Soil quality - Determination of effective cation exchange capacity (CEC) and exchangeable cations using a hexamminecobalt trichloride solution (ISO 23470:2018)

This document specifies a method for the determination of cation exchange capacity (CEC) and the
content of exchangeable cations (Al, Ca, Fe, K, Mg Mn, Na) in soils using a hexamminecobalt(III)chloride
solution as extractant. For soils containing calcium carbonate a calcite saturated hexamminecobalt(III)
chloride solution is specified particularly for determination of exchangeable Ca. This document is
applicable to all types of air-dry soil samples which have been prepared according to ISO 11464.

Bodenbeschaffenheit - Bestimmung der effektiven Kationenaustauschkapazität (KAK) und der austauschbaren Kationen mit Hexammincobalt(III)chlorid-Lösung (ISO 23470:2018)

Dieses Dokument legt ein Verfahren zur Bestimmung der Kationenaustauschkapazität (KAK) und des Gehaltes an austauschbaren Kationen (Al, Ca, Fe, K, Mg, Mn, Na) in Böden unter Verwendung einer Hexammincobalt(III)chlorid-Lösung als Extraktionsmittel fest. Bei Böden, die Calciumcarbonat enthalten, ist eine calcitgesättigte Hexammincobalt(III)chlorid-Lösung besonders für die Bestimmung des austauschbaren Ca angegeben. Dieses Dokument gilt für alle Arten von lufttrockenen Bodenproben, die nach ISO 11464 vorbereitet wurden.

Qualité du sol - Détermination de la capacité d'échange cationique (CEC) effective et des cations échangeables à l'aide d'une solution de trichlorure de cobaltihexammine (ISO 23470:2018)

Le présent document spécifie une méthode de détermination de la capacité d'échange cationique (CEC) et de la teneur en cations échangeables (Al, Ca, Fe, K, Mg, Mn, Na) dans le sol à l'aide d'une solution de trichlorure de cobaltihexammine utilisée comme réactif d'extraction. Pour les sols contenant du carbonate de calcium, une solution de trichlorure de cobaltihexammine saturée en calcite est spécifiée, en particulier pour la détermination du Ca échangeable. Le présent document est applicable à tous les types d'échantillons de sol séchés à l'air qui ont été préparés conformément à l'ISO 11464.

Kakovost tal - Določevanje efektivne kationske izmenjalne kapacitete in izmenljivih kationov z uporabo raztopine heksaminokobaltovega triklorida (ISO 23470:2018)

Ta dokument določa metodo za določevanje kationske izmenjalne kapacitete (CEC) in vsebnost izmenljivih kationov (Al, Ca, Fe, K, Mg Mn, Na) v tleh z uporabo raztopine heksaminokobaltovega (III) klorida kot ekstraktanta. Za tla, ki vsebujejo kalcijev karbonat, je kalcitna nasičena raztopina heksaminokobaltovega (III) klorida določena posebej za določevanje izmenljivega kalcija. Ta dokument se uporablja za vse vrste vzorcev tal, posušene na zraku, ki so bili pripravljeni v skladu s standardom ISO 11464.

General Information

Status
Published
Public Enquiry End Date
02-Jan-2018
Publication Date
12-Nov-2018
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
06-Nov-2018
Due Date
11-Jan-2019
Completion Date
13-Nov-2018

RELATIONS

Buy Standard

Standard
SIST EN ISO 23470:2018
English language
30 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN ISO 23470:2018
01-december-2018
1DGRPHãþD
SIST EN ISO 23470:2011

.DNRYRVWWDO'RORþHYDQMHHIHNWLYQHNDWLRQVNHL]PHQMDOQHNDSDFLWHWHLQL]PHQOMLYLK

NDWLRQRY]XSRUDERUD]WRSLQHKHNVDPLQRNREDOWRYHJDWULNORULGD ,62
Soil quality - Determination of effective cation exchange capacity (CEC) and

exchangeable cations using a hexamminecobalt trichloride solution (ISO 23470:2018)

Bodenbeschaffenheit - Bestimmung der effektiven Kationenaustauschkapazität (KAK)
und der austauschbaren Kationen mit Hexammincobalt(III)chlorid-Lösung (ISO
23470:2018)

