SIST EN ISO 15192:2021

SLOVENSKI STANDARD
01-november-2021
Nadomešča:
SIST EN 15192:2007
Tla in odpadki - Določevanje kroma Cr (VI) v trdnem mediju z alkalnim razklopom
in ionsko kromatografijo s spektrofotometrično detekcijo (ISO 15192:2021)
Soil and waste - Determination of Chromium(VI) in solid material by alkaline digestion
and ion chromatography with spectrophotometric detection (ISO 15192:2021)
Boden und Abfall - Bestimmung von sechswertigem Chrom in Feststoffen durch
alkalischen Aufschluss und Ionenchromatographie mit photometrischer Detektion (ISO
15192:2021
Déchets et sols - Dosage du chrome(VI) dans les matériaux solides par digestion
alcaline et chromatographie ionique avec détection spectrophotométrique (ISO
15192:2021)
Ta slovenski standard je istoveten z: EN ISO 15192:2021
ICS:
13.080.10 Kemijske značilnosti tal Chemical characteristics of
soils
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 15192
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2021
EUROPÄISCHE NORM
ICS 13.080.10 Supersedes EN 15192:2006
English Version
Soil and waste - Determination of Chromium(VI) in solid
material by alkaline digestion and ion chromatography
with spectrophotometric detection (ISO 15192:2021)
Déchets et sols - Dosage du chrome(VI) dans les Charakterisierung von Abfällen und Boden -
matériaux solides par digestion alcaline et Bestimmung von sechswertigem Chrom in Feststoffen
chromatographie ionique avec détection durch alkalischen Aufschluss und
spectrophotométrique (ISO 15192:2021) Ionenchromatographie mit photometrischer Detektion
(ISO 15192:2021)
This European Standard was approved by CEN on 26 June 2021.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15192:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 15192:2021) has been prepared by Technical Committee ISO/TC 190 "Soil
quality" in collaboration with Technical Committee CEN/TC 444 “Environmental characterization of
solid matrices” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2022, and conflicting national standards shall
be withdrawn at the latest by January 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 15192:2006.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN websites.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 15192:2021 has been approved by CEN as EN ISO 15192:2021 without any modification.

INTERNATIONAL ISO
STANDARD 15192
Second edition
2021-06
Soil and waste — Determination
of Chromium(VI) in solid
material by alkaline digestion
and ion chromatography with
spectrophotometric detection
Déchets et sols — Dosage du chrome(VI) dans les matériaux solides
par digestion alcaline et chromatographie ionique avec détection
spectrophotométrique
Reference number
ISO 15192:2021(E)
©
ISO 2021
ISO 15192:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO 15192:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Safety remarks . 1
5 Principle . 2
5.1 Digestion. 2
5.2 Determination . 2
5.3 Interferences and sources of error . 2
6 Apparatus . 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 . 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 . . 8
10.5.4 Duplicate samples . 8
10.5.5 Soluble 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) Ion chromatographic system .11
Annex B (informative) Requirements for test portion preparation .13
Annex C (informative) Validation .14
Annex D (informative) Background on methods for the determination of Cr(VI) in solid samples 18
Bibliography .22
ISO 15192:2021(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, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 444, Environmental Characterization, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
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.
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 2021 – All rights reserved

ISO 15192:2021(E)
Introduction
Under environmental conditions chromium in compounds exists in the trivalent, Cr(III), or the
hexavalent, Cr(VI) state. Chromium 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 document.
INTERNATIONAL STANDARD ISO 15192:2021(E)
Soil and waste — Determination of Chromium(VI) in solid
material by alkaline digestion and ion chromatography
with spectrophotometric detection
1 Scope
This document specifies 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 8466-1, Water quality - Calibration and evaluation of analytical methods and estimation of performance
characteristics - Part 1: Statistical evaluation of the linear calibration function
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
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Safety remarks
Anyone dealing with waste and soil analysis shall 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, 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. It is presupposed that
national regulations are followed with respect to all hazards associated with this method.
