prEN ISO 15192

Characterization of soil and waste - Determination of Chromium(VI) in solid material by alkaline digestion and ion chromatography with spectrophotometric detection (ISO/DIS 15192:2020)

2019-10-24: WI created erroneously as adoption of ISO 15192:2010 then corrected to be under VA ISO lead based on ISO ed.2

Charakterisierung von Abfällen und Boden - Bestimmung von sechswertigem Chrom in Feststoffen durch alkalischen Aufschluss und Ionenchromatographie mit photometrischer Detektion (ISO/DIS 15192:2020)

Qualité du sol - Dosage du chrome(VI) dans les matériaux solides par digestion alcaline et chromatographie ionique avec détection spectrophotométrique (ISO/DIS 15192:2020)

L'ISO 15192:2010 spécifie une méthode de dosage du Cr(VI) dans les déchets solides et les sols par digestion alcaline et chromatographie ionique avec détection spectrophotométrique. Cette méthode peut être utilisée pour déterminer les fractions massiques de Cr(VI) dans les solides supérieures à 0,1 mg/kg.

Karakterizacija tal in odpadkov - Določevanje kroma Cr (VI) v trdnem mediju z alkalnim razklopom in ionsko kromatografijo s spektrofotometrično detekcijo (ISO/DIS 15192:2020)

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 15192:2020
01-junij-2020
Karakterizacija tal in odpadkov - Določevanje kroma Cr (VI) v trdnem mediju z
alkalnim razklopom in ionsko kromatografijo s spektrofotometrično detekcijo
(ISO/DIS 15192:2020)

Characterization of soil and waste - Determination of Chromium(VI) in solid material by

alkaline digestion and ion chromatography with spectrophotometric detection (ISO/DIS

15192:2020)
Charakterisierung von Abfällen und Boden - Bestimmung von sechswertigem Chrom in

Feststoffen durch alkalischen Aufschluss und Ionenchromatographie mit photometrischer

Detektion (ISO/DIS 15192:2020)

Qualité du sol - Dosage du chrome(VI) dans les matériaux solides par digestion alcaline

et chromatographie ionique avec détection spectrophotométrique (ISO/DIS 15192:2020)

Ta slovenski standard je istoveten z: prEN ISO 15192
ICS:
13.080.10 Kemijske značilnosti tal Chemical characteristics of
soils
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
oSIST prEN ISO 15192:2020 en,fr,de

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

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oSIST prEN ISO 15192:2020
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oSIST prEN ISO 15192:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 15192
ISO/TC 190/SC 3 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-04-17 2020-07-10
Characterization of soil and waste — Determination of
Chromium(VI) in solid material by alkaline digestion and
ion chromatography with spectrophotometric detection
ICS: 13.080.10
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 15192:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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

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ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)
Contents Page

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

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

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

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

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

4 Safety remarks ........................................................................................................................................................................................................ 2

5 Principle ........................................................................................................................................................................................................................ 2

5.1 Digestion....................................................................................................................................................................................................... 2

5.2 Determination ......................................................................................................................................................................................... 2

5.3 Interferences and sources of error ........................................................................................................................................ 2

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

6.1 Digestion equipment .......................................................................................................................................................................... 3

6.2 Filtration equipment .......................................................................................................................................................................... 3

6.3 Membrane filters ................................................................................................................................................................................... 3

6.4 Ion chromatographic system ...................................................................................................................................................... 3

6.5 Ion chromatographic column ..................................................................................................................................................... 3

6.6 Detection system ................................................................................................................................................................................... 3

7 Reagents ........................................................................................................................................................................................................................ 3

8 Sample pretreatment ....................................................................................................................................................................................... 5

9 Alkaline digestion procedure .................................................................................................................................................................. 6

10 Analytical procedure ........................................................................................................................................................................................ 6

10.1 General information ........................................................................................................................................................................... 6

10.2 Instrumental set-up ............................................................................................................................................................................ 7

10.3 Calibration .................................................................................................................................................................................................. 7

10.4 Test solution measurement .......................................................................................................................................................... 7

10.5 Quality Control ........................................................................................................................................................................................ 7

10.5.1 General...................................................................................................................................................................................... 7

10.5.2 Blank test solution .......................................................................................................................................................... 8

10.5.3 Verification of method ........................................................................................................................................... ...... 8

10.5.4 Duplicate samples ........................................................................................................................................................... 8

10.5.5 Cr(VI) spiked samples ................................................................................................................................................. 8

10.5.6 Cr(III) spiked samples ................................................................................................................................................. 8

10.5.7 Interpretation of quality control data............................................................................................................ 9

11 Calculation .................................................................................................................................................................................................................. 9

12 Expression of results ........................................................................................................................................................................................ 9

13 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Alternative methods for direct determination of Cr(VI) in the

alkaline digestion solution .....................................................................................................................................................................11

Annex B (informative) Ion chromatographic system........................................................................................................................12

Annex C (informative) Requirements for test portion preparation ..................................................................................13

Annex D (informative) Validation .........................................................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................18

© ISO 2020 – All rights reserved iii
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(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).

