SIST ISO 14254:2006
Soil quality - Determination of exchangeable acidity in barium chloride extracts
Soil quality - Determination of exchangeable acidity in barium chloride extracts
The document describes a method for the determination of echangeable acidity in barium chloride extracts of soil samples obtained.
Qualité du sol - Détermination de l'acidité échangeable dans un extrait au chlorure de baryum
La présente Norme internationale spécifie une méthode de détermination de l'acidité échangeable dans des extraits par chlorure de baryum d'échantillons de sol prélevés conformément à l'ISO 11260. La procédure décrite dans la présente Norme internationale concerne principalement la détermination de l'acidité échangeable totale par titrage à une valeur limite de pH fixe (voir note). Deux autres procédures facultatives sont également décrites, portant respectivement sur le titrage de l'acidité par détermination de l'acidité H+ libre et de la concentration d'aluminium dans les extraits. La présente Norme internationale est applicable à tous les types d'échantillon séchés à l'air qui ont été prétraités conformément à l'ISO 11464. NOTE Le titrage de l'acidité échangeable au moyen d'une valeur limite de pH fixe peut ne pas être propre à un type d'acide donné. La valeur limite de pH retenue est 7,8, ce qui correspond à la précipitation complète des ions AI +3 dans des solutions synthétiques. Le titrage d'extraits de sol à ce pH peut également inclure certaines espèces plus faiblement ionisées ou des composés organiques faiblement acides.
Kakovost tal - Določanje izmenljive kislosti v ekstraktih barijevega klorida
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INTERNATIONAL ISO
STANDARD 14254
First edition
2001-08-15
Soil quality — Determination of
exchangeable acidity in barium chloride
extracts
Qualité du sol — Détermination de l'acidité échangeable dans un extrait au
chlorure de baryum
Reference number
ISO 14254:2001(E)
© ISO 2001
---------------------- Page: 1 ----------------------
ISO 14254:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be
edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file,
parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, elec-
tronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's mem-
ber 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.ch
Web www.iso.ch
Printed in Switzerland
©
ii ISO 2001 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14254:2001(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14254 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee
SC 3, Chemical methods and soil characteristics.
©
ISO 2001 – All rights reserved iii
---------------------- Page: 3 ----------------------
INTERNATIONAL STANDARD ISO 14254:2001(E)
Soil quality — Determination of exchangeable acidity in barium
chloride extracts
1 Scope
This International Standard specifies a method for the determination of exchangeable acidity in barium chloride
extracts of soil samples obtained according to ISO 11260.
The procedure described herein mainly concerns the determination of total exchangeable acidity by means of a
fixed-pH end-point titration (see note). Two optional procedures are also given, describing respectively,
+
determinations of free H acidity and of aluminium in the extracts.
This International Standard is applicable to all types of air-dry soil samples which have been pretreated in
accordance with ISO 11464.
NOTE Titration of exchangeable acidity by means of a fixed-pH end-point may not be specific to a given acid species. The end-
+3
point pH value retained is 7,8, corresponding to complete precipitation of Al ions in synthetic solutions. Titration of soil extracts
to this pH may also include some more weakly ionized species or weak acid organic compounds.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 11260, Soil quality — Determination of effective cation exchange capacity and base saturation level using
barium chloride solution
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
−1 −1
The soil sample is extracted in accordance with ISO 11260. The 0,1 mol� l extract is titrated with a 0,05 mol� l
NaOH solution up to pH = 7,8. The use of phenolphthalein as indicator is allowed, but shall be specified in the test
report.
+
An alternative method for determination of the free H acidity is proposed, in which sodium fluoride is added to the
soil extract before the titration (BaF precipitates but an excess of NaF is not necessary). Aluminium ions are
2
+
complexed and only the H acidity is detected during the titration process.
Two other optional methods for the determination of aluminium are proposed, using respectively flame atomic
absorption spectrometry and inductively coupled plasma emission spectrometry.
©
ISO 2001 – All rights reserved 1
---------------------- Page: 4 ----------------------
ISO 14254:2001(E)
4Reagents
Use only reagents of recognized analytical grade and distilled or deionized water for all solutions which shall be
stoved in suitable plastics bottles.
