due to elevated temperatures

(e.g. a drying temperature over 40 °C may result in losses of mercury).

During trace-element determinations, contaminations shall be avoided. The container in which the sample is

delivered and stored can be a source of errors. The container’s material shall be chosen such that it does not

absorb the elements to be determined (e.g. elemental Hg can penetrate polyethylene walls very fast in both

directions and glass can contaminate samples with its constituent elements such as B, Na, K, Al).

For the determination of elements forming volatile compounds (e.g. Hg, As), special care has to be taken during

sample pretreatment.

The use of the described extraction procedures may leave large parts of the sample undissolved.

High-acid and high-dissolved-matrix concentrations in the extract may cause interferences in measurem

...

SLOVENSKI STANDARD
oSIST ISO 12914:2019
01-maj-2019

.DNRYRVWWDO'RORþHYDQMHHOHPHQWRYYIUDNFLMLWRSQLY]ODWRWRSNLSRHNVWUDNFLML]

PLNURYDORYL

Soil quality - Microwave-assisted extraction of the aqua regia soluble fraction for the

determination of elements

Qualité du sol - Extraction assistée par micro-ondes de la fraction soluble dans l'eau

régale pour la détermination des éléments
Ta slovenski standard je istoveten z: ISO 12914:2012
ICS:
13.080.10 .HPLMVNH]QDþLOQRVWLWDO Chemical characteristics of
soils
oSIST ISO 12914:2019 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST ISO 12914:2019
---------------------- Page: 2 ----------------------
oSIST ISO 12914:2019
INTERNATIONAL ISO
STANDARD 12914
First edition
2012-02-01
Soil quality — Microwave-assisted
extraction of the aqua regia soluble
fraction for the determination of elements
Qualité du sol — Extraction assistée par micro-ondes de la fraction
soluble dans l’eau régale pour la détermination des éléments
Reference number
ISO 12914:2012(E)
ISO 2012
---------------------- Page: 3 ----------------------
oSIST ISO 12914:2019
ISO 12914:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s

member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 12914:2019
ISO 12914:2012(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 12914 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical

methods and soil characteristics.
© ISO 2012 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST ISO 12914:2019
ISO 12914:2012(E)
Introduction

This International Standard is a module for analysis of inorganic parameters in soil and soil material. This

International Standard concerns the extraction with aqua regia for the subsequent analysis of elements.

Aqua regia will not totally dissolve most soils and similar materials, and the efficiency of the extraction for

particular elements differs from element to element. Such efficiency might also differ for the same element in

different matrices. Users of this International Standard should carry out a program of analysis using reference

materials to ensure that the method given here is appropriate for their needs. Elements extractable in aqua

regia cannot, therefore, be regarded as ‘totals’; conversely, they cannot be regarded as the ‘bio available’

fraction, as the extraction procedure is too vigorous to represent any biological process.

iv © ISO 2012 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST ISO 12914:2019
INTERNATIONAL STANDARD ISO 12914:2012(E)
Soil quality — Microwave-assisted extraction of the aqua regia
soluble fraction for the determination of elements
1 Scope

This International Standard specifies a method for microwave-assisted extraction of elements from samples

using aqua regia as the extraction solution for the determination of elements. This method is applicable to all

types of soil and soil material.

Aqua regia extraction is suitable for the release of trace and major element fractions in soil. Aqua regia is not

suitable for the extraction of elements from refractory compounds, such as SiO , TiO and Al O .

2 2 2 3

The extraction with aqua regia is operationally defined and will not necessarily release all elements completely.

The microwave method is generic and can be implemented using a wide variety of equipment, provided:

a) the extraction mixture ratio is unchanged;
b) the extraction temperature is known.

Solutions produced by the microwave method are suitable for analysis, for example, by using atomic

absorption spectrometry (flame: FAAS, hydride generation: HGAAS, cold vapour: CVAAS, graphite furnace;

GFAAS), inductively coupled plasma emission spectrometry (ICP/OES) and inductively coupled plasma mass

spectrometry (ICP/MS).

NOTE Due to the presence of chloride in the extraction solution, limitations for the application of analytical

techniques can occur.
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 3696, Water for analytical laboratory use — Specification and test methods

ISO 10381-1, Soil quality — Sampling — Part 1: Guidance on the design of sampling programmes

ISO 11464, Soil quality — Pretreatment of samples for physico-chemical analysis

ISO 11465:1993, Soil quality — Determination of dry matter and water content on a mass base —

Gravimetric method

ISO 18512, Soil quality — Guidance on long and short term storage of soil samples