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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 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 15192:2010), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— The text has been editorially revised, including updating of references;
— Annex D has been deleted.

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 2020 – All rights reserved
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)
Introduction

Under environmental conditions chromium in compounds exists in the trivalent, Cr(III), or the

hexavalent, Cr(VI) state. Cr(III) is an essential trace element for mammals, including man, whereas it is

presumed that Cr(VI) compounds are genotoxic and potentially carcinogenic in humans. Interconversion

of trivalent and hexavalent chromium species can occur during sample preparation and analysis, but

these processes are minimised, to the extent possible, by the sample preparation methods prescribed

by this standard.
© ISO 2020 – All rights reserved v
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oSIST prEN ISO 15192:2020
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oSIST prEN ISO 15192:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 15192:2020(E)
Characterization of soil and waste — Determination of
Chromium(VI) in solid material by alkaline digestion and
ion chromatography with spectrophotometric detection
1 Scope

This document describes the determination of Cr(VI) in solid waste material and soil by alkaline

digestion and ion chromatography with spectrophotometric detection. This method can be used to

determine Cr(VI)-mass fractions in solids higher than 0,1 mg/kg.

NOTE In case of reducing or oxidising waste matrix no valid Cr(VI) content can be reported.

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 3696, Water for analytical laboratory use — Specification and test methods
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

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

EN 15002, Characterization of waste — Preparation of test portions from the laboratory sample

EN 15934, Sludge, treated biowaste, soil and waste — Calculation of dry matter fraction after determination

of dry residue or water content
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

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

— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
alkaline digestion

process of obtaining a solution containing the analyte of interest from a sample under alkaline

conditions. Alkaline digestion may or may not involve complete dissolution of the sample

3.2
speciation analysis

activities of measuring the quantity of one or more individual chemical species in a sample, e. g. Cr(VI)

in a particular sample or matrix
© ISO 2020 – All rights reserved 1
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)
4 Safety remarks

Anyone dealing with waste and soil analysis has to be aware of the typical risks of the material

irrespective of the parameters determined. Waste and soil samples may contain hazardous (e. g. toxic,

reactive, flammable, infectious) substances, which can be liable to biological and/or chemical reaction.

Consequently, it is recommended that these samples should be handled with special care. The gases

which may be produced by microbiological or chemical activity are potentially flammable and can

pressurise sealed bottles. Bursting bottles are likely to result in hazardous shrapnel, dust and/or aerosol.

National regulations should be followed with respect to all hazards associated with this method.

Avoid any contact with the skin, ingestion or inhalation of Cr(VI) compounds. Cr(VI) compounds are

genotoxic and potentially carcinogenic to humans.
5 Principle
5.1 Digestion

This document describes an alkaline digestion procedure for extracting Cr(VI) from soluble, adsorbed

and precipitated forms of chromium compounds in solid waste materials and soil. To quantify the

content of Cr(VI) in a solid matrix, three criteria shall be satisfied:
1) digestion solution shall solubilize all species of Cr(VI);

2) conditions of the digestion shall not induce reduction of native Cr(VI) to Cr(III);

3) method shall not cause oxidation of native Cr(III) contained in the sample to Cr(VI).

The alkaline digestion described in this document meets these criteria for a wide spectrum of solid

matrices. Under the alkaline conditions of the digestion, neglectable reduction of Cr(VI) or oxidation of

native Cr(III) is expected. The additon of Mg in a phosphate buffer to the alkaline solution prevents

air oxidation of trivalent chromium [1], [5], [8].

NOTE Background on methods for the determination of Cr(VI) in solid samples is given in [3], [4], [5].

5.2 Determination

Quantification of Cr(VI) in the alkaline digestion solution should be performed using a suitable

technique with appropriate accuracy. For this purpose ion chromatography is used to separate

Cr(VI) from interferences. Following this ion chromatographic separation, Cr(VI) is measured

spectrophotometrically either at 365 nm (direct UV detection) or after post-column derivatisation

with 1,5-diphenylcarbazide in acid solution at 540 nm. Post-column derivatisation involves reaction

of 1,5-diphenylcarbazide with Cr(VI) to produce trivalent chromium and diphenylcarbazone. These

then combine to form a trivalent chromium-diphenylcarbazone complex containing the characteristic

magenta chromagen (λ = 540 nm).
max

NOTE The choice of detection method is based upon the required sensitivity. Direct UV detection is less

sensitive than detection after post-column derivatisation with 1,5-diphenylcarbazide.

Hyphenated methods with ion chromatographic separation and detection techniques, such as

inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma atomic

emission spectroscopy (ICP-AES), may be used once validation of the chosen analytical method has

been performed.
5.3 Interferences and sources of error

— Use of ion chromatography is necessary for the separation of Cr(VI) from possible interferences in

the alkaline digestion solution from solid material [6].
2 © ISO 2020 – All rights reserved
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)

— For waste materials or soils, where the Cr(III)/Cr(VI) ratio is expected to be high, Cr(VI) results

may be biased due to method induced oxidation. This can be particularly expected in soils high in

Mn content and amended with soluble Cr(III) salts or freshly precipitated Cr(OH) [3].