−1 �
4.1 Water having an electrical conductivity not higher than 0,2 mS� m at 25 C (grade 2 water in accordance
with ISO 3696).
4.2 Disodium tetraborate decahydrate (borax),Na B O ·10H O (molecular mass = 381,5) of a purity> 99,5 %,
2 4 7 2
which should be stored in a tightly closed bottle.
4.3 Buffer solutions for pH-meter calibration.
�
4.3.1 Buffer solution pH = 4,00 (20 C): Dissolve 10,21 g� 0,01 g of potassium hydrogen phthalate, C H KO ,
8 5 4
in water (4.1) and dilute to 1 000 ml.
�
4.3.2 Buffer solution pH = 7,00 (20 C): Dissolve 3,800 g� 0,005 g of potassium dihydrogen phosphate,
KH PO , and 3,415 g� 0,005 g of disodium hydrogen phosphate, Na HPO , in water (4.1) and dilute to 1 000 ml.
2 4 2 4
�
4.3.3 Buffer solution pH = 9,22 (20 C): Dissolve 3,800 g� 0,005 g of disodium tetraborate decahydrate,
Na B O ·10H O, in water (4.1) and dilute to 1 000 ml.
2 4 7 2
Commercial buffer solutions can be used in accordance with the manufacturer’s instructions.
4.4 Indicators (optional)
4.4.1 Methyl orange (colour change between pH = 3,0 and pH = 4,4): 0,100 g� 0,005 g in 100 ml of water.
pH = 4,2 pH = 6,2 0,200 g� 0,005 g 100 ml
4.4.2 Methyl red (colour change between and ): in of ethanol.
4.4.3 Phenolphthalein (colour change between pH = 8,2 and pH = 10,00): 1,00 g� 0,01 g in 100 ml of ethanol.
−1
4.5 Hydrochloric acid,c(HCl)= 1 mol� l
−1 −1
Dilute 83 ml of concentrated hydrochloric acid (d = 1,19 g� ml � 12 mol� l ) with water to 1 000 ml. This
solution shall be standardized by means of borax (4.2) following the reaction:
–2 +
5H O+B O +2H �4H BO
2 4 7 3 3
A mass of borax of about 1,928 g dissolved in about 100 ml of water (4.1) (heat slightly to accelerate dissolution) will
−1
need 10 ml of a solution of hydrochloric acid containing exactly 1 mol� l to be neutralized.
An end-point at pH = 5 shall be considered, or methyl red used as indicator. The concentration of this solution shall
be teste
...
SLOVENSKI STANDARD
SIST ISO 14254:2006
01-september-2006
.DNRYRVWWDO'RORþDQMHL]PHQOMLYHNLVORVWLYHNVWUDNWLKEDULMHYHJDNORULGD
Soil quality - Determination of exchangeable acidity in barium chloride extracts
Qualité du sol - Détermination de l'acidité échangeable dans un extrait au chlorure de
baryum
Ta slovenski standard je istoveten z: ISO 14254:2001
ICS:
13.080.10 .HPLMVNH]QDþLOQRVWLWDO Chemical characteristics of
soils
SIST ISO 14254:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 14254:2006
---------------------- Page: 2 ----------------------
SIST ISO 14254:2006
INTERNATIONAL ISO
STANDARD 14254
First edition
2001-08-15
Soil quality — Determination of
exchangeable acidity in barium chloride
extracts
Qualité du sol — Détermination de l'acidité échangeable dans un extrait au
chlorure de baryum
Reference number
ISO 14254:2001(E)
© ISO 2001
---------------------- Page: 3 ----------------------
SIST ISO 14254:2006
ISO 14254:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be
edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file,
parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, elec-
tronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's mem-
ber 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.ch
Web www.iso.ch
Printed in Switzerland
©
ii ISO 2001 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 14254:2006
ISO 14254:2001(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14254 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee
SC 3, Chemical methods and soil characteristics.