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aqua regia

extraction solution obtained by mixing 1 volume of nitric acid, w(HNO ) = 65 % to 70 %, and 3 volumes of

hydrochloric acid, w(HCl) = 35 % to 37 %
© ISO 2012 – All rights reserved 1
---------------------- Page: 7 ----------------------
oSIST ISO 12914:2019
ISO 12914:2012(E)
3.2
extraction

mineralization of the organic matter of a sample and dissolution of its mineral part, more or less completely,

when reacting with the reagent mixture
3.3
sample
portion of soil material selected from a larger quantity of material
[ISO 11074:2005]
3.4
laboratory sample
sample intended for laboratory inspection of testing
[ISO 11074:2005]
3.5
test sample

portion of material resulting from the laboratory sample by means of an appropriate method of sample

pretreatment and having the size (volume/mass) necessary for the desired testing or analysis

[ISO 11074:2005]
3.6
test portion;
analytical portion

quantity of material, of proper size, for measurement of the concentration or other property of interest removed

from the test sample

NOTE 1 The test portion may be taken from the primary sample or from the laboratory sample directly if no preparation

of sample is required (e.g. with liquids), but usually it is taken from the prepared test sample.

NOTE 2 A unit or increment of proper homogeneity, size and nfi eness, needing no further preparation, may be a test portion.

[ISO 11074:2005]
3.7
dry matter

mass fraction of a sample weight after the specified drying process and the weight of the moist sample

NOTE It is expressed in percent.
[ISO 11465:1993]
4 Safety remarks
All of the work has to be performed by trained persons.

The reagents used within this International Standard are strongly corrosive and potentially very

harmful. Safety precautions are absolutely necessary due to toxic fumes and strong corrosive

reagents, high temperature and high pressure.

All procedures have to be performed in a hood or in closed force-ventilated equipment. By the use

of strong oxidizing reagents, the formation of explosive organic intermediates is possible, especially

when dealing with samples with a high organic content. Do not open pressurized vessels before they

have cooled down. Avoid contact with the chemicals and the gaseous reaction products.

2 © ISO 2012 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST ISO 12914:2019
ISO 12914:2012(E)
5 Principle

The laboratory sample should be treated in accordance with the principles of ISO 11464, in order to produce

a homogeneous test sample from which a test portion can be subsampled and digested by aqua regia to the

following heating procedure.

Microwave extraction at 175 °C ± 5 °C for 10 min ± 1 min in a closed vessel, followed by filtration and adjustment

of the volume in a volumetric flask.
6 Interferences and sources of errors

Due to the volatility of some compounds, it is important to take care that the sample is not heated before the

extraction, and that the volatile reaction products which might be formed during the extraction are not allowed

to escape. Grinding or milling samples includes a risk of contamination of the sample by the environment (e. g.

air, dust, wear of milling equipment). Losses of volatile compounds are possible due to elevated temperatures

(e.g. a drying temperature over 40 °C may result in losses of mercury).

During trace-element determinations, contaminations shall be avoided. The container in which the sample is

delivered and stored can be a source of errors. The container’s material shall be chosen such that it does not

absorb the elements to be determined (e.g. elemental Hg can penetrate polyethylene walls very fast in both

directions and glass can contaminate samples with its constituent elements such as B, Na, K, Al).

For the determination of elements forming volatile compounds (e.g. Hg, As), special care has to be taken during

sample pretreatment.

The use of the described extraction procedures may leave large parts of the sample undissolved.

High-acid and high-dissolved-matrix concentrations in the extract may cause interferences in measur

...

NORME ISO
INTERNATIONALE 12914
Première édition
2012-02-01
Qualité du sol — Extraction assistée par
micro-ondes de la fraction soluble dans
l’eau régale pour la détermination des
éléments
Soil quality — Microwave-assisted extraction of the aqua regia soluble
fraction for the determination of elements
Numéro de référence
ISO 12914:2012(F)
ISO 2012
---------------------- Page: 1 ----------------------
ISO 12914:2012(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2012

Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous

quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l’accord écrit

de l’ISO à l’adresse ci-après ou du comité membre de l’ISO dans le pays du demandeur.

ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Publié en Suisse
ii © ISO 2012 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 12914:2012(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes nationaux de

normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est en général confiée aux

comités techniques de l’ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du comité

technique créé à cet effet. Les organisations internationales, gouvernementales et non gouvernementales,

en liaison avec l’ISO participent également aux travaux. L’ISO collabore étroitement avec la Commission

électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.

Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI, Partie 2.

La tâche principale des comités techniques est d’élaborer les Normes internationales. Les projets de Normes

internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur publication

comme Normes internationales requiert l’approbation de 75 % au moins des comités membres votants.

L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de droits

de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable de ne pas avoir

identifié de tels droits de propriété et averti de leur existence.