ISO 15192:2021(E)
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:
a) digestion solution shall solubilize all species of Cr(VI);
b) conditions of the digestion shall not induce reduction of native Cr(VI) to Cr(III);
c) 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 soils and
wastes. Under the alkaline conditions of the digestion, negligible 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 minimises
[1][5][8]
air oxidation of trivalent chromium .
NOTE Background on methods for the determination of Cr(VI) in solid samples is given in Annex C.
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 (see Annex C).
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
[6]
the alkaline digestion solution from solid material .
— 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
[3]
Mn content and amended with soluble Cr(III) salts or freshly precipitated Cr(OH) .
— 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
[5]
alkaline digestion solution .
— Cr(III) can be oxidised to Cr(VI) in hot alkaline solutions. This problem is minimised in the described
[2][3][5][8]
procedure by adding magnesium to the alkaline digestion solution .
2 © ISO 2021 – All rights reserved

ISO 15192:2021(E)
— Overloading the analytical column capacity with high concentrations of anionic species (e.g.
[9]
chloride) may cause underestimation of Cr(VI) .
6 Apparatus
6.1 Digestion equipment.
6.1.1 Hotplate with a magnetic stirrer, thermostatically controlled with a digestion vessel of 250 ml
covered with a watch glass, or
6.1.2 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.
6.6.1 UV-VIS spectrophotometer, at 365 nm, or
6.6.2 VIS spectrophotometer, at 540 nm after post column derivatisation.
7 Reagents
7.1 General.
During the analysis, only use reagents of recognised analytical grade, and water as specified in 7.2.
7.2 Water.
-1
Water with an 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).
7.3 Sulphuric acid (H SO ), concentrated, ρ(H SO ) ~1,84 g/ml, w(H SO ) ~98 %.
2 4 2 4 2 4
7.4 Sodium carbonate (Na CO ), anhydrous, w(Na CO ) >9,9 %.
2 3 2 3
7.5 1,5-Diphenylcarbazide (C H N O), w(C H N O) >98 %; CAS RN 140-22-7.
13 14 4 13 14 4
ISO 15192:2021(E)
7.6 Propanone (acetone) (C H O).
3 6
7.7 Methanol (CH O).
7.8 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.
7.9 Sodium hydroxide (NaOH), w(NaOH) >99 %.
7.10 Magnesium chloride hexahydrate (MgCl ·6H O), w(MgCl ·6H O) >99 %.
2 2 2 2
7.11 Dipotassium hydrogenphosphate (K HPO ), w(K HPO ) >99 %.
2 4 2 4
7.12 Potassium dihydrogenphosphate (KH PO ), w(KH PO ) >99 %.
2 4 2 4
7.13 Lead chromate (PbCrO ), w(PbCrO ) >99 %.
4 4
7.14 Diphenylcarbazide reagent solution.
Dissolve 0,125 g of 1,5-diphenylcarbazide (7.5) in 25 ml of propanone (7.6) or methanol (7.7) in a
250 ml volumetric flask. Fill 125 ml of water into a separate container, slowly add 7 ml of concentrated
sulphuric acid (7.3), 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.
7.15 Eluent solution.
Use an eluent solution (see Annex A) appropriate to separate chromate over the ion chromatographic
column (6.5).
NOTE Eluents can be prepared manually by in-line dilution or electrochemically in situ.
7.16 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 (7.9) in approximately 500 ml of water (7.2). Add 30,0 g of sodium
carbonate (7.4) 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 to 12. Store in a polyethylene bottle at room temperature. This reagent is stable for one month.
7.17 Calibration solutions of Cr(VI).
7.17.1 Cr(VI) standard stock solution, 1 000 mg/l Cr(VI).
Dissolve 0,282 9 g of potassium dichromate (7.8) in 75 ml of water (7.2) in a 100 ml volumetric flask.
Dilute to the mark with water (7.2), close and mix thoroughly. Store the solution in a polypropylene
bottle. This reagent is stable for one year.
7.17.2 Cr(VI) working standard solution, 10 mg/l Cr(VI).
Pipette 10,0 ml of the Cr(VI) standard stock solution (7.17.1) into a 1 l volumetric flask, dilute to the
mark with water (7.2), close and mix thoroughly. This reagent is stable for one month.