— Cr(VI) can be reduced to Cr(III) during digestion from the sample due to reaction with reducing

agents such as e.g. divalent iron. This problem is minimised in the described procedure using

alkaline digestion solution [5].

— Cr(III) can be oxidised to Cr(VI) in hot alkaline solutions. This problem is minimised in the described

procedure by adding magnesium to the alkaline digestion solution [2], [3], [5], [8].

— Overloading the analytical column capacity with high concentrations of anionic species (e. g.

chloride) may cause underestimation of Cr(VI) [9].
6 Apparatus
6.1 Digestion equipment

— hotplate with a magnetic stirrer, thermostatically controlled with a digestion vessel of 250 ml

covered with a watch glass; or

— heating block with a magnetic stirrer, thermostatically controlled with a digestion vessel of 250 ml

covered with a watch glass

NOTE Other thermostatically controlled digestion equipment with a magnetic stirrer can be used once

validation has been performed.
6.2 Filtration equipment
suitable for using 0,45-µm membrane filters.
6.3 Membrane filters
0,45-µm pore size, chemically inert.
6.4 Ion chromatographic system

All components which come into contact with the sample or eluent stream shall be comprised of inert

materials, e. g. polyetherether ketone (PEEK), as shall all connecting tubing (see Annex B).

6.5 Ion chromatographic column
suitable for chromate separation with a sufficient ion exchange capacity.
6.6 Detection system
— UV-VIS spectrophotometer at 365 nm; or
— VIS spectrophotometer at 540 nm after post column derivatisation.
7 Reagents

During the analysis, only use reagents of recognised analytical grade, and water as specified in 7.1.

© ISO 2020 – All rights reserved 3
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ISO/DIS 15192:2020(E)
7.1 Water

Water complying with the requirements for ISO 3696 grade 2 water (electrical conductivity less than

0,1 mS m equivalent to resistivity greater than 0,01 MΩ m at 25 °C). It is recommended that the water

used is obtained from a purification system that delivers ultrapure water having a resistivity greater

than 0,18 MΩ m (usually expressed by manufacturers of water purification systems as 18 MΩ cm).

7.2 Sulphuric acid (H SO ),
2 4
concentrated, ρ(H SO ) ~ 1,84 g/ml, w(H SO ) ~ 98 %
2 4 2 4
7.3 Sodium carbonate (Na CO ),
2 3
anhydrous, w(Na CO ) > 99,9 %
2 3
7.4 1,5-Diphenylcarbazide ((C H .NH.NH) CO),
6 5 2
w((C H .NH.NH) CO) > 98 %
6 5 2
7.5 Propanone (acetone) (C H O)
3 6
7.6 Methanol (CH O)
7.7 Potassium dichromate (K Cr O ), w(K Cr O ) > 99,9 %
2 2 7 2 2 7
Dry to constant weight at 110 °C, cool and store in a dessiccator.
7.8 Sodium hydroxide (NaOH), w(NaOH) > 99 %
7.9 Magnesium chloride hexahydrate (MgCl .6H O), w(MgCl .6H O) > 99 %
2 2 2 2
7.10 Dipotassium hydrogenphosphate (K HPO ), w(K HPO ) > 99 %
2 4 2 4
7.11 Potassium dihydrogenphosphate (KH PO ), w(KH PO ) > 99 %
2 4 2 4
7.12 Lead chromate (PbCrO ), w(PbCrO ) > 99 %
4 4
7.13 Diphenylcarbazide reagent solution

Dissolve 0,125 g of 1,5-diphenylcarbazide (7.4) in 25 ml of propanone (7.5) or methanol (7.6) in a

250 ml volumetric flask. Fill 125 ml of water into a separate container, slowly add 7 ml of concentrated

sulphuric acid (7.2), swirl to mix and allow to cool. Degass with e. g. helium or argon for 5 min to 10 min

prior to adding to the 1,5-diphenylcarbazide solution. After combining the solutions, fill up to the mark

with water and degass additionally for 5 min to 10 min. The reagent solution is stable for 5 days.

7.14 Eluent solution

Use an eluent solution appropriate to separate chromate over the ion chromatographic column (6.5).

7.15 Alkaline digestion solution, 0,5 mol/l sodium hydroxide (NaOH) / 0,28 mol/l sodium carbonate

(Na CO )
2 3

Dissolve 20,0 g of sodium hydroxide (7.8) in approximately 500 ml of water (7.1). Add 30,0 g of sodium

carbonate (7.3) and swirl to mix. Quantitatively transfer the solution into a 1 l volumetric flask. Dilute

to the mark with water. The pH of the digestion solution must be checked before use. The pH shall be

11,5 or higher. Store in a polyethylene bottle at room temperature and prepare fresh monthly.

4 © ISO 2020 – All rights reserved
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ISO/DIS 15192:2020(E)
7.16 Calibration solutions of Cr(VI)
7.16.1 Cr(VI) standard stock solution, 1 000 mg/l Cr(VI)

Dissolve 0,282 9 g of potassium dichromate (7.7) in 75 ml of water (7.1) in a 100 ml volumetric flask.

