oSIST prEN 16175-1:2026

• Abstract:

  This European Standard specifies a method for the determination of mercury in digests of soil, treated biowaste and waste, obtained according to EN ISO 54321 (aqua regia digestion) or EN 16173 (nitric acid digestion) or EN 13656 (digestion with a hydrochloric, nitric and tetrafluoroboric or hydrofluoric acid mixture) using cold-vapour atomic absorption spectrometry (CV-AAS). The lower working range limit is at least 0,03 mg/kg (drymatter basis) depending on digestion parameters.

• Status: Not Published
• Public Enquiry End Date: 01-Nov-2026
• ICS: 13.030.20 - Liquid wastes. Sludge
• ICS: 13.080.01 - Soil quality and pedology in general
• ICS: 13.080.10 - Chemical characteristics of soils
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: KAT - Soil quality
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 16-Sep-2026
• Due Date: 03-Feb-2027
• Ref Project: prEN 16175-1 - Soil, treated biowaste and sludge - Determination of mercury - Part 1: Cold-vapour atomic absorption spectrometry (CV-AAS)

• Revises: SIST EN 16175-1:2017 - Sludge, treated biowaste and soil - Determination of mercury - Part 1: Cold-vapour atomic absorption spectrometry (CV-AAS)
• Effective Date: 01-Oct-2026

oSIST prEN 16175-1:2026 is the Slovenian adoption of draft European Standard prEN 16175-1 from SIST/CEN. It specifies a method for determining mercury in digests of soil, treated biowaste, sludge and waste by cold-vapour atomic absorption spectrometry (CV-AAS). In practice, it is the document a laboratory uses when it needs a defined mercury test for these environmental solid matrices, with a lower working range limit of at least 0.03 mg/kg on a dry-matter basis depending on digestion parameters.

What does oSIST prEN 16175-1:2026 specify?

oSIST prEN 16175-1:2026 specifies the CV-AAS method for mercury in digests prepared by defined acid digestion routes. The method is intended for particle-free digest or extraction solutions and is tied to the digestion step, because the result depends on how the sample was brought into solution.

The document is organized into clauses on scope, principle, interferences, reagents, apparatus, procedure, calculation and expression of results, performance data, and test report, followed by an informative validation annex.

Annex	What it covers
Annex A	Repeatability and reproducibility data from an interlaboratory comparison

What are the key requirements of oSIST prEN 16175-1:2026?

The method in oSIST prEN 16175-1:2026 is built around a controlled digestion, chemical reduction of mercury, gas-phase separation, and optical measurement at a fixed wavelength. For a user, the main practical point is that both the digestion route and the measurement setup have to stay consistent if results are to be comparable.

Digestion and test solution

The method applies to digests prepared according to EN 16173, EN ISO 54321, or EN 13656. The test solution is taken from the particle-free digest or extraction solution, and it must be diluted so the influence of digestion reagents is reduced.

Measurement principle

Mercury in the solution is reduced to the elemental form with tin(II) chloride or sodium borohydride in acid medium, stripped into a closed system, and measured by CV-AAS at 253.7 nm. Tin(II) chloride is the preferred reducing agent; sodium borohydride is allowed, but it can create more matrix effects with some samples.

Interferences and matrix control

The document notes that strong oxidizing digestion acids remove organic interferences in the gas phase. It also gives tolerable concentrations for selected matrix elements, including Cu(II), Ni(II) and Ag(I); exceeding these levels may bias the result low. In practice, this means sample chemistry has to be checked if results look suspicious.

Reagents and apparatus

Reagents and water must be suitable for trace analysis, and carrier gas is argon or nitrogen of at least 99.99 % purity. The document describes both usual laboratory apparatus and automated mercury flow systems, as well as manually operated or semi-automated batch systems. If a flow system is used, the reducing-agent concentration, reaction time and separator configuration need optimization.

Calibration and blanks

Before each batch, the user prepares a calibration blank and at least five calibration solutions covering the expected range. A test blank is prepared in parallel with the sample using the same reagents but no test solution. This is important because the reported mercury content is corrected for the blank signal.

Calculation and reporting

Results are calculated from the difference between test solution and test blank, corrected for dilution and dry matter fraction. The dry matter correction uses EN ISO 11465. Results are reported with no more than three significant figures, which keeps reporting aligned with the precision of the method.

Performance and test report

The document includes performance data in Annex A and requires a test report with the standard reference, date, sample identification, digestion information, result and any deviations or factors affecting the result.

What terms does oSIST prEN 16175-1:2026 define?

