Plant biostimulants - Determination of specific elements - Part 3: Determination of mercury

This document specifies a method for determination of the content of mercury (Hg) in plant biostimulants using (cold) vapour generation apparatus coupled to an atomic absorption spectrophotometer and a method using a direct amalgamation technique. It is applicable to aqua regia digests prepared according to CEN/TS 17701-1.
NOTE    It is also possible to use other suitable methods for the determination of mercury described in Annex A if users prove that the method gives the same results as the methods described in this document.
This document is also applicable to the blends of fertilizing products where plant biostimulants are the main part of the blend. Otherwise, the Technical Specification for the main part of the blend applies.

Pflanzen-Biostimulanzien - Bestimmung spezifischer Elemente - Teil 3: Bestimmung von Quecksilber

Dieses Dokument legt ein Verfahren zur Bestimmung des Quecksilbergehalts (Hg) in Pflanzen-Biostimulanzien mittels eines Systems der (Kalt )Verdampfungstechnik, gekoppelt mit einem Atomabsorptionsspektrometer und einem Verfahren, das auf einer direkten Amalgamierungstechnik beruht, fest. Es ist für Königswasseraufschlüsse anwendbar, die nach CEN/TS 17701 1 hergestellt werden.
ANMERKUNG   Auch die Anwendung anderer, in Anhang A beschriebener, geeigneter Verfahren der Quecksilber-bestimmung ist möglich, sofern die Anwender nachweisen, dass das Verfahren zu gleichen Ergebnissen führt wie die in diesem Dokument beschriebenen Verfahren.
Dieses Dokument ist auch für die Mischungen von Düngeprodukten anwendbar, in denen die Pflanzen-Biostimulanzien der Hauptbestandteil der Mischung sind. Andernfalls gilt die Technische Spezifikation für den Hauptbestandteil der Mischung.

Biostimulants des végétaux - Dosage des éléments spécifiques - Partie 3 : Dosage du mercure

Le présent document spécifie une méthode pour la détermination de la teneur en mercure (Hg) dans les biostimulants des végétaux avec un appareil de génération de vapeur (à froid) couplé à un spectrophotomètre d’absorption atomique et une méthode utilisant une technique d’amalgamation directe. Il est applicable aux digestats à l’eau régale préparés conformément à la CEN/TS 17701-1.
NOTE Il est aussi possible d’utiliser d’autres méthodes adaptées pour le dosage du mercure décrites dans l’Annexe A, si l’utilisateur prouve que la méthode conduit aux mêmes résultats que les méthodes décrites dans le présent document.
Le présent document est également applicable aux mélanges de fertilisants dont la majeure partie est constituée de biostimulants des végétaux. Dans le cas contraire, la Spécification technique relative au constituant principal du mélange s’applique.

Rastlinski biostimulanti - Določevanje specifičnih elementov - 3. del: Določevanje živega srebra

Ta dokument določa metodo za določevanje vsebnosti živega srebra (Hg) v rastlinskih biostimulantih z uporabo naprave za ustvarjanje (hladne) pare, povezane z atomskim absorpcijskim spektrofotometrom, in metodo, ki uporablja tehniko neposredne amalgamacije. Uporablja se za izlužke zlatotopke, pripravljene v skladu s standardom CEN/TS 17701-1.
OPOMBA:    Možna je tudi uporaba drugih ustreznih metod za določanje živega srebra, opisanih v dodatku A, če uporabniki dokažejo, da izbrana metoda zagotavlja enake rezultate kot metode, opisane v tem dokumentu.
Dokument je uporaben tudi za mešanice sredstev za gnojenje, pri katerih so rastlinski biostimulanti glavni del mešanice. V nasprotnem primeru se uporablja tehnična specifikacija za glavni del mešanice.