Dilute to the mark with water (7.1), close and mix thoroughly. Store the solution in a polypropylene

bottle for a maximum period of 1 year.

Alternatively a commercial standard solution with a certified Cr(VI) concentration traceable to national

standards can be used. Observe the manufacturer's expiration date or recommended shelf life.

7.16.2 Cr(VI) working standard solution, 10 mg/l Cr(VI)

Accurately pipette 10,0 ml of the Cr(VI) standard stock solution (7.16.1) into a 1 l volumetric flask,

dilute to the mark with water (7.1), close and mix thoroughly. Prepare this solution fresh monthly.

7.16.3 Cr(VI) calibration solutions

Prepare a set of at least 5 calibration solutions by diluting the Cr(VI) working standard solution with a

1 + 1 diluted alkaline digestion solution (7.15). Add 25 ml of the alkaline digestion solution (7.15) into a

50 ml volumetric flask, pipette accurately the appropriate volume of Cr(VI) working standard solution

(7.16.2) into the volumetric flask and dilute to the mark with water (7.1), close and mix thoroughly.

Prepare these calibration solutions fresh daily.
7.16.4 Cr(VI) spiking solutions
The Cr(VI) working standard solution (7.16.2) can be used to spike samples.
7.17 Phosphate buffer solution,

0,5 mol/l dipotassiumhydrogenphosphate (K HPO )/0,5 mol/l potassiumdihydrogenphosphate

2 4
(KH PO ), pH 7.
2 4

Dissolve 87,09 g K HPO (7.10) and 68,04 g of KH PO (7.11) in approximately 700 ml of water and swirl

2 4 2 4

to mix. Transfer the solution into a 1 l volumetric flask. Dilute to the mark with water.

7.18 Magnesium chloride solution

Dissolve 85,4 g MgCl .6H O (7.9) in a 100 ml volumetric flask, dilute to the mark with water (7.1), close

2 2
and mix thoroughly.
7.19 Chromium chloride hexahydrate (CrCl .6H O), w(CrCl .6H O) > 96 %
3 2 3 2
7.20 Cr(III) spiking solution

Use a commercial standard solution with a certified Cr(III) concentration, e. g 1 000 mg/l Cr(III)

traceable to national standards. Observe the manufacturer's expiration date or recommended shelf life.

Alternatively dissolve an appropriate known amount of chromium chloride hexahydrate (7.19) in water

(7.1) in a 100 ml volumetric flask, dilute to the mark with water (7.1), close and mix thoroughly. Store

the solution in a polypropylene bottle for a maximum period of 1 year. Before using, determine the Cr

concentration of the spiking solution.
8 Sample pretreatment

Samples shall be collected using appropriate devices and placed in containers that do not contain

stainless steel (e. g. plastic, glass).
© ISO 2020 – All rights reserved 5
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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)

Samples shall be stored field moist at (4 ± 2) °C until analysis. Waste samples shall be homogenised

according to EN 15002, soil samples according to ISO 11464. Soil samples shall preferably be air-dried

before digestion.

Particle size reduction below 250 µm is necessary for solid waste and soil especially when Cr(VI) is

suspected to be included in the matrix, whereby heating and contact with stainless steel have to be

avoided.
After digestion the sample shall be analysed as soon as possible.

NOTE Cr(VI) has been shown to be quantitatively stable in field moist soil samples for 30 d from the time

of sample collection. In addition, Cr(VI) has also been shown to be stable in the alkaline digest for up to 7 d after

digestion from soil [2].
9 Alkaline digestion procedure
9.1 General

Use either the hotplate or heating block method prescribed in 9.2 to prepare test solutions for

determination of Cr(VI) in solid waste materials and soil.
9.2 Preparation of test solutions using a hotplate or heating block

9.2.1 Adjust the temperature setting by preparing and monitoring a temperature blank (a 250 ml

vessel filled with 50 ml digestion solution). Maintain a digestion solution temperature of (92,5 ± 2,5) °C.

Do not allow the solution to boil or evaporate to dryness.
9.2.2 Transfer (2,5 ± 0,1) g of the test portion weighed to the nearest
...

SLOVENSKI STANDARD
oSIST prEN ISO 15192:2019
01-november-2019
Kakovost tal - Določevanje šestvalentnega kroma Cr (VI) v trdnem mediju z
alkalnim razklopom in ionsko kromatografijo s spektrofotometrično detekcijo (ISO
15192:2010)

Soil quality - Determination of chromium(VI) in solid material by alkaline digestion and

ion chromatography with spectrophotometric detection (ISO 15192:2010)
Charakterisierung von Abfällen und Boden - Bestimmung von sechswertigem Chrom in

Feststoffen durch alkalischen Aufschluss und Ionenchromatographie mit photometrischer

Detektion (ISO 15192:2010)

Qualité du sol - Dosage du chrome(VI) dans les matériaux solides par digestion alcaline

et chromatographie ionique avec détection spectrophotométrique (ISO 15192:2010)
Ta slovenski standard je istoveten z: prEN ISO 15192
ICS:
13.080.10 Kemijske značilnosti tal Chemical characteristics of
soils
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
oSIST prEN ISO 15192:2019 en,fr,de