Qualité du sol - Détermination de la capacité d'échange cationique (CEC) effective et

des cations échangeables à l'aide d'une solution de trichlorure de cobaltihexammine

(ISO 23470:2018)
Ta slovenski standard je istoveten z: EN ISO 23470:2018
ICS:
13.080.10 .HPLMVNH]QDþLOQRVWLWDO Chemical characteristics of
soils
SIST EN ISO 23470:2018 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST EN ISO 23470:2018
---------------------- Page: 2 ----------------------
SIST EN ISO 23470:2018
EN ISO 23470
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2018
EUROPÄISCHE NORM
ICS 13.080.20 Supersedes EN ISO 23470:2011
English Version
Soil quality - Determination of effective cation exchange
capacity (CEC) and exchangeable cations using a
hexamminecobalt trichloride solution (ISO 23470:2018)

Qualité du sol - Détermination de la capacité d'échange Bodenbeschaffenheit - Bestimmung der effektiven

cationique (CEC) effective et des cations échangeables Kationenaustauschkapazität (KAK) und der

à l'aide d'une solution de trichlorure de austauschbaren Kationen mit Hexammincobalt-

cobaltihexammine (ISO 23470:2018) trichlorid-Lösung (ISO 23470:2018)
This European Standard was approved by CEN on 10 September 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 23470:2018 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 23470:2018
EN ISO 23470:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 23470:2018
EN ISO 23470:2018 (E)
European foreword

This document (EN ISO 23470:2018) has been prepared by Technical Committee ISO/TC 190 "Soil

quality" in collaboration with Technical Committee CEN/TC 444 “Test methods for environmental

characterization of solid matrices” the secretariat of which is held by NEN.

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 April 2019, and conflicting national standards shall be

withdrawn at the latest by April 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 23470:2011.

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,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 23470:2018 has been approved by CEN as EN ISO 23470:2018 without any modification.

---------------------- Page: 5 ----------------------
SIST EN ISO 23470:2018
---------------------- Page: 6 ----------------------
SIST EN ISO 23470:2018
INTERNATIONAL ISO
STANDARD 23470
Second edition
2018-09
Soil quality — Determination of
effective cation exchange capacity
(CEC) and exchangeable cations using
a hexamminecobalt(III)chloride
solution
Qualité du sol — Détermination de la capacité d'échange cationique
(CEC) effective et des cations échangeables à l'aide d'une solution de
trichlorure de cobaltihexammine
Reference number
ISO 23470:2018(E)
ISO 2018
---------------------- Page: 7 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................ 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus ..................................................................................................................................................................................................................... 3

7 Procedure..................................................................................................................................................................................................................... 4

7.1 Test portion ................................................................................................................................................................................................ 4

7.2 Exchange reaction ................................................................................................................................................................................ 4

7.3 Determination of CEC ........................................................................................................................................................................ 4

7.3.1 General...................................................................................................................................................................................... 4

7.3.2 Determination of ammonia nitrogen by distillation ......................................................................... 4

7.3.3 Spectrophotometric determination ................................................................................................................ 5

7.3.4 Spectrometric determination of cobalt ........................................................................................................ 7

7.4 Determination of cobalt and exchangeable cations ................................................................................................ 7

7.4.1 General...................................................................................................................................................................................... 7

7.4.2 Standard solutions for exchangeable cations .......................................................................................... 8

7.4.3 Standard solutions for cobalt ................................................................................................................................ 8

7.4.4 Spectrometric determination of exchangeable cations .................................................................. 9

7.4.5 Spectrometric determination of cobalt ........................................................................................................ 9

7.4.6 Calculation of exchangeable cations ............................................................................................................... 9

8 Test report ................................................................................................................................................................................................................10

9 Validation ..................................................................................................................................................................................................................10

Annex A (informative) Comparison of different methods for the determination of effective CEC ....11

Annex B (informative) Results of the interlaboratory comparison for extraction with

hexamminecobalt(III)chloride ...........................................................................................................................................................15

Annex C (informative) Results of the interlaboratory comparison for extraction with calcite

saturated hexamminecobalt(III)chloride solution ........................................................................................................17

Annex D (informative) Carbonate and sulfate field model .........................................................................................................18

Annex E (informative) Effect of minimization of Ca errors by calcite saturation of

hexamminecobalt .............................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................22

© ISO 2018 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3,

Chemical and physical characterization.