©
ISO 2001 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 14254:2006
---------------------- Page: 6 ----------------------
SIST ISO 14254:2006
INTERNATIONAL STANDARD ISO 14254:2001(E)
Soil quality — Determination of exchangeable acidity in barium
chloride extracts
1 Scope
This International Standard specifies a method for the determination of exchangeable acidity in barium chloride
extracts of soil samples obtained according to ISO 11260.
The procedure described herein mainly concerns the determination of total exchangeable acidity by means of a
fixed-pH end-point titration (see note). Two optional procedures are also given, describing respectively,
+
determinations of free H acidity and of aluminium in the extracts.
This International Standard is applicable to all types of air-dry soil samples which have been pretreated in
accordance with ISO 11464.
NOTE Titration of exchangeable acidity by means of a fixed-pH end-point may not be specific to a given acid species. The end-
+3
point pH value retained is 7,8, corresponding to complete precipitation of Al ions in synthetic solutions. Titration of soil extracts
to this pH may also include some more weakly ionized species or weak acid organic compounds.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 11260, Soil quality — Determination of effective cation exchange capacity and base saturation level using
barium chloride solution
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
−1 −1
The soil sample is extracted in accordance with ISO 11260. The 0,1 mol� l extract is titrated with a 0,05 mol� l
NaOH solution up to pH = 7,8. The use of phenolphthalein as indicator is allowed, but shall be specified in the test
report.
+
An alternative method for determination of the free H acidity is proposed, in which sodium fluoride is added to the
soil extract before the titration (BaF precipitates but an excess of NaF is not necessary). Aluminium ions are
2
+
complexed and only the H acidity is detected during the titration process.
Two other optional methods for the determination of aluminium are proposed, using respectively flame atomic
absorption spectrometry and inductively coupled plasma emission spectrometry.
©
ISO 2001 – All rights reserved 1
---------------------- Page: 7 ----------------------
SIST ISO 14254:2006
ISO 14254:2001(E)
4Reagents
Use only reagents of recognized analytical grade and distilled or deionized water for all solutions which shall be
stoved in suitable plastics bottles.
−1 �
4.1 Water having an electrical conductivity not higher than 0,2 mS� m at 25 C (grade 2 water in accordance
with ISO 3696).
4.2 Disodium tetraborate decahydrate (borax),Na B O ·10H O (molecular mass = 381,5) of a purity> 99,5 %,
2 4 7 2
which should be stored in a tightly closed bottle.
4.3 Buffer solutions for pH-meter calibration.
�
4.3.1 Buffer solution pH = 4,00 (20 C): Dissolve 10,21 g� 0,01 g of potassium hydrogen phthalate, C H KO ,
8 5 4
in water (4.1) and dilute to 1 000 ml.
�
4.3.2 Buffer solution pH = 7,00 (20 C): Dissolve 3,800 g� 0,005 g of potassium dihydrogen phosphate,
KH PO , and 3,415 g� 0,005 g of disodium hydrogen phosphate, Na HPO , in water (4.1) and dilute to 1 000 ml.
2 4 2 4
�
4.3.3 Buffer solution pH = 9,22 (20 C): Dissolve 3,800 g� 0,005 g of disodium tetraborate decahydrate,
Na B O ·10H O, in water (4.1) and dilute to 1 000 ml.
2 4 7 2
Commercial buffer solutions can be used in accordance with the manufacturer’s instructions.
4.4 Indicators (optional)
4.4.1 Methyl orange (colour change between pH = 3,0 and pH = 4,4): 0,100 g� 0,005 g in 100 ml of water.
pH = 4,2 pH = 6,2 0,200 g� 0,005 g 100 ml
4.4.2 Methyl red (colour change between and ): in of ethanol.
4.4.3 Phenolphthalein (colour change between pH = 8,2 and pH = 10,00): 1,00 g� 0,01 g in 100 ml of ethanol.
−1
4.5 Hydrochloric acid,c(HCl)= 1 mol� l
−1 −1
Dilute 83 ml of concentrated hydrochloric acid (d = 1,19 g� ml � 12 mol� l )
...
