Organic and organo-mineral fertilizers - Determination of the mercury content

This document specifies a method for determination of the content of mercury (Hg) in organic fertilizers and organo-mineral fertilizers 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 17768.
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 standard.

Organische und organisch-mineralische Düngemittel - Bestimmung des Quecksilbergehaltes

Dieses Dokument legt ein Verfahren zur Bestimmung des Quecksilbergehalts (Hg) in organischen Dünge¬mitteln und organisch-mineralischen Düngemitteln mittels eines Systems der (Kalt )Dampftechnik, gekoppelt mit einem Atomabsorptionsspektrometer und einem Verfahren, das auf einer direkten Amalgamierungs¬technik beruht, fest. Es ist anzuwenden für Königswasseraufschlüsse, die nach CEN/TS 17768 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 dieser Norm beschriebenen Verfahren.

Engrais organiques et organo-minéraux - Détermination de la teneur en mercure

Le présent document spécifie une méthode pour la détermination de la teneur en mercure (Hg) dans les engrais organiques et organo-minéraux 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 17768.
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 la présente norme.

Organska in organsko-mineralna gnojila - Določevanje živega srebra

Ta dokument vzpostavlja metodologijo za določevanje živega srebra.

General Information

Status
Published
Publication Date
05-Apr-2022
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
06-Apr-2022
Due Date
04-Feb-2023
Completion Date
06-Apr-2022

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SLOVENSKI STANDARD
SIST-TS CEN/TS 17769:2023
01-februar-2023
Organska in organsko-mineralna gnojila - Določevanje živega srebra
Organic and organo-mineral fertilizers - Determination of the mercury content
Organische und organisch-mineralische Düngemittel - Bestimmung des
Quecksilbergehaltes
Engrais organiques et organo-minéraux - Détermination de la teneur en mercure
Ta slovenski standard je istoveten z: CEN/TS 17769:2022
ICS:
65.080 Gnojila Fertilizers
SIST-TS CEN/TS 17769:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN/TS 17769:2023

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SIST-TS CEN/TS 17769:2023


CEN/TS 17769
TECHNICAL SPECIFICATION

SPÉCIFICATION TECHNIQUE

April 2022
TECHNISCHE SPEZIFIKATION
ICS 65.080
English Version

Organic and organo-mineral fertilizers - Determination of
the mercury content
Engrais organiques et organo-minéraux - Organische und organisch-mineralische Düngemittel -
Détermination de la teneur en mercure Bestimmung des Quecksilbergehaltes
This Technical Specification (CEN/TS) was approved by CEN on 13 March 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 17769:2022 E
worldwide for CEN national Members.

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SIST-TS CEN/TS 17769:2023
CEN/TS 17769:2022 (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 . 5
6 Reagents . 6
7 Apparatus . 7
8 Procedure. 7
9 Calculation and expression of the results . 9
10 Test report . 10
Annex A (informative) Methods for mercury determination . 11
A.1 General . 11
A.2 Cold vapour generation (hydride generation) . 11
A.3 Direct amalgamation technique . 12
A.4 Inductively coupled plasma mass spectrometry (ICP-MS). 12
Bibliography . 13

2

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SIST-TS CEN/TS 17769:2023
CEN/TS 17769:2022 (E)
European foreword
This document (CEN/TS 17769:2022) has been prepared by Technical Committee CEN/TC 260
“Fertilizers and liming materials”, the secretariat of which is held by DIN.
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.
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

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SIST-TS CEN/TS 17769:2023
CEN/TS 17769:2022 (E)
Introduction
This document concerns the analytical measurement step for the determination of mercury in organic
fertilizers and organo-mineral fertilizers after digestion by aqua regia according to CEN/TS 17768. The
document 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 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.
4

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SIST-TS CEN/TS 17769:2023
CEN/TS 17769:2022 (E)
1 Scope
This document specifies a method for determination of the content of mercury (Hg) in organic
fertilizers and organo-mineral fertilizers 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 17768.
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 standard.
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 17773, Organic and organo-mineral fertilizers — Determination of the dry matter 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:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
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 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 organic fertilizers and organo-mineral fertilizers digests to the elemental state,
which can 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
5

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SIST-TS CEN/TS 17769:2023
CEN/TS 17769:2022 (E)
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. samples with a very high
silicates or phosphate content) might 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 organic fertilizers
and organo-mineral fertilizers 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 General
The concentration of mercury in the reagents and in water shall be negligible compared to the lowest
concentration of mercury to be determined. Reagents in 6.2, 6.6 and 6.7 are used only for the VG-AAS
method.
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, substance concentration c(HCl) ≈ 12 mol/l; 37 % volume fraction; mass
concentration 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, 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 800 ml of water (6.1).
WARNING – For safety reasons the acid has to be poured into the water.
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. 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.
6.6.2 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. 3 g
sodium borohydride, NaBH4, are weighed into a 100 ml volumetric flask, dissolved and diluted to the
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. Follow the
recommendations of the manufacturer of the instrument.
6

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SIST-TS CEN/TS 17769:2023
CEN/TS 17769:2022 (E)
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 provided at the point where measurements are
carried out.
6.7 Standard (stock) solutions
6.7.1 Standard stock solution, ρ = 1 000 mg/l.
Use commercially available mercury stock solution with adequate specification, stating the acid used
and the preparation technique. The solution is considered to be stable for more than one year, but in
reference to guaranteed stability, see the recommendations of the manufacturer. Alternatively, the
stock solutions may be prepared by the dissolution of high purity metal mercury or its salts.
6.7.2 Standard solution I, ρ = 100 mg/l.
Pipette 10 ml of the mercury standard stock solution (6.7.1) into a 100 ml volumetric flask. Add 10 ml of
nitric acid (6.4), fill to the mark with water and mix well. This solution is stable for one month.
6.7.3 Standard solution II, ρ = 1 mg/l.
Pipette 1 ml of mercury standard solution I (6.7.2) into a 100 ml volumetric flask. Add 10 ml of nitric
acid (6.4) fill to the mark with water and mix well. This solution is stable for 7 days.
6.7.4 Standard solution III, ρ = 100 µg/l.
Pipette 10 ml
...

SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 17769:2021
01-december-2021
Organska in organsko-mineralna gnojila - Določevanje živega srebra
Organic and organo-mineral fertilizers - Determination of the mercury content
Organische und organisch-mineralische Düngemittel - Bestimmung des
Quecksilbergehaltes
Ta slovenski standard je istoveten z: FprCEN/TS 17769
ICS:
65.080 Gnojila Fertilizers
kSIST-TS FprCEN/TS 17769:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
kSIST-TS FprCEN/TS 17769:2021

---------------------- Page: 2 ----------------------
kSIST-TS FprCEN/TS 17769:2021


FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17769
SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION

November 2021
ICS 65.080
English Version

Organic and organo-mineral fertilizers - Determination of
the mercury content
 Organische und organisch-mineralische Düngemittel -
Bestimmung des Quecksilbergehaltes


This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/TC 260.

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 17769:2021 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
kSIST-TS FprCEN/TS 17769:2021
FprCEN/TS 17769:2021 (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 . 5
6 Reagents . 6
7 Apparatus . 7
8 Procedure. 7
9 Calculation and expression of the results . 9
10 Test report . 10
Annex A (informative) Methods for mercury determination . 11
A.1 General . 11
Figure A.1 — Diagram of possibilities for the mercury determination . 11
A.2 Cold vapour generation (hydride generation) . 11
A.3 Direct amalgamation technique . 12
A.4 Inductively coupled plasma mass spectrometry (ICP-MS). 12
Bibliography . 13
2

---------------------- Page: 4 ----------------------
kSIST-TS FprCEN/TS 17769:2021
FprCEN/TS 17769:2021 (E)
European foreword
This document (FprCEN/TS 17769:2021) has been prepared by Technical Committee CEN/TC 260
“Fertilizers and liming materials”, the secretariat of which is held by DIN.
This document is currently submitted on the Vote on TS.
This document has been prepared under a standardization request given to CEN by the European
Commission and the European Free Trade Association.
3

---------------------- Page: 5 ----------------------
kSIST-TS FprCEN/TS 17769:2021
FprCEN/TS 17769:2021 (E)
Introduction
This document concerns the analytical measurement step for the determination of mercury in organic
fertilizers and organo-mineral fertilizers after digestion by aqua regia according to FprCEN/TS 17768.
The document 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 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.
4

---------------------- Page: 6 ----------------------
kSIST-TS FprCEN/TS 17769:2021
FprCEN/TS 17769:2021 (E)
1 Scope
This document specifies a method for determination of the content of mercury (Hg) in organic
fertilizers and organo-mineral fertilizers 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 FprCEN/TS 17768.
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 standard.
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.
FprCEN/TS 17773, Organic and organo-mineral fertilizers — Determination of the dry matter 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 https://www.electropedia.org/
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 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 organic fertilizers and organo-mineral fertilizers 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
5

---------------------- Page: 7 ----------------------
kSIST-TS FprCEN/TS 17769:2021
FprCEN/TS 17769:2021 (E)
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. samples with a very high
silicates or phosphate content) 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 organic fertilizers
and organo-mineral fertilizers 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 General
The concentration of mercury in the reagents and in water shall be negligible compared to the lowest
concentration of mercury to be determined. Reagents in 6.2, 6.6 and 6.7 are used only for the VG-AAS
method.
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, substance concentration c(HCl) ≈ 12 mol/l; 37 % volume fraction; mass
concentration 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, 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 800 ml of water (6.1).
WARNING - For safety reasons the acid has to be poured into the water.
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. 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.
6.6.2 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. 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.
6

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kSIST-TS FprCEN/TS 17769:2021
FprCEN/TS 17769:2021 (E)
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. 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 provided at the point where measurements are
carried out.
6.7 Standard (stock) solutions
6.7.1 Standard stock solution, ρ = 1 000 mg/l.
Use commercially available mercury stock solution with adequate specification, stating the acid used
and the preparation technique. The solution is considered to be stable for more than one year, but in
reference to guaranteed stability, see the recommendations of the manufacturer. Alternatively, the
stock solutions may be prepared by the dissolution of high purity metal mercury or its salts.
6.7.2 Standard solution I, ρ = 100 mg/l.
Pipette 10 ml of the mercury standard stock solution (6.7.1) into a 100 ml volumetric flask. Add 10 ml of
nitric acid (6.4), fill to the mark with water and mix well. This solution is stable for one month.
6.7.3 Standard solution II, ρ = 1 mg/l.
Pipette 1 ml of mercury standard solution I (6.7.2) into a 100 ml volumetric flask. Add 10 ml of nitric
acid (6.4) fill to the mark with water and mix well. This solution is stable for 7 days.
6.7.4 Standard solution III, ρ = 100 µg/l.
Pipette 10 ml of mercury standard solution II (6.7.3) into a 100 ml volumetric flask. Add 10 ml of nitric
acid (6.4) fill to the mark with water and mix well. This solution shall be freshly prepared on the day of
use.
7 Apparatus
The instruments in 7.2 and 7.3 are used for VG-AAS method.
7.1 Common laboratory glassware.
7.2 Atomic absorption spectrophotometer, equipped with a heated quartz cell and an element
specific la
...

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