This second edition cancels and replaces the first edition (ISO 23470:2007), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— the scope has been broadened for soils with a pH > 6,5;
— a new Annex C has been added;
— a new Annex D has been added;
— a new Annex E has been added;
— the document has been editorially revised.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(E)
Introduction

The cation exchange capacity (CEC) of soils and clays as well as the exchangeable cation population are

essential features of soil fertility. Various attempts have been made in the literature to measure these

parameters accurately and efficiently. The completeness of cation exchange on the other hand is not

absolute but should be comparable between different methods. Traditional methods used ammonium

or barium as exchangeable cations which require repeated treatments to ensure complete cation

exchange. The oldest one-step CEC method is based on hexamminecobalt(III)chloride solution which

has a much stronger affinity to soil clay minerals than the typical cations of the soil solution (usually Ca,

[11]

Mg, Na and K). The principle of this method was published by Morel (1958) and has been modified

[7]

by Ciesielski and Sterckeman (1997) . This method, as described in this document, is very efficient

and comparable to the established CEC methods. It determines the effective CEC when used for soils

with pH value of <6,5.

All CEC methods including hexamminecobalt(III)chloride have typical limitations such as inflation of

exchangeable cations caused by dissolution of carbonates, sulfates or other soluble minerals (compare

also ISO 13536). Carbonate dissolution is one of the most frequently occurring source of error (e.g. in the

procedure described in ISO 13536), hence, many studies focused on minimization of their dissolution or

correction of the dissolved fraction. Reference [13] summarized the discussion and presented solutions

for this analytical problem. For calcareous soils or clays, the authors used exchange solutions that were

previously equilibrated with calcite. In the course of the extraction, dissolution of carbonates present

in the samples was minimized largely and resulting exchangeable Ca values were nearly free of errors.

It was a great success compared to methods used in the past (Annex E). This method using calcite-

[6]

saturated hexamminecobalt(III)chloride exchange solutions was published as VDLUFA-method .

The resulting exchangeable cation values agreed well with the total CEC when tested in a round robin

(Annex C) which is a good measure for the plausibility of the results. Using different solution/solid

ratios, identical exchangeable cation values were measured indicating absence of systematic errors

caused by mineral dissolution (compare the model described in Reference [12], for detection of inflated

exchangeable Ca values as described in Annex D). This calcite-saturated hexamminecobalt(III)chloride

exchange solution should be used for calcareous soils and clays only, practically for soils with pH

values of ≥6,5 in which only Ca, Mg, Na and K are present as “exchangeable bases”. Thus, the results are

comparable to the determination of potential CEC (for example according to ISO 13563). This method

was introduced to avoid erroneous (inflated) Ca values.

Hexamminecobalt(III)chloride is recommended as extractant for non-calcareous soils with a pH value

of ≤6,5. As the pH value of a soil suspension in the hexamminecobalt(III)chloride solution is close to the

pH value of the suspension in water, this method is considered to give the effective CEC, i.e. the CEC at

the soil pH value (e.g. according to ISO 11260).
© ISO 2018 – All rights reserved v
---------------------- Page: 11 ----------------------
SIST EN ISO 23470:2018
---------------------- Page: 12 ----------------------
SIST EN ISO 23470:2018
INTERNATIONAL STANDARD ISO 23470:2018(E)
Soil quality — Determination of effective cation exchange
capacity (CEC) and exchangeable cations using a
hexamminecobalt(III)chloride solution

WARNING — Persons using this document should be familiar with usual laboratory practice.

This document does not purport to address all of the safety problems, if any, associated with its

use. It is the responsibility of the user to establish appropriate safety and health practices.

IMPORTANT — It is absolutely essential that tests, conducted in accordance with this document,

be carried out by suitably qualified staff.
1 Scope

This document specifies a method for the determination of cation exchange capacity (CEC) and the

content of exchangeable cations (Al, Ca, Fe, K, Mg Mn, Na) in soils using a hexamminecobalt(III)chloride

solution as extractant. For soils containing calcium carbonate a calcite saturated hexamminecobalt(III)

chloride solution is specified particularly for determination of exchangeable Ca. This document is

applicable to all types of air-dry soil samples which have been prepared according to ISO 11464.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

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

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

Gravimetric method
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Principle

Cations adsorbed to a soil sample are exchanged with the hexamminecobalt ions of an aqueous

solution, with a (60 ± 5) min shaking at a temperature of (20 ± 2) °C. The CEC is obtained by difference

between the initial quantity of hexamminecobalt in solution and the quantity remaining in the extract

after the exchange reaction. The measurement of hexamminecobalt concentration in the extract can

be performed by determination of total ammonium nitrogen (see 7.3.2), direct spectrophotometric

measurement (see 7.3.3) or total cobalt concentrations (see 7.3.4).