4 © ISO 2021 – All rights reserved

ISO 15192:2021(E)
7.17.3 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 (7.16). Add 25 ml of the alkaline digestion solution (7.16) into
a 50 ml volumetric flask, pipette the appropriate volume of Cr(VI) working standard solution (7.17.2)
into the volumetric flask and dilute to the mark with water (7.2), close and mix thoroughly. Prepare
fresh solutions on the day of use.
7.17.4 Cr(VI) spiking solutions.
The Cr(VI) working standard solution (7.17.2) can be used to spike samples.
7.18 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 (7.11) and 68,04 g of KH PO (7.12) 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.
7.19 Magnesium chloride solution.
Dissolve 85,4 g MgCl ·6H O (7.10) in a 100 ml volumetric flask, dilute to the mark with water (7.2), close
2 2
and mix thoroughly.
7.20 Chromium chloride hexahydrate (CrCl .6H O), w(CrCl ·6H O) >96 %.
3 2 3 2
7.21 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 (7.20) in water
(7.2) in a 100 ml volumetric flask, dilute to the mark with water (7.2), close and mix thoroughly. Store
the solution in a polypropylene bottle. This reagent is stable for one year. Before using, determine the
Cr concentration of the spiking solution.
8 Sample pretreatment
Samples shall be collected using appropriate devices and placed in plastic or glass containers.
NOTE Requirements for test portion preparation are summarised in Annex B.
Samples shall be stored field moist at (4 ± 2) °C until analysis. Pre-treat the sample according to
EN 16179, ISO 11464 or EN 15002 if not otherwise specified.
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 shall be
avoided.
After digestion the sample shall be analysed as soon as possible.
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 digestion solution
[2]
for up to 7 days after digestion from soil .
ISO 15192:2021(E)
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 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 (7.16) to each sample using a graduated
cylinder, and also add 1 ml of magnesium chloride solution (7.19) containing approximately 400 mg of
MgCl and 0,5 ml of phosphate buffer solution (7.18). 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 with continuous stirring, then maintain the samples at
(92,5 ± 2,5) °C for at least (60 ± 5) min with 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 (7.2). Filter through
a 0,45 µm membrane filter (6.3). Rinse the filtration equipment (6.2) with water (7.2) and transfer the
filtrate to a 100 ml volumetric flask and fill up to the mark with water (7.2).
NOTE Alternatively the sample can be centrifuged or allowed to settle and fill up the mark with water.
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 is possible (see
Annex A).
10.2 Instrumental set-up
10.2.1 Set up the ion chromatograph in accordance with manufacturer’s instructions.
10.2.2 For post column derivatisation, optimise the ratio of eluent solution and reagent flow rates or
adjust the sulphuric acid concentration of the diphenylcarbazide reagent solution (7.14) to obtain the
best signal to background ratio. It is important that the ratio between the eluent solution and reagent
flow rates is kept constant, that the total flow rate does not exceed the maximum flow rate for the detector
and the diphenylcarbazide reagent is 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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ISO 15192:2021(E)
10.2.3 For direct detection, adjust the UV-VIS detector to measure within a range of 355 nm to 375 nm,
preferably at 365 nm.
For measuring after post-column derivatisation 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 (typically 20 µl to 250 µl), of each calibration solution (7.17.3) into the
ion chromatographic system (6.4).
10.3.2 Determine the absorbance for each of the calibration solutions using either peak height or peak
area mode.
10.3.3 Prepare a calibration graph using a linear plot of the peak height or peak area as a function of
calibration solution concentration by least squares regression analysis using suitable software, according
to ISO 8466-1.
10.4 Test solution measurement
10.4.1 Inject a suitable volume, e.g. 50 µl, of filtered sample solutions (9.2) into the ion chromatographic
system.
10.4.2 Determine the concentrations of Cr(VI) in the test solutions (9.2) by comparison with the
calibration graph (10.3.3).
10.4.3 If the Cr(VI) concentration of the sample exceeds the calibration range, dilute the sample with a
1 + 1 diluted alkaline digestion solution (7.16) and re-analyse. Take note of the dilution when calculating
the mass concentration of Cr(VI) in the material under investigation.