General Information

Status
Published
Publication Date
22-Mar-2022
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
23-Mar-2022
Due Date
30-Aug-2022
Completion Date
23-Mar-2022

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SLOVENSKI STANDARD
SIST-TS CEN/TS 17701-3:2023
01-februar-2023
Rastlinski biostimulanti - Določevanje specifičnih elementov - 3. del: Določevanje
živega srebra
Plant biostimulants - Determination of specific elements - Part 3: Determination of
mercury
Pflanzen-Biostimulanzien - Bestimmung spezifischer Elemente - Teil 3: Bestimmung von
Quecksilber
Biostimulants des végétaux - Dosage des éléments spécifiques - Partie 3 : Dosage du
mercure
Ta slovenski standard je istoveten z: CEN/TS 17701-3:2022
ICS:
65.080 Gnojila Fertilizers
SIST-TS CEN/TS 17701-3:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST-TS CEN/TS 17701-3:2023

---------------------- Page: 2 ----------------------
SIST-TS CEN/TS 17701-3:2023


CEN/TS 17701-3
TECHNICAL SPECIFICATION

SPÉCIFICATION TECHNIQUE

March 2022
TECHNISCHE SPEZIFIKATION
ICS 07.080
English Version

Plant biostimulants - Determination of specific elements -
Part 3: Determination of mercury
Biostimulants des plantes - Détermination des Biostimulanzien für die pflanzliche Anwendung -
éléments spécifiques - Partie 3 : Détermination du Bestimmung spezifischer Elemente - Teil 3:
mercure Bestimmung von Quecksilber
This Technical Specification (CEN/TS) was approved by CEN on 3 January 2022 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17701-3:2022 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
SIST-TS CEN/TS 17701-3:2023
CEN/TS 17701-3:2022 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Interferences . 6
6 Reagents . 6
7 Apparatus . 7
8 Procedure. 8
9 Calculation and expression of the results . 9
10 Test report . 10
Annex A (informative) Methods for mercury determination . 11
Bibliography . 13

2

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SIST-TS CEN/TS 17701-3:2023
CEN/TS 17701-3:2022 (E)
European foreword
This document (CEN/TS 17701-3:2022) has been prepared by the Technical Committee CEN/TC 455
“Plant Biostimulants”, the secretariat of which is held by AFNOR.
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 has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
The CEN/TS 17701 series, Plant biostimulants — Determination of specific elements, consists of the
following parts:
— Part 1: Digestion by aqua regia for subsequent determination of elements;
— Part 2: Determination of total content of Cd, Pb, Ni, As, Cr, Cu and Zn;
— Part 3: Determination of mercury.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: 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.
3

---------------------- Page: 5 ----------------------
SIST-TS CEN/TS 17701-3:2023
CEN/TS 17701-3:2022 (E)
Introduction
This document was prepared by the experts of CEN/TC 455 “Plant Biostimulants”. The European
Committee for Standardization (CEN) was requested by the European Commission (EC) to draft
European standards or European standardization deliverables to support the implementation of
Regulation (EU) 2019/1009 of 5 June 2019 laying down rules on the making available on the market of
EU fertilizing products (“FPR” or “Fertilising Products Regulation”).
This standardization request, presented as M/564, also contributes to the Communication on “Innovating
for Sustainable Growth: A Bio economy for Europe”. The Working Group 4 “Other safety parameters”, was
created to develop a work program as part of this request. The Technical Committee CEN/TC 455 “Plant
Biostimulants” was established to carry out the work program that will prepare a series of standards. The
interest in biostimulants has increased significantly in Europe as a valuable tool to use in agriculture.
Standardization was identified as having an important role in order to promote the use of biostimulants.
The work of CEN/TC 455 seeks to improve the reliability of the supply chain, thereby improving the
confidence of farmers, industry, and consumers in biostimulants, and will promote and support
commercialisation of the European biostimulant industry.
The preparation of this document is based on a standardization request to CEN by the European
Commission and the European Free Trade Association (Mandate M/564) concerning the modernization
of methods of analysis of fertilizers in the framework of Regulation (EU) 2019/1009 of the European
Parliament and of the Council.
This document concerns the analytical measurement step for the determination of mercury in plant
biostimulants after digestion by aqua regia according to CEN/TS 17701-1. It covers cold vapour
generation followed by mercury determination using atomic absorption spectrophotometry (AAS).
Different cold vapour generation techniques can be used (flow injection, segmented flow, batch). This
document also includes a method based on a direct amalgamation technique which is widely used in
many analytical laboratories. It is also possible to use other suitable methods of mercury determination
described in Annex A if users prove that the methods give the same results as the methods described in
this document.
WARNING – Persons using this document should be familiar with usual laboratory practice. This
document does not purport to address all of the safety issues, if any, associated with its use. It is
the responsibility of the user to establish appropriate health and safety practices and to ensure
compliance with any national regulatory conditions.
IMPORTANT – It is absolutely essential that tests conducted according to this document are
carried out by suitably trained staff.
4

