ISO/TS 16727:2013

TECHNICAL ISO/TS
SPECIFICATION 16727
First edition
2013-09-15
Corrected version
2013-10-01
Soil quality — Determination of
mercury — Cold vapour atomic
fluorescence spectrometry (CVAFS)
Qualité du sol — Dosage du mercure — Spectrométrie de fluorescence
atomique à vapeur froide (CVAFS)
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Interferences . 1
5 Reagents . 2
6 Apparatus . 3
6.1 Usual laboratory apparatus . 3
6.2 Atomic fluorescence spectrometer (AFS) . 3
6.3 Automated sample introduction system . 3
7 Procedure. 4
7.1 Test sample solution . 4
7.2 Test blank solution . 4
7.3 Preparation of the calibration solutions . 4
7.4 Calibration . 4
7.5 Measurement of test sample . 4
8 Calculation and expression of results . 5
8.1 Calculation . 5
8.2 Expression of results . 5
9 Test report . 5
Bibliography . 6
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical
methods and soil characteristics.
In this corrected version, the status of the document was amended to Technical Specification on the
cover page. In addition, the page headings were changed to ISO/TS 16727:2013(E).
iv © ISO 2013 – All rights reserved

Introduction
ISO/TS 16727 is based upon CEN/TS 16175-2, Sludge, treated biowaste and soil — Determination of
mercury — Part 2: Cold vapour atomic fluorescence spectrometry (CV-AFS), which was developed by
CEN/TC 400, Project Committee — Horizontal standards in the fields of sludge, biowaste and soil.
TECHNICAL SPECIFICATION ISO/TS 16727:2013(E)
Soil quality — Determination of mercury — Cold vapour
atomic fluorescence spectrometry (CVAFS)
WARNING — Persons using this Technical Specification should be familiar with usual laboratory
practice. This Technical Specification does not purport to address all of the safety problems, if
any, associated with its use. It is the responsibility of the user to establish appropriate safety and
health practices and to ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted according to this Technical
Specification be carried out by suitably trained staff.
1 Scope
This Technical Specification specifies a method for the determination of mercury in aqua regia or nitric
acid digests of sludge, treated biowaste and soil, obtained according to ISO 11466 or ISO 16729 using cold
vapour atomic fluorescence spectrometry. The lower working range limit is 0,003 mg/kg (dry matter).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 11465, Soil quality — Determination of dry matter and water content on a mass basis — Gravimetric method
ISO 11466, Soil quality — Extraction of trace elements soluble in aqua regia
ISO 16729, Soil quality — Digestion of nitric acid soluble fractions of elements
ISO 3696, Water for analytical laboratory use — Specification and test methods
3 Principle
Monovalent and divalent mercury is reduced to the elemental form by tin(II)-chloride solution or sodium
borohydride in acid medium. Elemental mercury is stripped off from the solution in a closed system,
by means of a stream of argon or nitrogen. The mercury vapour is injected into the cell of an atomic
fluorescence spectrometer where the mercury atoms are excited by radiation of a specific wavelength,
usually about 254 nm. The intensity of the fluorescence radiation is a function of mercury concentration.
The concentrations are calculated using a calibration curve.
NOTE The matrix of the solution analysed is dominated by the acids used in the digestion step. Tin(II)-chloride
as a reduction substance is recommended in this Technical Specification, because sodium borohydride reduces
many elements commonly found in soil, sludge and waste extract solutions, to the elemental state, which may
cause matrix problems under particular circumstances. However, it is still possible to use sodium borohydride as
reduction agent. The concentration range 0,1 µg/l to 10 µg/l in the digested solution, corresponding to 0,003 µg/g
to 0,3 µg/g of mercury, when a 3,0 g of sample has been digested, can be determined directly. Higher concentrations
can be determined if the digested solution is diluted. Sensitivity can be increased by the amalgamation technique.
4 Interferences
The presence of water vapour or aerosol in the fluorescence cell may cause suppression due to
quenching. Water vapour should be removed from the carrier gas stream using a hygroscopic membrane
before entering the detector. The noble metals, such as gold and silver, amalgamate with mercury and,
therefore, may cause suppression. Also anions, for instance sulfide, iodide and bromide, which complex
strongly with mercury, can cause suppression.
Less interferences arise from heavy metals when tin(II)chloride is used rather than sodium borohydride.
When flow systems are used, interference effects due to heavy metals may be less than indicated in Table 1.
Table 1 — Tolerable concentrations of some matrix elements
Element Acceptable concentration
mg/l
Cu(II) 500
Ni(II) 500
Ag(I) 1
5 Reagents
For the determination of mercury at trace and ultra-trace level, the reagents shall be of adequate
purity. The concentration of mercury or interfering substances in the reagents and the water should be
negligible compared to the lowest concentration to be determined.
5.1 Water quality 2 according to ISO 3696 for all sample preparations and dilutions.
5.2 Hydrochloric acid, HCl, ρ(HCl) ≈ 1,17 g/ml, c(HCl) ≈ 12 mol/l, w(HCl) ≈ 370 g/kg.
The same batch of hydrochloric acid shall be used throughout the procedure.
5.3 Nitric acid, HNO , ρ(HNO ) ≈ 1,4 g/ml, c(HNO ) ≈ 15 mol/l w(HNO ) ≈ 650 g/kg.
3 3 3 3
The same batch of nitric acid shall be used throughout the procedure.
5.4 Nitric acid, diluted solution (1 + 9).
Add 100 ml of nitric acid (5.3) to 500 ml of water in a 1 000 ml volumetric flask, mix and fill to the
mark with water
5.5 Nitric acid, rinsing solution for glassware, ≈ 2 mol/l.
Add 150 ml of nitric acid (5.3) to about 500 ml of water, and dilute with water to 1 000 ml.
5.6 Aqua regia, diluted solution (1 + 9).
Add 21 ml of hydrochloric acid (5.2) and 7 ml of nitric acid (5.3) to 500 ml of water in a 1 000 ml volumetric
flask, mix and fill to the mark with water.
5.7 Tin(II)chloride solution, ρ(SnCl ∙2 H O) = 100 g/l.
2 2
Dissolve 10 g of SnCl ∙2 H O in 30 ml of hydrochloric acid (5.2), transfer to a 100 ml volumetric flask and
2 2
fill to the mark with water. The blank concentration of mercury can be reduced by bubbling a stream of
nitrogen through the solution for 30 min, if necessary. Prepare this solution on the day of use.
A solution of lower concentration, e.g. 0,5 g in 100 ml, may be used with flow systems. Prepare this latter
solution freshly on the day of use from the more concentrated solution by diluting with water.
2 © ISO 2013 – All rights reserved

5.8 Sodium borohydride solution, NaBH , 30 g/l.
1 g of sodium hydroxide, NaOH, is weighed into a 100 ml volumetric flask and dissolved in water. 3 g of
sodium borohydride, NaBH , is weighed and dissolved in the sodium hydroxide solution, then diluted to
the mark with water.
5.9 Mercury standard stock solution, 1 000 mg/l
Use a commercially available quantitative stock solution with a mercury concentration of (1 000 ± 2) mg/l.
This solution is considered to be stable for at least one year, but in reference to guaranteed stability, see
the recommendations of the manufacturer.
...