NOTE For samples expected to have very high concentrations of Cr(VI), it can be necessary to dilute the test
solutions before they are first analysed. Otherwise, swamping of the diphenylcarbazide reagent can occur and no
colour will develop.
If the chromium (VI) concentration of the sample falls lower than the calibration range, establish a
separate calibration function for the lower working range, if necessary.
10.5 Quality control
10.5.1 General
Process quality control (QC) samples with each batch of test samples, as detailed below.
10.5.2 Blank test solution
To assess glassware contamination and/or reagents, process in parallel at least one blank solution
following the same digestion procedure as applied to the test samples but omitting the test portion.
If contamination is detected control the procedure until the level of Cr(VI) is less than 0,5 times the
lowest concentration to be reported and repeat the digestions.
Analyse the blank solutions according to a frequency of 1 blank per 20 test portions or at least once in
each series of measurement.
ISO 15192:2021(E)
10.5.3 Verification of method
Prepare a soluble Cr(VI) standard solution from a stock standard solution from a different source than
that used for preparing the calibration solutions. In parallel with processing the test samples, prepare a
blank solution spiked with this soluble Cr(VI) standard solution following the same digestion procedure
as applied to the test samples but omitting the test portion. Recovery of Cr(VI) must be within range of
80 % to 120 %. Process this QC sample within each batch.
Alternatively, to evaluate the dissolution of all Cr(VI) species during the digestion process, an insoluble
spike, e.g. PbCrO (7.13), may be used. In parallel with processing the test samples, prepare a blank
solution spiked with , e.g., 20 mg of PbCrO following the same digestion procedure as applied to the
test samples but omitting the test portion. Recovery of Cr(VI) must be within range of 75 % to 120 %.
Prepare a Cr(III) standard solution from the Cr(III) spiking solution (7.21). In parallel with processing
the test samples prepare a blank solution spiked with this Cr(III) standard solution following the same
digestion procedure as applied to the test samples but omitting the test portion. Conversion of Cr(III) to
Cr(VI) shall be less than 5 %. Process this QC sample within each batch.
10.5.4 Duplicate samples
Process method duplicated samples to estimate the method accuracy according to a frequency of at
least 1 duplicate sample per 20 test portions or minimum of 1 per batch.
Duplicate samples must have a relative percent difference of <20%, if both the original and the duplicate
are greater than four times the laboratory reporting limit. A control limit of ± the laboratory reporting
limit is used when either the original or the duplicate sample is less than four times the laboratory
reporting limit.
10.5.5 Soluble Cr(VI) spiked samples
Process soluble spikes, e.g. K Cr O (7.17.4), on a routine basis to estimate the method accuracy in
2 2 7
relation to possible reduction processes. Spiked samples consist of solid material to which known
amounts of Cr(VI) have been added.
Soluble pre-digestion matrix spikes should be analyzed at a frequency of at least 1 spike sample per
20 test portions or 1 per batch. The matrix spike is then carried through the digestion process. More
frequent matrix spikes should be analysed if the sample characteristics within the analytical batch
appear to have significant variability based on visual observation. An acceptance range for matrix
spike recoveries is 75 % to 125 %.
10.5.6 Cr(III) spiked samples
Process the Cr(III) spiking solution (7.21) on a routine basis to estimate the method accuracy in relation
to the possible oxidation processes, expressed as a percent Cr(VI) recovery relative to the spiked
amount of Cr(III). Spiked samples consist of solid material to which known amounts of Cr(III) have been
added.
The conversion of the Cr(III) spike can be used to assess the risk of method induced oxidation of native
Cr(III) contained in the sample to Cr(VI) and shall be less than 5 %.
10.5.7 Interpretation of quality control data
If the verification procedure performed in 10.5.3 and the recoveries from the spiked samples performed
in 10.5.5 and 10.5.6 meet laboratory criteria, the analytical result can be judged to be valid.
NOTE 1 An acceptable range for Cr(VI) spike recoveries is 75 % to 125 % in soil, sludge, sediments and similar
[7]
waste materials according to EPA-method 3060 A .