INTERNATIONAL ISO
STANDARD 14254
First edition
2001-08-15
Soil quality — Determination of
exchangeable acidity in barium chloride
extracts
Qualité du sol — Détermination de l'acidité échangeable dans un extrait au
chlorure de baryum
Reference number
ISO 14254:2001(E)
© ISO 2001
---------------------- Page: 1 ----------------------
ISO 14254:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be
edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file,
parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, elec-
tronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's mem-
ber 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.ch
Web www.iso.ch
Printed in Switzerland
©
ii ISO 2001 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14254:2001(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14254 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee
SC 3, Chemical methods and soil characteristics.
©
ISO 2001 – All rights reserved iii
---------------------- Page: 3 ----------------------
INTERNATIONAL STANDARD ISO 14254:2001(E)
Soil quality — Determination of exchangeable acidity in barium
chloride extracts
1 Scope
This International Standard specifies a method for the determination of exchangeable acidity in barium chloride
extracts of soil samples obtained according to ISO 11260.
The procedure described herein mainly concerns the determination of total exchangeable acidity by means of a
fixed-pH end-point titration (see note). Two optional procedures are also given, describing respectively,
+
determinations of free H acidity and of aluminium in the extracts.
This International Standard is applicable to all types of air-dry soil samples which have been pretreated in
accordance with ISO 11464.
NOTE Titration of exchangeable acidity by means of a fixed-pH end-point may not be specific to a given acid species. The end-
+3
point pH value retained is 7,8, corresponding to complete precipitation of Al ions in synthetic solutions. Titration of soil extracts
to this pH may also include some more weakly ionized species or weak acid organic compounds.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 11260, Soil quality — Determination of effective cation exchange capacity and base saturation level using
barium chloride solution
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
−1 −1
The soil sample is extracted in accordance with ISO 11260. The 0,1 mol l extract is titrated with a 0,05 mol l
NaOH solution up to pH = 7,8. The use of phenolphthalein as indicator is allowed, but shall be specified in the test
report.
+
An alternative method for determination of the free H acidity is proposed, in which sodium fluoride is added to the
soil extract before the titration (BaF precipitates but an excess of NaF is not necessary). Aluminium ions are
2
+
complexed and only the H acidity is detected during the titration process.
Two other optional methods for the determination of aluminium are proposed, using respectively flame atomic
absorption spectrometry and inductively coupled plasma emission spectrometry.
©
ISO 2001 – All rights reserved 1
---------------------- Page: 4 ----------------------
ISO 14254:2001(E)
4Reagents
Use only reagents of recognized analytical grade and distilled or deionized water for all solutions which shall be
stoved in suitable plastics bottles.
−1
4.1 Water having an electrical conductivity not higher than 0,2 mS m at 25 C (grade 2 water in accordance
with ISO 3696).
4.2 Disodium tetraborate decahydrate (borax),Na B O ·10H O (molecular mass = 381,5) of a purity> 99,5 %,
2 4 7 2
which should be stored in a tightly closed bottle.
4.3 Buffer solutions for pH-meter calibration.
4.3.1 Buffer solution pH = 4,00 (20 C): Dissolve 10,21 g 0,01 g of potassium hydrogen phthalate, C H KO ,
8 5 4
in water (4.1) and dilute to 1 000 ml.
4.3.2 Buffer solution pH = 7,00 (20 C): Dissolve 3,800 g 0,005 g of potassium dihydrogen phosphate,
KH PO , and 3,415 g 0,005 g of disodium hydrogen phosphate, Na HPO , in water (4.1) and dilute to 1 000 ml.
2 4 2 4
4.3.3 Buffer solution pH = 9,22 (20 C): Dissolve 3,800 g 0,005 g of disodium tetraborate decahydrate,
Na B O ·10H O, in water (4.1) and dilute to 1 000 ml.
2 4 7 2
Commercial buffer solutions can be used in accordance with the manufacturer’s instructions.