---------------------- Page: 6 ----------------------
SIST-TS CEN/TS 17701-3:2023
CEN/TS 17701-3:2022 (E)
1 Scope
This document specifies a method for determination of the content of mercury (Hg) in plant biostimulants
using (cold) vapour generation apparatus coupled to an atomic absorption spectrophotometer and a
method using a direct amalgamation technique. It is applicable to aqua regia digests prepared according
to CEN/TS 17701-1.
NOTE It is also possible to use other suitable methods for the determination of mercury described in Annex A
if users prove that the method gives the same results as the methods described in this document.
This document is also applicable to the blends of fertilizing products where plant biostimulants are the
main part of the blend. Otherwise, the Technical Specification for the main part of the blend applies.
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.
CEN/TS 17701-1, Plant biostimulants — Determination of specific elements — Part 1: Digestion by aqua
regia for subsequent determination of elements
CEN/TS 17704, Plant biostimulants — Determination of dry matter
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
digest
solution received after mineralization of the organic matter of a sample and dissolution of its mineral
part, more or less completely, when reacting with a reagent mixture
4 Principle
4.1 Vapour generation atomic absorption spectrophotometry (VG-AAS)
Mono- and divalent mercury is reduced to the elemental form by tin(II) chloride or sodium borohydride
in an acid medium. Elemental mercury is stripped off from the solution and determined in the form of an
atomic gas by an atomic absorption spectrophotometer.
4.2 Direct amalgamation (DA)
The sample is thermally decomposed in an oxygen rich environment. The decomposition products are
carried to an amalgamator that selectively traps mercury. After the system is flushed with oxygen to
remove any remaining gases or decomposition products, the amalgamator is rapidly heated, releasing
mercury vapour. Flowing oxygen carries the mercury vapour through absorbance cells positioned in the
light path of a single wavelength atomic absorption spectrophotometer. Absorbance is measured at
253,7 nm as a function of mercury concentration.
5

---------------------- Page: 7 ----------------------
SIST-TS CEN/TS 17701-3:2023
CEN/TS 17701-3:2022 (E)
5 Interferences
5.1 Vapour generation atomic absorption spectrophotometry (VG-AAS)
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, because sodium borohydride reduces many elements
commonly found in plant biostimulant digests to the elemental state, which may cause matrix problems
under particular circumstances. However, it is still possible to use sodium borohydride as a reduction
agent. The interferences due to the presence of other elements in the matrix depend on its concentrations.
Copper and nickel exceeding a concentration of 500 mg/l can cause a negative bias.
5.2 Direct amalgamation (DA)
Instruments with an amalgamation technique are very often used for a direct determination of mercury
in samples without a digestion step. Nevertheless, some solid samples (e.g. silicates or phosphates) may
not be fully thermally decomposed and therefore in this case or if an unknown sample is analysed, the
analysis of aqua regia digests is preferable. For plant biostimulants usually no difference is observed
between the direct determination of mercury and the determination of mercury after digestion in aqua
regia.
6 Reagents
6.1 Water with a specific conductivity not higher than 0,2 mS/m at 25 °C, free from mercury.
6.2 Carrier gas.
Argon or nitrogen for VG-AAS, oxygen for DA, purity according to the recommendation of the
manufacturer.
6.3 Hydrochloric acid, c(HCl) ≈ 12 mol/l, 37 % volume fraction, ρ approximately 1,18 g/ml.
6.4 Nitric acid, c(HNO ) ≈ 16 mol/l; not less than 65 % volume fraction; ρ approximately 1,42 g/ml.
3
6.5 Mixed acid solution of 0,8 mol/l nitric acid and 1,8 mol/l hydrochloric acid
Mix 150 ml of hydrochloric acid (6.3) and 50 ml nitric acid (6.4) with water (6.1) up to 1,0 l.
6.6 Reducing agents
Tin(II) chloride or sodium borohydride may be used as the reducing agent, but it is not advisable to use
the two reagents alternately. Follow the instructions of the manufacturers of the apparatus. The
concentration by mass of the reducing agent solutions may be varied to suit the system, and the relevant
information provided by the manufacturer of the apparatus shall be observed.
6.6.1 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 (6.3), transfer to a 100 ml volumetric flask
2 2
and fill to the mark with water (6.1). 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.
6