8 © ISO 2021 – All rights reserved

ISO 15192:2021(E)
If the verification procedure performed in 10.5.3 meets the laboratory criteria, but the recoveries from
the spiked samples performed in 10.5.5 and 10.5.6 do not meet the laboratory criteria, it is appropriate
to determine the reducing/oxidising tendency of the sample matrix.
NOTE 2 This can be accomplished by characterisation of each sample for additional analytical parameters,
such as pH, ferrous iron (FeII), sulfides, organic carbon content and the oxidation potential. Analysis of these
additional parameters establishes the tendency of Cr(VI) to exist or not exist in the unspiked samples and assists
in interpreting QC data for matrix spike recoveries outside conventionally accepted criteria for total metals.
11 Calculation
Calculate the mass fraction of Cr(VI) in the solid waste material or soil, using Formula (1):
ρ ⋅⋅F 10
d
w = (1)
Cr VI
()
mw⋅
dm
where
w is the mass fraction of Cr(VI) in the solid material, expressed in milligram per kilogram
Cr(VI)
(mg/kg) dry matter;
ρ is the concentration of Cr(VI) in the alkaline digested test solution, expressed in micro-
d
gram per litre (μg/l);
m is the weight of the test portion, expressed in grams (g), nominally 2,5 g;
w is the dry matter content of the test portion, expressed as a percentage, determined as
dm
specified by ISO 11465 for soil and EN 15934 for waste;
F is the dilution factor (F = 1 if the alkaline digestion solution of nominally 100 ml has not
been diluted prior to analysis).
12 Expression of results
Values should be rounded to 0,01 mg/kg, only three significant figures should be expressed.
EXAMPLE:
w = 0,15 mg/kg
Cr(VI)
w = 15,3 mg/kg
Cr(VI)
13 Test report
Work carried out by the testing laboratory shall be covered by a report which accurately, clearly
and unambiguously presents the test results and all other relevant information as specified in
ISO/IEC 17025.
The test report shall include at least the following information:
a) a reference to this document (ISO 15192:2021);
b) identity of the sample;
c) expression of results according to Clause 12;
d) any deviation from this method;
ISO 15192:2021(E)
e) any details not specified in this document or which are optional, as well as any factor which may
have affected the results.
10 © ISO 2021 – All rights reserved

ISO 15192:2021(E)
Annex A
(informative)
Ion chromatographic system
Figure A.1 — Scheme of an ion chromatographic system configured for spectrophotometric
detection
An ion chromatography system (Figure A.1), in general, consists of the following components: - Eluent
reservoir;
The preparation of a typical eluent used for the seperation column is described by the following:
Ammonium sulfate/ammonium hydroxide eluent concentrate, 2,5 mol/l ammonium sulfate
(NH ) SO /0,5 mol/l ammonium hydroxide (NH OH). Dissolve 331 g of ammonium sulfate in
4 2 4 4
approximately 500 ml of water. Quantitatively transfer the solution into a 1 l one-mark volumetric
flask, add 75 ml of concentrated ammonium hydroxide and swirl to mix. Dilute to the mark with water,
stopper and mix thoroughly.
ISO 15192:2021(E)
Eluent solution, 0,25 mol/l ammonium sulfate (NH ) SO /0,05 mol/l ammonium hydroxide
4 2 4
(NH OH), pH 8. Add 100 ml of eluent concentrate to a 1 l one-mark volumetric flask, dilute to the mark
with water, stopper and mix thoroughly.
— Metal- free HPLC pump, 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;
— Sample injection system, incorporating a sample loop of appropriate volume or autosampler device;
— Guard and separator column, suitable for chromate separation with a sufficient ion exchange
capacity;
— Spectrophotometric detection system;
In case of direct determination, the IC column is directly coupled to the detector. In case of post
column derivatisation, the IC column is coupled to a mixing tee (reaction coil) and then connected
to the detector.
— UV-VIS spectrophotometer at 365 nm; or
— VIS spectrophotometer at 540 nm after post column derivatisation.
Data handling system, e.g. a computer with software for data acquisition and evaluatio
...