The quantities of exchanged cations are determined on the same extract using spectrometric methods

such as inductively coupled plasma atomic emission spectrometry (ICP-AES). In case the calcite

saturated hexamminecobalt(III)chloride solution is used, the initial Ca concentration of the pure

© ISO 2018 – All rights reserved 1
---------------------- Page: 13 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(E)

exchange solution shall be determined and subtracted from each exchange solution that has been in

contact with soil or clay.
NOTE 1 Exchangeable acidity can also be measured in the hexamminecobalt extract.

NOTE 2 When exchangeable cations are held in micropores into which ammonium ions can enter but

hexamminecobalt ions cannot, the CEC and exchangeable cations values determined with this method can be

smaller than those determined by ammonium acetate method. This has been observed in some soils containing

allophane and imogolite, for example soils developed on volcanic rocks.

NOTE 3 When gypsiferous soils or clays are examined, gypsum is dissolved even in calcite saturated

hexamminecobalt(III)chloride solution throughout the exchange experiment, which in turn increases

measureable Ca concentrations. Dolomite dissolution on the other hand is lowered very much in calcite saturated

hexamminecobalt(III)chloride solution and resulting Ca and Mg concentrations are nearly error-free.

NOTE 4 Variation of extraction intensity, particularly time, was proven to be insignificant for bentonites

tested in an interlaboratory CEC and exchangeable cation study when varied between 15 min and 120 min

using different dispersion techniques such as hand-shaking, vibrating table, rocking platform, sonication, and

end-over-end shaking. This was verified for Cu-triethylenetetramine which is similar to cobalthexammine(III)

[13]
chloride .
5 Reagents
Only reagents of recognized analytical quality shall be used.

5.1 Distilled or demineralized water, exempt from the elements under analysis and having a

conductivity under 0,5 μS/cm.
5.2 Hexamminecobalt(III)chloride solution, β[Co(NH ) ]Cl = 0,016 6 mol/l.
3 6 3

Take care that hexamminecobalt(III)chloride is free of adsorbed water before use. Dissolve, to within

a milligram, 4,458 g of hexamminecobalt(III)chloride in a volumetric flask containing 700 ml of water

(5.1). Make up to the volume and mix.

Supplier: e.g. STREM , 93-2708. CAS Number: 10534-89-1. 50 g are needed for about 10 l of exchange

solution.
5.3 Anti-bumping granules (e.g. pumice stone in grain form, glass beads).
5.4 Boric acid, β(H BO ) = 40 g/l.
3 3
5.5 Tashiro indicator.

Dissolve 2,0 g of methyl red and 1,0 g of methylene blue in 1 000 ml of 95 % ethanol.

5.6 Phenolphthalein.
Dissolve 1 g of phenolphthalein in 1 000 ml of 95 % ethanol.
5.7 Sodium hydroxide solution, with a density of 33 %.
5.8 Sulfuric acid, c(H SO ) = 0,025 mol/l.
2 4
5.9 Ammonium sulfate, for analysis.

1) STREM (strem.com) is an example of a product available commercially. This information is given for the

convenience of users of this document and does not constitute an endorsement by ISO of the product named.

Equivalent products may be used if they can be shown to lead to the same results.

2 © ISO 2018 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(E)
5.10 Stock solutions of Al, Ca, Fe, K, Mg, Mn, Na, β(Me) = 1,000 g/l.

These solutions are supplied with a certified composition from a reputable source and are checked on a

regular basis.
5.11 Calcite saturated hexamminecobalt (III)chloride solution.