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SIST-TS CEN/TS 17701-3:2023
CEN/TS 17701-3:2022 (E)
6.6.2 Sodium borohydride solution, NaBH , ρ(NaBH ) = 30 g/l
4 4
1 g sodium hydroxide, NaOH, is weighed into a 100 ml volumetric flask and dissolved in water (6.1). 3 g
sodium borohydride, NaBH , are weighed into a 100 ml volumetric flask, dissolved and diluted to the
4
mark with the sodium hydroxide solution.
A solution of lower concentration, e.g. 3 g/l may be used with flow systems. Prepare this solution freshly
on the day of use from the more concentrated solution by diluting with water (6.1). Follow the
recommendations of the manufact
...

SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 17701-3:2021
01-november-2021
Rastlinski biostimulansi - Določevanje določenih elementov - 3. del: Določevanje
živega srebra
Plant biostimulants - Determination of specific elements - Part 3: Determination of
mercury
Biostimulanzien für die pflanzliche Anwendung - Bestimmung spezifischer Elemente -
Teil 3: Bestimmung von Quecksilber
Biostimulants des plantes - Détermination des éléments spécifiques - Partie 3 :
Détermination du mercure
Ta slovenski standard je istoveten z: FprCEN/TS 17701-3
ICS:
65.080 Gnojila Fertilizers
kSIST-TS FprCEN/TS 17701-3:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021

---------------------- Page: 2 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021


FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17701-3
SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION

September 2021
ICS 07.080
English Version

Plant biostimulants - Determination of specific elements -
Part 3: Determination of mercury
Biostimulants des plantes - Détermination des Biostimulanzien für die pflanzliche Anwendung -
éléments spécifiques - Partie 3 : Détermination du Bestimmung spezifischer Elemente - Teil 3:
mercure Bestimmung von Quecksilber


This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/TC 455.

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.

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 Technical Specification. It is distributed for review and comments. It is subject to change
without notice and shall not be referred to as a Technical Specification.


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. FprCEN/TS 17701-3:2021 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021
FprCEN/TS 17701-3:2021 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Interferences . 6
6 Reagents . 6
7 Apparatus . 7
8 Procedure. 8
9 Calculation and expression of the results . 9
10 Test report . 10
Annex A (informative) Methods for mercury determination . 11
A.1 Cold vapour generation (hydride generation) . 11
A.2 Direct amalgamation technique . 12
A.3 Inductively coupled plasma mass spectrometry (ICP-MS). 12
Bibliography . 13

