SIST EN ISO 15192:2021

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
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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
below or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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 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.
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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
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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
2+
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].
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oSIST prEN ISO 15192:2020
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— 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].
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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oSIST prEN ISO 15192:2020
ISO/DIS 15192:2020(E)

7.1 Water
Water complying with the requirements for ISO 3696 grade 2 water (electrical conductivity less than
-1
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)
4
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.
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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).
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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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©  ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
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Published in Switzerland

ii © ISO 2010 – All rights reserved

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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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oSIST prEN ISO 15192:2019
ISO 15192:2010(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15192 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical
methods and soil characteristics.

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oSIST prEN ISO 15192:2019
ISO 15192:2010(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
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
2+
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)
3
(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
−1
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).
4
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
2
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
...