• Cold-vapour atomic absorption spectrometry (CV-AAS) - The measurement technique used here, where reduced mercury vapour is passed through the light path of an atomic absorption spectrometer.
• Atomic absorption spectrometer (AAS) - The instrument that measures absorbance at 253.7 nm to quantify mercury vapour.
• Flow injection analysis (FIA) - An automated continuous-flow setup mentioned for mercury determination, used to improve throughput and sensitivity.
• Tin(II) chloride - The recommended reducing reagent that converts ionic mercury to elemental mercury.
• Sodium borohydride - An alternative reducing reagent allowed by the method, though it may cause more matrix effects.
• Test blank solution - A blank prepared with the same reagents and procedure as the sample, but without the test solution.
• Calibration blank solution - The zero-level solution used when building the calibration curve.

Who uses oSIST prEN 16175-1:2026?

oSIST prEN 16175-1:2026 is used by laboratories that test soil, sludge, treated biowaste and waste for mercury. That includes environmental testing labs, municipal and industrial sludge laboratories, and contract labs supporting waste, soil and biowaste monitoring.

The document also matters to quality managers and buyers who need a defined analytical method for specifications, acceptance checks, monitoring programs or compliance-related testing. The warning and introduction make clear that the work should be done by trained staff familiar with normal laboratory practice.

What changed in oSIST prEN 16175-1:2026 from the previous edition?

This draft will supersede EN 16175-1:2016. The foreword states these significant technical changes:

• EN ISO 54321 and EN 13656 were added to the scope.
• EN 16174 was removed.
• The calibration range and stabilization reagents were opened to user choice.
• Clause 6 on apparatus was revised.

Which standards are used with oSIST prEN 16175-1:2026?

The document names related standards and uses them for sample preparation, reporting and precision work:

• EN 16173 - nitric acid digestion for test solutions.
• EN ISO 54321 - aqua regia digestion for test solutions.
• EN 13656 - digestion with hydrochloric, nitric and tetrafluoroboric or hydrofluoric acid mixture.
• EN ISO 11465 - dry matter fraction used in the final correction.
• ISO 5725-2 - statistical basis used for the repeatability and reproducibility study in Annex A.
• EN 16175-2 - the companion part of the mercury series using CV-AFS.

What does the oSIST prEN 16175-1:2026 document contain?

The document contains the full analytical workflow: the measurement principle, interference guidance, reagents, apparatus, sample and blank preparation, calibration, measurement, calculation and reporting. It also gives practical setup details for both manual and automated systems, including wavelength, gas flow, reaction conditions and the handling of calibration solutions.

Annex A adds validated performance data from an interlaboratory comparison on sludge, compost and soil materials. The bibliography points to the digestion standards, dry matter standard and precision standard that support the method.

SLOVENSKI STANDARD
01-oktober-2026
Tla, obdelani biološki odpadki in blato - Določanje živega srebra - 1. del: Metoda
atomske absorpcijske spektrometrije s tehniko hladnih par (CV-AAS)
Soil, treated biowaste and sludge - Determination of mercury - Part 1: Cold-vapour
atomic absorption spectrometry (CV-AAS)
Schlamm, behandelter Bioabfall und Boden - Bestimmung von Quecksilber - Teil 1:
Kaltdampf-Atomabsorptionsspektrometrie (CV-AAS)
Boues, bio-déchets traités et sols - Détermination du mercure - Partie 1: Spectrométrie
d'absorption atomique de vapeur froide (SAA-VP)
Ta slovenski standard je istoveten z: prEN 16175-1
ICS:
13.030.20 Tekoči odpadki. Blato Liquid wastes. Sludge
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.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2026
ICS 13.080.10 Will supersede EN 16175-1:2016
English Version
Soil, treated biowaste and sludge - Determination of
mercury - Part 1: Cold-vapour atomic absorption
spectrometry (CV-AAS)
Sols, biodéchets traités et boues - Détermination du Schlamm, behandelter Bioabfall und Boden -
mercure - Partie 1: Spectrométrie d'absorption Bestimmung von Quecksilber - Teil 1: Kaltdampf-
atomique à vapeur froide (SAA VF) Atomabsorptionsspektrometrie (CV-AAS)
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 444.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, Türkiye and
United Kingdom.
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.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16175-1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Interferences . 5
6 Reagents . 6
7 Apparatus . 7
7.1 Usual laboratory apparatus . 7
7.2 Automated system with sample introduction, cold-vapour generator, flow injection
analysis and atom absorption spectrometer . 7
8 Procedure . 8
8.1 Test solution . 8
8.2 Test blank solution . 8
8.3 Preparation of the calibration solutions . 8
8.4 Instrumental set-up . 8
8.5 Calibration . 8
8.6 Measurement of test sample . 8
9 Calculation and expression of results . 9
9.1 Calculation . 9
9.2 Expression of results . 9
10 Performance data . 9
11 Test report . 10
Annex A (informative) Repeatability and reproducibility data . 11
Bibliography . 13