L’ISO 12914 a été élaborée par le comité technique ISO/TC 190, Qualité du sol, sous-comité SC 3, Méthodes

chimiques et caractéristiques du sol.
© ISO 2012 – Tous droits réservés iii
---------------------- Page: 3 ----------------------
ISO 12914:2012(F)
Introduction

La présente Norme internationale est un module pour l’analyse des paramètres inorganiques dans le sol et les

matériaux du sol. La présente Norme internationale concerne l’extraction avec de l’eau régale pour l’analyse

ultérieure des éléments.

L’eau régale ne dissoudra pas totalement la plupart des sols et des matériaux du sol et l’efficacité d’extraction

des éléments particuliers diffère d’un élément à l’autre. Une telle efficacité peut également différer pour

un même élément présent dans différentes matrices. Il convient que les utilisateurs de la présente Norme

internationale exécutent un programme d’analyse à l’aide de matériaux de référence pour s’assurer que la

méthode mentionnée ici répond à leurs besoins. Par conséquent, les éléments extractibles dans l’eau régale

ne peuvent pas être considérés comme «totaux»; en revanche, ils ne peuvent pas être considérés comme

étant la fraction «biodisponible» car le mode opératoire d’extraction est trop énergique pour représenter un

procédé biologique.
iv © ISO 2012 – Tous droits réservés
---------------------- Page: 4 ----------------------
NORME INTERNATIONALE ISO 12914:2012(F)
Qualité du sol — Extraction assistée par micro-ondes de la fraction
soluble dans l’eau régale pour la détermination des éléments
1 Domaine d’application

La présente Norme internationale spécifie une méthode d’extraction assistée par micro-ondes d’éléments

d’échantillons en utilisant l’eau régale comme solution d’extraction pour la détermination des éléments. La

méthode s’applique à tous les types de sols et de matériaux du sol.

L’extraction dans l’eau régale convient à la libération des fractions d’éléments traces et majeurs dans le sol.

L’eau régale n’est pas appropriée à l’extraction des éléments provenant de composés réfractaires tels que

SiO , TiO et Al O .
2 2 2 3

L’extraction avec de l’eau régale est définie d’un point de vue opérationnel et ne permettra pas nécessairement

de libérer tous les éléments de manière complète.

La méthode reposant sur l’utilisation de micro-ondes est générique et peut être mise en place à l’aide de

plusieurs appareils, à condition que:
a) le rapport du mélange d’extraction demeure inchangé;
b) la température d’extraction soit connue.

Les solutions produites par la méthode reposant sur l’utilisation de micro-ondes conviennent à l’analyse, par

exemple en utilisant la spectrométrie d’absorption atomique (flamme: FAAS, génération d’hydrure: HGAAS,

vapeur froide: CVAAS, four à graphite: GFAAS), la spectrométrie d’émission avec plasma à couplage inductif

(ICP/OES) et la spectrométrie de masse avec plasma à couplage inductif (ICP/MS).

NOTE En raison de la présence de chlorure dans la solution d’extraction, il peut exister des limitations concernant

l’application des techniques d’analyse.
2 Références normatives

Les documents de référence suivants sont indispensables pour l’application du présent document. Pour les

références datées, seule l’édition citée s’applique. Pour les références non datées, la dernière édition du

document de référence s’applique (y compris les éventuels amendements).

ISO 3696, Eau pour laboratoire à usage analytique — Spécification et méthodes d’essai

ISO 10381-1, Qualité du sol — Échantillonnage — Partie 1: Lignes directrices pour l’établissement des

programmes d’échantillonnage

ISO 11464, Qualité du sol — Prétraitement des échantillons pour analyses physico-chimiques

ISO 11465:1993, Qualité du sol — Détermination de la teneur pondérale en matière sèche et en eau — Méthode

gravimétrique

ISO 18512, Qualité du sol — Lignes directrices relatives au stockage des échantillons de sol à long et à court termes

3 Termes et définitions

Pour les besoins du présent document, les termes et définitions suivants s’appliquent.

© ISO 2012 – Tous droits réservés 1
---------------------- Page: 5 ----------------------
ISO 12914:2012(F)
3.1
eau régale

solution d’extraction obtenue en mélangeant 1 volume d’acide nitrique, w(HNO ) = 65 % à 70 % et 3 volumes

d’acide chlorhydrique, w(HCl) = 35 % à 37 %
3.2
extraction

minéralisation de la matière organique d’un échantillon et dissolution de sa partie minérale, plus ou moins

complètement, lors de sa réaction avec le mélange réactionnel
3.3
échantillon
partie de matériaux du sol choisie dans une quantité de matériaux plus grande
[ISO 11074:2005]
3.4
échantillon pour laboratoire

échantillon destiné à être utilisé pour un contrôle ou pour des essais en laboratoire