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

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oSIST prEN ISO 15192:2019
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oSIST prEN ISO 15192:2019
INTERNATIONAL ISO
STANDARD 15192
First edition
2010-11-15
Soil quality — Determination of
chromium(VI) in solid material by alkaline
digestion and ion chromatography with
spectrophotometric detection
Qualité du sol — Dosage du chrome(VI) dans les matériaux solides par
digestion alcaline et chromatographie ionique avec détection
spectrophotométrique
Reference number
ISO 15192:2010(E)
ISO 2010
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oSIST prEN ISO 15192:2019
ISO 15192:2010(E)
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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
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 15192:2019
ISO 15192:2010(E)
Contents Page

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

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

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

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

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

4 Safety......................................................................................................................................................2

5 Principle .................................................................................................................................................2

5.1 Digestion ................................................................................................................................................2

5.2 Determination ........................................................................................................................................2

5.3 Interferences and sources of error......................................................................................................3

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

7 Reagents ................................................................................................................................................3

8 Sample pretreatment.............................................................................................................................5

9 Alkaline digestion procedure ...............................................................................................................6

9.1 General ...................................................................................................................................................6

9.2 Preparation of test solutions using a hotplate or heating block......................................................6

10 Analytical procedure.............................................................................................................................6

10.1 General information ..............................................................................................................................6

10.2 Instrumental set-up ...............................................................................................................................6

10.3 Calibration..............................................................................................................................................7

10.4 Test solution measurement..................................................................................................................7

10.5 Quality control .......................................................................................................................................7

10.5.1 General ...................................................................................................................................................7

10.5.2 Blank test solution ................................................................................................................................7

10.5.3 Verification of method...........................................................................................................................7

10.5.4 Duplicate samples.................................................................................................................................8

10.5.5 Cr(VI) spiked samples...........................................................................................................................8

10.5.6 Cr(III) spiked samples ...........................................................................................................................8

10.5.7 Interpretation of quality control data...................................................................................................8

11 Calculation .............................................................................................................................................9

12 Expression of results............................................................................................................................9

13 Test report..............................................................................................................................................9

Annex A (informative) Alternative methods for direct determination of Cr(VI) in the alkaline

digestion solution................................................................................................................................11

Annex B (informative) Ion chromatographic system ....................................................................................12

Annex C (informative) Requirements for test portion preparation ..............................................................13

Annex D (informative) Background on methods for the determination of Cr(VI) in solid samples..........14

Annex E (informative) Validation interlaboratory comparison.....................................................................17

Bibliography......................................................................................................................................................21

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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 15192 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical

methods and soil characteristics.
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Introduction

Under environmental conditions, chromium in compounds exists in the trivalent, Cr(III), or the hexavalent,

Cr(VI), state. Cr(III) is an essential trace element for mammals, including man, whereas it is presumed that

Cr(VI) compounds are genotoxic and potentially carcinogenic in humans. Interconversion of trivalent and

hexavalent chromium species can occur during sample preparation and analysis, but these processes are

minimized, to the extent possible, by the sample preparation methods specified in this International Standard.

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INTERNATIONAL STANDARD ISO 15192:2010(E)
Soil quality — Determination of chromium(VI) in solid material
by alkaline digestion and ion chromatography with
spectrophotometric detection
1 Scope

This International Standard specifies a method for the determination of Cr(VI) in solid waste material and soil

by alkaline digestion and ion chromatography with spectrophotometric detection. This method can be used to

determine Cr(VI) mass fractions in solids greater than 0,1 mg/kg.

NOTE In the case of reducing or oxidizing waste matrix, no valid Cr(VI) mass fraction can be reported.

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 9174:1998, Water quality — Determination of chromium — Atomic absorption spectrometric methods

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

ISO 11885:2007, Water quality — Determination of selected elements by inductively coupled plasma optical

emission spectrometry (ICP-OES)

ISO 15586:2003, Water quality — Determination of trace elements using atomic absorption spectrometry with

graphite furnace

ISO 17294-2:2003, Water quality — Application of inductively coupled plasma mass spectrometry

(ICP-MS) — Part 2: Determination of 62 elements

EN 15002, Characterization of waste — Preparation of test portions from the laboratory sample

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

process for obtaining a solution containing the analyte of interest from a sample under alkaline conditions

NOTE Alkaline digestion may or may not involve complete dissolution of the sample.

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3.2
speciation analysis

activities for measuring the quantity of one or more individual chemical species in a sample

EXAMPLE Cr(VI) in a particular sample or matrix.
4 Safety

SAFETY PRECAUTIONS — Anyone dealing with waste and soil analysis has to be aware of the typical

risks of the material, irrespective of the parameters determined. Waste and soil samples may contain

hazardous (e.g. toxic, reactive, flammable, infectious) substances, which can be liable to biological

and/or chemical reaction. Consequently, it is recommended that these samples be handled with

special care. The gases which may be produced by microbiological or chemical activity are potentially

flammable and can pressurize sealed bottles. Bursting bottles are likely to result in hazardous

shrapnel, dust and/or aerosol. National regulations should be followed with respect to all hazards

associated with this method.