European foreword
This document (prEN 16175-1:2026) has been prepared by Technical Committee CEN/TC 444 “Test
methods for environmental characterization of solid matrices”, the secretariat of which is held by NEN.
This document is currently submitted to the-CEN Enquiry.
This document will supersede EN 16175-1:2016.
prEN 16175:2026 includes the following significant technical changes with respect to EN 16175-1:2016:
— EN ISO 54321 and EN 13656 digestion standards were added to the scope and EN 16174 is removed.
—- Calibration range and stabilization reagents were opened to customer belongings.
— Clause 6 Apparatus has been revised.
EN 16175, Sludge, treated biowaste and soil — Determination of mercury comprises the following parts:
— Part 1: Cold-vapour atomic absorption spectrometry (CV-AAS);
— Part 2: Cold-vapour atomic fluorescence spectrometry (CV-AFS).
Introduction
This document is applicable and validated for several types of matrices as indicated in Table 1 (see
Annex A for the results of validation).
Table 1 — Matrices for which this document is applicable and validated
Matrix Materials used for validation
Sludge Municipal sludge
Biowaste Compost
Soil Soil
WARNING — Persons using this document should be familiar with usual laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It
is the responsibility of the user to establish appropriate safety and health practices and to ensure
compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted according to this document be
carried out by suitably trained staff.
1 Scope
This document specifies a method for the determination of mercury in digests of soil, treated biowaste,
sludge and waste, obtained according to EN 16173 (nitric acid digestion), EN ISO 54321 (aqua regia
digestion) or EN 13656 (digestion with a hydrochloric (HCl), nitic (HNO ) and tetrafluoroboric (HBF ) or
3 4
hydrofluoric (HF) acid mixture) with using cold-vapour atomic absorption spectrometry (CV-AAS). The
lower working range limit is at least 0,03 mg/kg (dry matter basis) depending on digestion parameters.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
4 Principle
Mono- and divalent mercury is reduced to the elemental form by tin(II) chloride or sodium borohydride
in acid medium. Elemental mercury is stripped off from the solution in a closed system. The mercury
vapour, in the form of an atomic gas, passes through a cell positioned in the light path of an atomic
absorption spectrometer. Its absorbance at a wavelength of 253,7 nm is measured. The absorbance signal
is a function of mercury concentration, and the concentrations are calculated using a calibration curve.
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 document, because sodium borohydride reduces many
elements commonly found in soil, sludge and waste extract solutions, to the elemental state, which might
cause matrix problems under particular circumstances. However, it is still possible to use sodium
borohydride as reduction agent.
5 Interferences
Because the samples are digested with oxidizing, strong acids before determination of mercury starts,
there are no interferences with organic substances in the gas phase that can absorb in the UV range.
Neither are there any interferences with mercury compounds which cannot be fully reduced with tin(II)
chloride alone. The interferences due to the presence of other elements in the matrix depend on their
concentrations. Element concentrations exceeding those listed in Table 2 may cause negative bias.
Fewer 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 2.
Table 2 — Tolerable concentrations of some matrix elements
Element Acceptable
concentration in the test
solution
mg/l
Cu(II) 500
Ni(II) 500
Ag(I) 1
6 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 of mercury to be determined.
−1
6.1 Water, with an electrical conductivity less than 0,1 mS m (equivalent to resistivity greater than
0,01 MΩ m at 25°C). For all sample preparations and dilutions.
6.2 Carrier gas, argon or nitrogen, with a purity of ≥ 99,99 %.
6.3 Hydrochloric acid, HCl, ρ(HCl) = 1,15 g/ml - 1,18 g/ml, w(HCl) = 300 g/kg - 370 g/kg.
The same batch of hydrochloric acid shall be used throughout the procedure.
6.4 Nitric acid, HNO3, ρ(HNO3) = 1,4 g/ml, w(HNO3) = 650 g/kg.
The same batch of nitric acid shall be used throughout the procedure.
6.5 Nitric acid, diluted solution.
Dilute the digestion reagents (EN 16173) in the same way as the test solutions are diluted.
6.6 Nitric acid, c(HNO3) = 2 mol/l, rinsing solution for glassware.
Add 150 ml of nitric acid (6.4) to ab
...