[ISO 11074:2005]
3.5
échantillon pour essai

prise de matériau, issue de l’échantillon pour laboratoire, au moyen d’une méthode appropriée de traitement

préalable des échantillons, et ayant la taille (volume/masse) nécessaire pour les essais ou l’analyse souhaités

[ISO 11074:2005]
3.6
prise d’essai
fraction analytique

quantité de matériau, issue de l’échantillon pour essai, de taille appropriée, nécessaire à la détermination de

la concentration ou d’autres propriétés d’intérêt

NOTE 1 La prise d’essai peut être directement prélevée de l’échantillon primaire ou de l’échantillon pour laboratoire

si aucune préparation de l’échantillon n’est requise (par exemple, utilisation de liquides). Toutefois, elle est généralement

prélevée de l’échantillon pour essai préparé.

NOTE 2 On peut considérer comme prise d’essai une unité ou un prélèvement élémentaire suffisamment homogène,

de taille et de finesse adéquates, et ne nécessitant aucune préparation supplémentaire.

[ISO 11074:2005]
3.7
matière sèche

fraction massique du résidu sec d’un échantillon, après séchage effectué selon le procédé spécifié

NOTE Elle est exprimée en pourcentage.
[ISO 11465:1993]
4 Consignes de sécurité

L’ensemble de ces tâches doit être effectué par des personnes formées à cet effet.

Les réactifs utilisés dans la présente Norme internationale sont extrêmement corrosifs et potentiellement

très dangereux. Des précautions de sécurité sont absolument nécessaires en raison de la présence de

fumées toxiques, de réactifs très corrosifs, de températures élevées et de hautes pressions.

L’ensemble des modes opératoires doit être effectué sous une hotte ou un système hermétique à

ventilation forcée. L’utilisation de réactifs très oxydants peut entraîner la formation d’intermédiaires

2 © ISO 2012 – Tous droits réservés
---------------------- Page: 6 ----------------------
ISO 12914:2012(F)

organiques explosifs, notamment en cas de manipulation d’échantillons à forte teneur en matière

organique. Ne pas ouvrir les récipients pressurisés avant refroidissement. Éviter tout contact avec les

produits chimiques et les produits de réaction gazeux.
5 Principe

Il convient de traiter l’échantillon pour laboratoire conformément aux principes de l’ISO 11464 afin de produire

un échantillon pour essai homogène à partir duquel une prise d’essai peut être sous-échantillonnée et digérée

par de l’eau régale selon le mode opératoire de chauffage suivant.

Extraction par micro-ondes à 175 °C ± 5 °C pendant 10 min ± 1 min dans un récipient hermétique, suivie d’une

filtration et d’un ajustement du volume dans une fiole jaugée.
6 Interférences et sources d’erreurs

En raison de la volatilité de certains composés, il est important de veiller à ne pas chauffer l’échantillon

avant l’extraction et à empêcher la diffusion des produits de réaction volatils susceptibles de se former

pendant l’extraction. Le broyage des échantillons comporte un risque de contamination de l’échantillon par

l’environnement (par exemple air, poussière, usure de l’équipement de broyage). Une perte des composés

volatils est possible en raison de températures élevées (par exemple une température de séchage supérieure

à 40 °C peut entraîner une perte de mercure).

Pendant le dosage des éléments traces, toute contamination doit être évitée. Le récipient dans lequel

l’échantillon est livré et stocké peut être une source d’erreurs. Le matériau du récipient doit être choisi de façon

qu’il n’absorbe pas les éléments à doser (par exemple du Hg élémentaire peut s’infiltrer dans les parois en

polyéthylène très rapidement et dans les deux directions; le verre peut quant à lui contaminer les échantillons

avec ses éléments constitutifs tels que B, Na, K et Al).

Pour le dosage des éléments formant les composés volatils (par exemple Hg, As), une attention particulière

doit être prêtée au prétraitement des échantillons.

En utilisant les modes opératoires d’extraction décrits, il est possible que de grandes parties de l’échantillon

demeurent non dissoutes.

Un extrait ayant une matrice très acide et très riche en sel dissous peut provoquer des interférences lors des

opérations de mesurage.

Selon la concentration des éléments recherchés, une attention particulière doit être prêtée au nettoyage de

l’équipement de laboratoire. Il est recommandé de nettoyer soigneusement l’ensemble de l’équipement de

laboratoire et de laisser l’équipement tremper pendant au moins une nuit dans de l’acide nitrique à 1 % à 5 %.

Un soin particulier doit être apporté afin de s’assurer que la prise d’essai est en contact avec le mélange acide

dans le récipient de réaction. Il convient d’utiliser des régulateurs d’ébullition tels que des billes de verre, à

condition qu’ils ne contiennent aucun composant contaminant l’échantillon.
Certains éléments recherchés peuvent êt
...

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