Fill up a 2 l beaker with hexamminecobalt(III)chloride solution (5.2). Add 2 g of fine-ground calcite. This

mixture is placed in an ultrasonic bath for 30 min. To minimize temperature effects on the solubility

of calcite, the solution is stirred for a further 30 min using a magnetic stirrer. After switching off the

stirrer, undissolved calcite is allowed to settle overnight. The 2 l beaker is protected by a plastic foil on

top during calcite saturation. The solution may be decanted or filtered, however, addition of un-reacted

(settled) calcite to the soil sample should be avoided. Two litres (2 l) of exchange solution can be used

for approximately 34 samples (34 × 50 ml) plus 2 blanks (2 × 50 ml).

NOTE Reagents 5.3 to 5.9 are prepared only in the case when determination of CEC is carried out by

determination of ammonia nitrogen using distillation. They are not needed when spectrophotometric

determination is used.
6 Apparatus

6.1 Analytical balance, the weighing uncertainty range of which will not exceed ±0,1 % of the test

portion mass.

6.2 Containers for shaking, tightly stoppered, rigid or non-rigid wall, having a volume between 75 ml

and 100 ml.
6.3 50 ml dispenser, set at ±0,25 ml of the delivered volume.

6.4 End-over-end shaker, allowing the permanent suspension of the soil/extraction solution mixture,

placed in ambient air at (20 ± 2) °C.
6.5 Centrifuge and relevant centrifuge vials.

Centrifugation time and speed depend on the type of centrifuge and are selected with a view of securing

a clear supernatant. 4 000 r/min for 20 min are generally sufficient but special care shall be taken due

to the high content of fixed hexamminecobalt ions on colloidal particles.

6.6 Distillation apparatus, the different parts of the apparatus shall be assembled ensuring tightness

in order to prevent any loss of ammonia or entrainment of sodium hydroxide.
6.7 Microburette.

6.8 Spectrophotometer, allowing measurements to be performed at wavelengths 380 nm and

475 nm, equipped with a 10 mm path length measuring cell.
6.9 Inductively coupled plasma atomic emission spectrometer.
6.10 Ultrasonic bath.
6.11 Magnetic stirrer and magnetic stir bar.
© ISO 2018 – All rights reserved 3
---------------------- Page: 15 ----------------------
SIST EN ISO 23470:2018
ISO 23470:2018(E)
7 Procedure
7.1 Test portion
Pretreat soil in accordance with ISO 11464.

If Q is the number of centimoles of positive charges provided by a given volume of hexamminecobalt

(III)chloride solution, the centimoles of positive charges carried by the test portion shall lie between

Q/10 and Q/3 inclusive.

Table 1 gives examples of suitable test portions for a range of expected CEC values.

Table 1 — Test portions (in 50 ml of solution 5.2)
Measured CEC, in cmol /kg <2,5 2,5 to 5 5 to 10 10 to 32 32 to 64
Test portion, g 10 10 5 2,5 1,25

Weigh to within 0,1 % the selected mass of the test portion (see ISO 11464) and transfer to a container

for shaking (6.2). Evaluation of plausible CEC and exchangeable cation values may be performed using

the diagram type called Carbonate and Sulphate Field Model (CSF model); see Reference [12]. Two

different sample masses are used and plausibility is given when both resulting values (any exchangeable

cation pair or the CECs) lie on the y = x line as shown in Annex D.
7.2 Exchange reaction

Add 50 ml of the hexamminecobalt(III)chloride solution (5.2) or calcite saturated hexamminecobalt(III)

chloride solution (5.11) and shake for (60 ± 5) min by means of the shaker (6.4). Centrifuge by means

of 6.5. Collect the clear filtrate or supernatant. Carry out the determinations no later than 24 h after

extraction at the latest, otherwise, ascertain that the storage conditions do not influence the test result.

Such storage may be done after diluting the samples in acidified solutions.

Produce an extraction “blank” under the same conditions, but without the test portion.

7.3 Determination of CEC
7.3.1 General

The measurement of hexamminecobalt concentration in the extract can be performed by determination

of total ammonium nitrogen (according to 7.3.2), direct spectrophotometric measurement (according

to 7.3.3) or total cobalt concentrations (according to 7.3.4).
7.3.2 Determination of ammonia nitrogen by distillation
7.3.2.1 Procedure

Pipette 10 ml of the extract (see 7.2) into the distilling apparatus flask. Make up to the volume, to

around 200 ml, with water (5.1). Add the anti-bumping granules (5.3).
Add to the distillate recovery c
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.