2

---------------------- Page: 4 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021
FprCEN/TS 17701-3:2021 (E)
European foreword
This document (FprCEN/TS 17701-3:2021) has been prepared by the Technical Committee CEN/TC 455
“Plant Biostimulants”, the secretariat of which is held by AFNOR.
This document is currently submitted to the Vote on TS.
The CEN/TS 17701 series, Plant biostimulants - Determination of specific elements, consists of the
following parts:
— CEN/TS 17701-1, Plant biostimulants - Determination of specific elements - Part 1: Digestion by aqua
regia for subsequent determination of elements;
— CEN/TS 17701-2, Plant biostimulants - Determination of specific elements - Part 2: Determination of
total content of Cd, Pb, Ni, As, Cr, Cu and Zn;
— CEN/TS 17701-3, Plant biostimulants - Determination of specific elements - Part 3: Determination of
mercury.
3

---------------------- Page: 5 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021
FprCEN/TS 17701-3:2021 (E)
Introduction
This document was prepared by the experts of CEN/TC 455 ‘Plant Biostimulants’. The European
Committee for Standardization (CEN) was requested by the European Commission (EC) to draft
European standards or European standardization deliverables to support the implementation of
Regulation (EU) 2019/1009 of 5 June 2019 laying down rules on the making available on the market of
EU fertilising products (“FPR” or “Fertilising Products Regulation”).
This request, presented as SR M/564, also contributes to the Communication on “Innovating for
Sustainable Growth: A Bio economy for Europe”. The Working Group 4 “Other safety parameters”, was
created to develop a work program as part of this Request. The technical committee CEN/TC 455 ‘Plant
Biostimulants’ was established to carry out the work program that will prepare a series of standards. The
interest in biostimulants has increased significantly in Europe as a valuable tool to use in agriculture.
Standardization was identified as having an important role in order to promote the use of biostimulants.
The work of CEN/TC 455 seeks to improve the reliability of the supply chain, thereby improving the
confidence of farmers, industry, and consumers in biostimulants, and will promote and support
commercialisation of the European biostimulant industry.
The preparation of this document is based on a standardization request to CEN by the European
Commission and the European Free Trade Association (Mandate M/564) concerning the modernization
of methods of analysis of fertilizers in the framework of Regulation (EU) 2019/1009 of the European
Parliament and of the Council.
This document concerns the analytical measurement step for the determination of mercury in plant
biostimulants after digestion by aqua regia according to CEN/TS 17701-1. The standard covers cold
vapour generation followed by mercury determination using atomic absorption spectrophotometry
(AAS). Different cold vapour generation techniques can be used (flow injection, segmented flow, batch).
The standard also includes a method based on a direct amalgamation technique which is widely used in
many analytical laboratories. It is also possible to use other suitable methods of mercury determination
described in Annex A if users prove that the methods give the same results as the methods described in
the standard.
WARNING – Persons using this document should be familiar with usual laboratory practice. This
document does not purport to address all of the safety issues, if any, associated with its use. It is
the responsibility of the user to establish appropriate health and safety practices and to ensure
compliance with any national regulatory conditions.
IMPORTANT – It is absolutely essential that tests conducted according to this document are
carried out by suitably trained staff.
4

---------------------- Page: 6 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021
FprCEN/TS 17701-3:2021 (E)
1 Scope
This document specifies a method for determination of the content of mercury (Hg) in plant biostimulants
using (cold) vapour generation apparatus coupled to an atomic absorption spectrophotometer and a
method using a direct amalgamation technique. It is applicable to aqua regia digests prepared according
to CEN/TS 17701-1.
NOTE It is also possible to use other suitable methods for the determination of mercury described in Annex A
if users prove that the method gives the same results as the methods described in this document.
This document is also applicable to the blends of fertilizing products where plant biostimulants are the
main part of the blend. Otherwise, the Technical Specification for the main part of the blend applies.
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.
CEN/TS 17701-1, Plant biostimulants - Determination of specific elements - Part 1: Digestion by aqua regia
for subsequent determination of elements
CEN/TS 17704, Plant biostimulants - Determination of dry matter
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
digest
solution received after mineralization of the organic matter of a sample and dissolution of its mineral
part, more or less completely, when reacting with a reagent mixture
4 Principle
4.1 Vapour generation atomic absorption spectrophotometry (VG-AAS)
Mono- and divalent mercury is reduced to the elemental form by tin(II) chloride or sodium borohydride
in an acid medium. Elemental mercury is stripped off from the solution and determined in the form of an
atomic gas by an atomic absorption spectrophotometer.
4.2 Direct amalgamation (DA)
The sample is thermally decomposed in an oxygen rich environment. The decomposition products are
carried to an amalgamator that selectively traps mercury. After the system is flushed with oxygen to
remove any remaining gases or decomposition products, the amalgamator is rapidly heated, releasing
mercury vapour. Flowing oxygen carries the mercury vapour through absorbance cells positioned in the
light path of a single wavelength atomic absorption spectrophotometer. Absorbance is measured at
253,7 nm as a function of mercury concentration.
5