Avoid any contact with the skin, ingestion or inhalation of Cr(VI) compounds. Cr(VI) compounds are

genotoxic and potentially carcinogenic to humans.
5 Principle
5.1 Digestion

This International Standard describes an alkaline digestion procedure for extracting Cr(VI) from soluble,

adsorbed and precipitated forms of chromium compounds in solid waste materials and soil. To quantify the

mass fraction of Cr(VI) in a solid matrix, three criteria shall be satisfied:
a) the digestion solution shall solubilize all species of Cr(VI);

b) the conditions of the digestion shall not induce reduction of native Cr(VI) to Cr(III);

c) the method shall not cause oxidation of native Cr(III) contained in the sample to Cr(VI).

The alkaline digestion described in this International Standard meets these criteria for a wide spectrum of solid

matrices. Under the alkaline conditions of the digestion, neglectable reduction of Cr(VI) or oxidation of

native Cr(III) is expected. The additon of Mg in a phosphate buffer to the alkaline solution prevents air

oxidation of trivalent chromium (References [7], [12] and [38] in the Bibliography).

NOTE Background information on methods for the determination of Cr(VI) in solid samples is given in Annex D and

References [10], [11] and [12] in the Bibliography.
5.2 Determination

Quantification of Cr(VI) in the alkaline digestion solution should be performed using a suitable technique with

appropriate accuracy. For this purpose, ion chromatography is used to separate Cr(VI) from interferences.

Following this ion chromatographic separation, Cr(VI) is measured spectrophotometrically, either at 365 nm

[direct ultraviolet (UV) detection] or after post-column derivatization with 1,5-diphenylcarbazide in acid solution

at 540 nm. Post-column derivatization involves reaction of 1,5-diphenylcarbazide with Cr(VI) to produce

trivalent chromium and diphenylcarbazone. These then combine to form a trivalent chromium-

diphenylcarbazone complex containing the characteristic magenta chromagen (λ = 540 nm).

max

NOTE 1 The choice of the detection method is based upon the required sensitivity. Direct UV detection is less sensitive

than detection after post-column derivatization with 1,5-diphenylcarbazide.
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NOTE 2 Hyphenated methods with ion chromatographic separation and detection techniques, such as inductively

coupled plasma/mass spectrometry (ICP/MS) or inductively coupled plasma (atomic emission spectroscopy (ICP/AES),

can be used once validation of the chosen analytical method has been performed.
5.3 Interferences and sources of error

Use of ion chromatography is necessary for the separation of Cr(VI) from possible interferences in the alkaline

digestion solution from solid material (Reference [13] in the Bibliography) (see also D.3).

For waste materials or soils, where the Cr(III)/Cr(VI) ratio is expected to be high, Cr(VI) results may be biased

due to method-induced oxidation. This can be particularly expected in soils high in manganese (Mn) content

and amended with soluble Cr(III) salts or freshly precipitated Cr(OH) (Reference [10] in the Bibliography)

(see also D.2).

Cr(VI) can be reduced to Cr(III) during digestion of the sample, due to reaction with reducing agents such as,

for example, divalent iron. This problem is minimized in the described procedure using alkaline digestion

solution (Reference [12] in the Bibliography) (see also D.2).

Cr(III) can be oxidized to Cr(VI) in hot alkaline solutions. This problem is minimized in the described procedure

by adding magnesium to the alkaline digestion solution (References [9], [10], [12] and [38] in the Bibliography)

(see also D.2).

Overloading the analytical column capacity with high concentrations of anionic species (e.g. chloride) may

cause underestimation of Cr(VI) (Reference [49] in the Bibliography).
6 Apparatus
Use ordinary laboratory apparatus and the following.

6.1 Digestion equipment, hotplate with a magnetic stirrer, thermostatically controlled, with a digestion

vessel of 250 ml covered with a watch-glass; or a heating block with a magnetic stirrer, thermostatically

controlled with a digestion vessel of 250 ml covered with a watch-glass.

NOTE Other thermostatically controlled digestion equipment with a magnetic stirrer can be used once validation has

been performed.
6.2 Filtration equipment, suitable for using 0,45 µm membrane filters.
6.3 Membrane filters, of pore size 0,45 µm, chemically inert.

6.4 Ion chromatographic system, all components which come into contact with the sample or eluent

stream shall be comprised of inert materials, e.g. polyetherether ketone (PEEK), as shall all connecting tubing

(see Annex B).

6.5 Ion chromatographic column, suitable for chromate separation with a sufficient ion-exchange capacity.

6.6 Detection system, ultraviolet/visible light (UV/VIS) spectrophotometer at 365 nm; or VIS

spectrophotometer at 540 nm after post-column derivatization.
7 Reagents

During the analysis, only use reagents of recognized analytical grade, and water as specified in 7.1.