4.4 Indicators (optional)
4.4.1 Methyl orange (colour change between pH = 3,0 and pH = 4,4): 0,100 g 0,005 g in 100 ml of water.
pH = 4,2 pH = 6,2 0,200 g 0,005 g 100 ml
4.4.2 Methyl red (colour change between and ): in of ethanol.
4.4.3 Phenolphthalein (colour change between pH = 8,2 and pH = 10,00): 1,00 g 0,01 g in 100 ml of ethanol.
−1
4.5 Hydrochloric acid,c(HCl)= 1 mol l
−1 −1
Dilute 83 ml of concentrated hydrochloric acid (d = 1,19 g ml 12 mol l ) with water to 1 000 ml. This
solution shall be standardized by means of borax (4.2) following the reaction:
–2 +
5H O+B O +2H 4H BO
2 4 7 3 3
A mass of borax of about 1,928 g dissolved in about 100 ml of water (4.1) (heat slightly to accelerate dissolution) will
−1
need 10 ml of a solution of hydrochloric acid containing exactly 1 mol l to be neutralized.
An end-point at pH = 5 shall be considered, or meth
...
NORME ISO
INTERNATIONALE 14254
Première édition
2001-08-15
Qualité du sol — Détermination de l'acidité
échangeable dans un extrait au chlorure de
baryum
Soil quality — Determination of exchangeable acidity in barium chloride
extracts
Numéro de référence
ISO 14254:2001(F)
© ISO 2001
---------------------- Page: 1 ----------------------
ISO 14254:2001(F)
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riat central à l'adresse donnée ci-dessous.
© ISO 2001
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous quel-
que 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 au 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.ch
Web www.iso.ch
ImpriméenSuisse
©
ii ISO 2001 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 14254:2001(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 3.
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 de la présente Norme internationale 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.
La Norme internationale ISO 14254 a été élaborée par le comité technique ISO/TC 190, Qualité du sol,sous-comité
SC 3, Méthodes chimiques et caractéristiques du sol.
©
ISO 2001 – Tous droits réservés iii
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NORME INTERNATIONALE ISO 14254:2001(F)
Qualité du sol — Détermination de l'acidité échangeable dans un
extrait au chlorure de baryum
1 Domaine d'application
La présente Norme internationale spécifie une méthode de détermination de l'acidité échangeable dans des extraits
par chlorure de baryum d'échantillons de sol prélevés conformément à l’ISO 11260.
La procédure décrite dans la présente Norme internationale concerne principalement la détermination de l'acidité
échangeable totale par titrage à une valeur limite de pH fixe (voir note). Deux autres procédures facultatives sont
+
également décrites, portant respectivement sur le titrage de l'acidité par détermination de l'acidité H libreetdela
concentration d'aluminium dans les extraits.
La présente Norme internationale est applicable à tous les types d'échantillon séchés à l'air qui ont été prétraités
conformément à l’ISO 11464.
NOTE Le titrage de l'acidité échangeable au moyen d'une valeur limite de pH fixe peut ne pas être propre à un type d'acide
+3
donné. La valeur limite de pH retenue est 7,8, ce qui correspond à la précipitation complète des ions Al dans des solutions
synthétiques. Le titrage d'extraits de sol à ce pH peut également inclure certaines espèces plus faiblement ionisées ou des
composés organiques faiblement acides.
2 Références normatives
Les documents normatifs suivants contiennent des dispositions qui, par suite de la référence qui y est faite, consti-
tuent des dispositions valables pour la présente Norme internationale. Pour les références datées, les amendements
ultérieurs ou les révisions de ces publications ne s'appliquent pas. Toutefois, les parties prenantes aux accords fon-
dés sur la présente Norme internationale sont invitées à rechercher la possibilité d'appliquer les éditions les plus ré-
centes des documents normatifs indiqués ci-après. Pour les références non datées, la dernière édition du document
normatif en référence s'applique. Les membres de l'ISO et de la CEI possèdent le registre des Normes internationa-
les en vigueur.
ISO 3696, Eau pour laboratoire à usage analytique — Spécification et méthodes d'essai
ISO 11260, Qualité du sol — Détermination de la capacité d'échange cationique effective et du taux de saturation en
bases échangeables à l'aide d'une solution de chlorure de baryum
ISO 11464, Qualité du sol — Prétraitement des échantillons pour analyses physico-chimiques
ISO 11465, Qualité du sol — Détermination de la teneur pondérale en matière sèche et en eau — Méthode gravimé-
trique
3Principe
−1
L'échantillon de sol est extrait conformément à l’ISO 11260. L'extrait à 0,1 mol� l est titré avec une solution de
−1
NaOH à 0,05 mol� l jusqu'à la valeur pH = 7,8. L'emploi de phénolphtaléine comme indicateur est autorisé mais
doit être spécifié dans le rapport d'essai.