---------------------- Page: 7 ----------------------
kSIST-TS FprCEN/TS 17701-3:2021
FprCEN/TS 17701-3:2021 (E)
5 Interferences
5.1 Vapour generation atomic absorption spectrophotometry (VG-AAS)
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, because sodium borohydride reduces many elements
commonly found in plant biostimulant digests to the elemental state, which may cause matrix problems
under particular circumstances. However, it is still possible to use sodium borohydride as a reduction
agent. The interferences due to the presence of other elements in the matrix depend on its concentrations.
Copper and nickel exceeding a concentration of 500 mg/l may cause a negative bias.
5.2 Direct amalgamation (DA)
Instruments with an amalgamation technique are very often used for a direct determination of mercury
in samples without a digestion step. Nevertheless, some solid samples (e.g. silicates or phosphates) may
not be fully thermally decomposed and therefore in this case or if an unknown sample is analysed, the
analysis of aqua regia digests is preferable. For plant biostimulants usually no difference is observed
between the direct determination of mercury and the determination of mercury after digestion in aqua
regia.
6 Reagents
6.1 Water with a specific conductivity not higher than 0,2 mS/m at 25 °C, free from mercury.
6.2 Carrier gas.
Argon or nitrogen for VG-AAS, oxygen for DA, purity according to the recommendation of the
manufacturer.
6.3 Hydrochloric acid, c(HCl) ≈ 12 mol/l; 37 % volume fraction; ρ approximately 1,18 g/ml.
6.4 Nitric acid, c(HNO ) ≈ 16 mol/l; not less than 65 % volume fraction; ρ approximately
3
1,42 g/ml.
6.5 Mixed acid solution of 0,8 mol/l nitric acid and 1,8 mol/l hydrochloric acid
Mix 150 ml of hydrochloric acid (6.3) and 50 ml nitric acid (6.4) to 1,0 l of water (6.1).
6.6 Reducing agents
Tin(II) chloride or sodium borohydride may be used as the reducing agent, but it is not advisable to use
the two reagents alternately. Follow the instructions of the manufacturers of the apparatus. The
concentration by mass of the reducing agent solutions may be varied to suit the system, and the relevant
information provided by the manufacturer of the apparatus shall be observed.
6.6.1 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 (6.3), transfer to a 100 ml volumetric flask
2 2
and fill to the mark with water (6.1). 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.
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kSIST-TS FprCEN/TS 17701-3:2021
FprCEN/TS 17701-3:2021 (E)
6.6.2 Sodium borohydride solution, NaBH , ρ(NaBH ) = 30 g/l
4 4
1 g sodium hydroxide, NaOH, is weighed into a 100 ml volumetric flask and dissolved in water (6.1). 3 g
sodium borohydride, NaBH , are weighed into a 100 ml volumetric flask, dissolved and diluted to the
4
mark with the sodium hydroxide solution.
A solution of lower concentration, e.g. 3 g/l may be used with flow systems. Prepare this solution freshly
on the day of use from the more concentrated solution by diluting with water (6.1). Follow the
recommendations of the manufacturer of the instrument.
WARNING – It is essential to observe the safety instructions for working with sodium borohydride.
Sodium borohydride forms hydrogen with acids and this can result in an explosive air/hydrogen mixture.
A permanent fume extraction system shall be
...

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