7.1 Water.

Water complying with the requirements of ISO 3696 for grade 2 water (electrical conductivity less than

0,1 mS⋅m equivalent to a resistivity greater than 0,01 MΩ⋅m at 25 °C). It is recommended that the water

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used be obtained from a purification system that delivers ultrapure water having a resistivity greater than

0,18 MΩ⋅m (usually expressed by manufacturers of water-purification systems as 18 MΩ⋅cm).

7.2 Sulfuric acid (H SO ), concentrated, ρ(H SO ) ∼ 1,84 g/ml, w(H SO ) ∼ 98 %.
2 4 2 4 2 4
7.3 Sodium carbonate (Na CO ), anhydrous, w(Na CO ) > 99,9 %.
2 3 2 3
7.4 1,5-Diphenylcarbazide [(C H NHNH) CO], w[(C H NHNH) CO] > 98 %.
6 5 2 6 5 2
7.5 Acetone (C H O).
3 6
7.6 Methanol (CH O).
7.7 Potassium dichromate (K Cr O ), w(K Cr O ) > 99,9 %.
2 2 7 2 2 7
Dry to constant mass at 110 °C, cool and store in a dessiccator.
7.8 Sodium hydroxide (NaOH), w(NaOH) > 99 %.
7.9 Magnesium chloride hexahydrate (MgCl⋅6H O), w(MgCl⋅6H O) > 99 %.
2 2 2 2
7.10 Dipotassium hydrogenphosphate (K HPO ), w(K HPO ) > 99 %.
2 4 2 4
7.11 Potassium dihydrogenphosphate (KH PO ), w(KH PO ) > 99 %.
2 4 2 4
7.12 Lead chromate (PbCrO ), w(PbCrO ) > 99 %.
4 4
7.13 Diphenylcarbazide reagent solution.

Dissolve 0,125 g of 1,5-diphenylcarbazide (7.4) in 25 ml of acetone (7.5) or methanol (7.6) in a 250 ml

volumetric flask. Pour 125 ml of water (7.1) into a separate container, then slowly add 7 ml of concentrated

sulfuric acid (7.2), swirl to mix and allow to cool. Degas with, for example, helium or argon for 5 min to 10 min

prior to adding to the 1,5-diphenylcarbazide solution. After combining the solutions, fill up to the mark with

water and degas again for 5 min to 10 min. The reagent solution is stable for 5 days when stored at 2 °C to

8 °C in the dark.
7.14 Eluent solution.

Use an eluent solution that is appropriate to separate chromate over the ion chromatographic column (6.5).

7.15 Alkaline digestion solution, 0,5 mol/l sodium hydroxide (NaOH) and 0,28 mol/l sodium carbonate

(Na CO ).
2 3

Dissolve 20,0 g of sodium hydroxide (7.8) in approximately 500 ml of water (7.1). Add 30,0 g of sodium

carbonate (7.3) and swirl to mix. Quantitatively transfer the solution into a 1 l volumetric flask. Dilute to the

mark with water. The pH of the digestion solution shall be checked before use. The pH shall be 11,5 or higher.

Store in a polyethylene bottle at room temperature and prepare fresh monthly.
7.16 Calibration solutions of Cr(VI).
7.16.1 Cr(VI) standard stock solution, 1 000 mg/l Cr(VI).

Dissolve 0,282 9 g of potassium dichromate (7.7) in 75 ml of water (7.1) in a 100 ml volumetric flask. Dilute to

the mark with water (7.1), close and mix thoroughly. Store the solution in a polypropylene bottle for a

maximum period of 1 year.

Alternatively, a commercial standard solution with a certified Cr(VI) concentration traceable to national

standards can be used. Observe the manufacturer's expiration date or recommended shelf life.

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7.16.2 Cr(VI) working standard solution, 10 mg/l Cr(VI).

Accurately pipette 10,0 ml of the Cr(VI) standard stock solution (7.16.1) into a 1 l volumetric flask, dilute to the

mark with water (7.1), close and mix thoroughly. Prepare this solution fresh monthly.

7.16.3 Cr(VI) calibration solutions.

Prepare a set of at least five calibration solutions by diluting the Cr(VI) working standard solution with a 1 + 1

diluted alkaline digestion solution (7.15). Add 25 ml of the alkaline digestion solution to a 50 ml volumetric

flask, accurately pipette the appropriate volume of Cr(VI) working standard solution (7.16.2) into the volumetric

flask and dilute to the mark with water (7.1), close and mix thoroughly. Prepare these calibration solutions

fresh daily.
7.16.4 Cr(VI) spiking solutions.
The Cr(VI) working standard solution (7.16.2) can be used to spike samples.

7.17 Phosphate buffer solution, 0,5 mol/l dipotassiumhydrogenphosphate (K HPO ) and 0,5 mol/l

2 4
potassiumdihydrogenphosphate (KH PO ), pH 7.
2 4

Dissolve 87,09 g of K HPO (7.10) and 68,04 g of KH PO (7.11) in approximately 700 ml of water (7.1) and

2 4 2 4

swirl to mix. Transfer the solution into a 1 l volumetric flask. Dilute to the mark with water.