+
Une autre méthode de détermination de l'acidité H libre est proposée, dans laquelle on ajoute du fluorure de sodium
à l'extrait de sol avant de procéder au titrage (le BaF se précipite, mais un excédent de NaF n'est pas nécessaire).
2
+
Les ions d'aluminium sont complexés et seule l'acidité H est détectée au cours de la procédure de titrage.
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ISO 2001 – Tous droits réservés 1
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ISO 14254:2001(F)
Deux autres méthodes facultatives pour la détermination de l'aluminium sont proposées, qui utilisent respectivement
la spectrométrie d'absorption atomique de flamme et la spectrométrie par émission de plasma à couplage inductif.
4 Réactifs
Utiliser uniquement des réactifs analytiquement purs et de l'eau distillée ou déminéralisée pour toutes les solutions,
lesquelles doivent être stockées dans des flacons en plastique appropriés.
−1 �
4.1 Eau, ayant une conductibilité électrique d'au plus 0,2 mS� m à 25 C (eau de qualité 2 conformément à
l’ISO 3696).
4.2 Décahydrate de tétraborate disodique (borax),Na B O �10H O (masse moléculaire = 381,5) d'une pureté
2 4 7 2
> 99,5 %, qu'il convient de stocker dans un flacon fermé adapté.
4.3 Solutions tampons, pour l'étalonnage du pH-mètre.
�
pH = 4,00 20 C 10,21 g� 0,01 g
4.3.1 Solution tampon ( ): dissoudre d'hydrogènophtalate de potassium,
C H KO , dans de l'eau (4.1) et diluer à 1 000 ml.
8 5 4
�
4.3.2 Solution tampon pH = 7,00 (20 C): dissoudre 3,800 g� 0,005 g de dihydrogènophosphate de potassium,
KH PO , et 3,415 g� 0,005 g d'hydrogénophosphate de disodium, Na HPO , dans de l'eau (4.1) et diluer à
2 4 2 4
1 000 ml.
�
4.3.3 Solution tampon pH = 9,22 (20 C): dissoudre 3,800 g� 0,005 g de décahydrate de tétraborate disodique,
Na B O ,10H O, dans de l'eau (4.1) et diluer à 1 000 ml.
2 4 7 2
On peut aussi utiliser des solutions tampons du commerce en se conformant aux instructions du fabricant.
4.4 Indicateurs (facultatifs)
4.4.1 Méthylorange (changement de couleur entre pH = 3,0 et pH = 4,4): 0,100 g� 0,005 g dans 100 ml d'eau.
4.4.2 Rouge de méthyle (changement de couleur entre pH = 4,2 et pH = 6,2): 0,200 g� 0,005 g dans 100 ml
d'éthanol.
4.4.3 Phénolphtaléine (changement de couleur entre pH = 8,2 et pH = 10,0): 1,00 g� 0,01 g dans 100 ml
d'éthanol.
−1
4.5 Acide chlorhydrique,c(HCl)= 1 mol� l
−1 −1
Diluer 83 ml d'acide chlorhydrique concentré (d = 1,19 g� ml � 12 mol� l ) avec de l'eau à 1 000 ml. Cette
solution est ensuite normalisée en utilisant du borax (4.2) après la réaction:
–2 +
5H O+B O +2H ����H BO
2 4 7 3 3
Une masse de borax de 1,928 g dissoute dans environ 100 ml d'eau (4.1) (chauffer légèrement pour accélérer la
−1
dissolution) nécessitera une solution de 10 ml d'acide chlorhydrique contenant exactement 1 mol� l pour être
neutralisée.
On envisagera l'utilisation d'une valeur limite de pH = 5 ou de rouge de méthyle comme indicateur. On doit contrôler
la concentration de cette solution au moins une fois par mois.
On peut aussi utilis
...
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