7.18 Magnesium chloride solution.

Dissolve 85,4 g of MgCl⋅6H O (7.9) in a 100 ml volumetric flask, dilute to the mark with water (7.1), close and

2 2
mix thoroughly.
7.19 Chromium chloride hexahydrate (CrCl⋅6H O), w(CrCl⋅6H O) > 96 %.
3 2 3 2
7.20 Cr(III) spiking solution.

Use a commercial standard solution with a certified Cr(III) concentration, e.g 1 000 mg/l Cr(III) traceable to

national standards. Observe the manufacturer's expiration date or recommended shelf life.

Alternatively, dissolve an appropriate known amount of chromium chloride hexahydrate (7.19) in water (7.1) in

a 100 ml volumetric flask, dilute to the mark with water, close and mix thoroughly. Store the solution in a

polypropylene bottle for a maximum period of 1 year. Before using, determine the Cr concentration of the

spiking solution.
8 Sample pretreatment

Soil samples shall be collected using appropriate devices and placed in containers that do not contain

stainless steel (e.g. plastics, glass).

Samples shall be stored in a field-moist state at (4 ± 2) °C until analysis. Waste samples shall be

homogenized in accordance with EN 15002; soil samples shall be homogenized in accordance with

ISO 11464. Soil samples shall preferably be air-dried before digestion.

Particle-size reduction below 250 µm is necessary for solid waste and soil, especially when Cr(VI) is

suspected to be included in the matrix, whereby heating and contact with stainless steel have to be avoided.

After digestion, the sample shall be analysed as soon as possible.

NOTE Cr(VI) has been shown to be quantitatively stable in field-moist soil samples for 30 days from the time of

sample collection. In addition, Cr(VI) has also been shown to be stable in the alkaline digest for up to 7 days after

digestion from soil (Reference [8] in the Bibliography).
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9 Alkaline digestion procedure
9.1 General

Use either the hotplate or heating-block method specified in 9.2 to prepare test solutions for the determination

of Cr(VI) in solid waste materials and soil.
9.2 Preparation of test solutions using a hotplate or heating block

9.2.1 Adjust the temperature setting by preparing and monitoring a temperature blank (a 250 ml vessel filled

with 50 ml of digestion solution). Maintain a digestion solution temperature of (92,5 ± 2,5) °C. Do not allow the

solution to boil or evaporate to dryness.

9.2.2 Transfer (2,5 ± 0,1) g of the test portion, weighed to the nearest 0,1 mg, into a clean 250 ml digestion

vessel.

NOTE For very high expected concentrations of Cr(VI), a smaller representative test portion can be used.

9.2.3 Add (50 ± 1) ml of the alkaline digestion solution (7.15) to each sample using a graduated cylinder,

and also add 1 ml of magnesium chloride solution (7.18) containing approximately 400 mg of MgCl and

0,5 ml of phosphate buffer solution (7.17). Cover all digestion vessels. If using a heating block, reflux

condensers can be used.

9.2.4 Heat the samples to (92,5 ± 2,5) °C while stirring continuously, then maintain the samples at

(92,5 ± 2,5) °C for at least 60 min while stirring continuously.

9.2.5 Cool each solution to room temperature. Transfer the contents quantitatively to the filtration

equipment (6.2), rinsing the digestion vessel three times with small portions of water (7.1). Filter through a

0,45 µm membrane filter (6.3). Rinse the filtration equipment (6.2) with water (7.1) and transfer the filtrate to a

100 ml volumetric flask and fill up to the mark with water (7.1).
NOTE Alternatively, the sample can be centrifuged or allowed to settle.
10 Analytical procedure
10.1 General information

The standard method for the determination of Cr(VI) in the alkaline digestion solution is the ion

chromatographic method with spectrophotometric detection as described in this clause.

NOTE In certain cases, direct determination of Cr(VI) in the alkaline digestion solution might be possible (see

Annex A).
10.2 Instrumental set-up

10.2.1 Set up the ion chromatograph in accordance with the manufacturer's instructions.

10.2.2 Adjust the flow rate of the eluent solution (7.14) to a value that is compatible with the columns used

(typically 0,3 ml/min to 1 ml/min).

10.2.3 If post-column derivatization occurs, optimize the ratio of eluent solution and reagent flow rates or

adjust the sulfuric acid concentration of the diphenylcarbazide reagent solution (7.13) to obtain the best signal-

to-background ratio. It is important that the ratio between the eluent solution and reagent flow rates be kept

constant, that the total flow rate does not exceed the maximum flow rate for the detector and that the

diphenylcarbazide reagent be present in excess. A typical value for the ratio between the eluent solution and

reagent flow rates is 3:1. After the flow rates are adjusted, allow the system to equilibrate for 15 min.

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10.2.4 In the case of direct detection, adjust the UV/VIS detector to measure within a range of 355 nm to

375 nm, preferably at 365 nm.

In the case of measuring after post-column derivatization with 1,5-diphenylcarbazide, adjust the VIS detector

to measure within a range of 530 nm to 550 nm, preferably at 540 nm.
10.3 Calibration
10.3.1 Inject a suitable volume (20 µl t
...