Foodstuffs - Determination elements and their chemical species - Determination of organomercury in seafood by elemental mercury analysis

This document describes a method for the determination of organomercury in seafood/fishery products by elemental mercury analysis. The method has been successfully valideted in an interlaboratory study with a working range from 0,013 mg/kg to 5,12 mg/kg (HORRAT values <2) in seafood/fishery products [1], [2]. The limit of quantification is approximately 0,010 mg/kg organomercury (referring to dry weight, expressed as mercury) [3], [4].
Organic species of mercury, other than monomethylmercury, are also extracted and thus determined with this method. However, in seafood/fishery products the contribution from organic species of mercury other than monomethylmercury is negligible.

Lebensmittel - Bestimmung von Elementen und ihren Verbindungen - Bestimmung von Organoquecksilber in Fisch- und Meeresfrüchten mit Feststoffquecksilberbestimmung

Dieses Dokument legt ein Verfahren zur Bestimmung von Organoquecksilber in Fisch und Meeresfrüchten durch Nutzung eines Quecksilber Feststoff Analysators fest. Das Verfahren wurde in einem Ringversuch an Austerngewebe, Muschelgewebe, Hummer Hepatopankreas, Hundshaileber und Thunfisch mit Mengen von 0,01 mg/kg bis 5 mg/kg (bezogen auf das Trockengewicht und als Quecksilber ausgedrückt) erfolgreich validiert [1], [2].
Die Bestimmungsgrenze liegt bei etwa 0,01 mg/kg Organoquecksilber[3], [4].
Andere organische Quecksilberspezies als Monomethylquecksilber werden ebenfalls extrahiert und somit mit diesem Verfahren bestimmt. Bei Fisch und Meeresfrüchten ist der Beitrag anderer organischer Quecksilberspezies neben Monomethylquecksilber jedoch vernachlässigbar.

Produits alimentaires - Dosage des éléments et de leurs espèces chimiques - Dosage du mercure organique dans les fruits de mer par analyse du mercure élémentaire

La présente Norme européenne spécifie une méthode de dosage du mercure organique dans les produits
de la mer par analyse du mercure élémentaire. La méthode a été validée au cours d’un essai
interlaboratoires sur du tissu d’huître, du tissu de moule, de l’hépatopancréas de homard, du foie de
roussette et du thon à des niveaux allant de 0,01 mg/kg à 5 mg/kg faisant référence au poids sec et
exprimés en tant que mercure [1], [2].
La limite de quantification est d’environ 0,01 mg/kg de mercure organique [3], [4].
Les espèces organiques du mercure, autres que le monométhylmercure, sont également extraites et ainsi
dosées avec cette méthode. Cependant, dans les produits de la mer, la contribution des espèces
organiques du mercure autres que le monométhylmercure est négligeable.

Živila - Določevanje elementov in njihovih kemijskih oblik - Določevanje organskih živosrebrovih spojin v morski hrani z analizo elementarnega živega srebra

Ta dokument opisuje metodo za določanje organskega živega srebra v morskih /ribiških proizvodih z elementarno analizo živega srebra. Metoda je bila uspešno potrjena v medlaboratorijski študiji z delovnim obsegom od 0,013 mg/kg do 5,12 mg/kg (vrednosti HORRAT < 2) v morskih sadežih/ribiških proizvodih [1], [2]. Meja količinskega določanja je približno 0,010 mg/kg organskega živega srebra (ki se navezuje na suho maso, izraženo kot živo srebro) [3], [4]. Organske vrste živega srebra, razen monometilnega živega srebra, se tudi ekstrahirajo in tako določijo s to metodo. Vendar pa je v morskih/ribiških proizvodih prispevek organskih vrst živega srebra, razen monometilnega živega srebra, zanemarljiv.

General Information

Status
Published
Public Enquiry End Date
09-Oct-2018
Publication Date
10-Dec-2019
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
21-Nov-2019
Due Date
26-Jan-2020
Completion Date
11-Dec-2019

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SLOVENSKI STANDARD
SIST EN 17266:2020
01-januar-2020

Živila - Določevanje elementov in njihovih kemijskih oblik - Določevanje organskih

živosrebrovih spojin v morski hrani z analizo elementarnega živega srebra

Foodstuffs - Determination elements and their chemical species - Determination of

organomercury in seafood by elemental mercury analysis
Lebensmittel - Bestimmung von Elementen und ihren Verbindungen - Bestimmung von

Organoquecksilber in Fisch- und Meeresfrüchten mit Feststoffquecksilberbestimmung

Produits alimentaires - Dosage des éléments et de leurs espèces chimiques - Dosage du

mercure organique dans les fruits de mer par analyse du mercure élémentaire
Ta slovenski standard je istoveten z: EN 17266:2019
ICS:
67.120.30 Ribe in ribji proizvodi Fish and fishery products
SIST EN 17266:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 17266:2020
---------------------- Page: 2 ----------------------
SIST EN 17266:2020
EN 17266
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2019
EUROPÄISCHE NORM
ICS 67.120.30
English Version
Foodstuffs - Determination elements and their chemical
species - Determination of organomercury in seafood by
elemental mercury analysis

Produits alimentaires - Dosage des éléments et de leurs Lebensmittel - Bestimmung von Elementen und ihren

espèces chimiques - Dosage du mercure organique Verbindungen - Bestimmung von Organoquecksilber in

dans les produits de la mer par analyse du mercure Fisch und Meeresfrüchten mittels Elementaranalyse

élémentaire von Quecksilber
This European Standard was approved by CEN on 9 September 2019.

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

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17266:2019 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

1 Scope .................................................................................................................................................................... 4

2 Normative references .................................................................................................................................... 4

3 Terms and definitions ................................................................................................................................... 4

4 Principle ............................................................................................................................................................. 4

5 Reagents ............................................................................................................................................................. 5

6 Apparatus and equipment ........................................................................................................................... 8

7 Procedure........................................................................................................................................................... 8

7.1 Sample preparation ........................................................................................................................................ 8

7.2 Reagent blank solution ................................................................................................................................. 8

7.3 Determination by elemental mercury analyser ................................................................................... 8

7.4 Instrumental parameters ............................................................................................................................. 9

7.5 Analytical sequence ........................................................................................................................................ 9

8 Quality control ................................................................................................................................................. 9

8.1 Recovery ............................................................................................................................................................. 9

8.2 Instrument verification .............................................................................................................................. 10

8.3 Calibration curve .......................................................................................................................................... 10

8.4 Absence of contamination ......................................................................................................................... 11

9 Evaluation ....................................................................................................................................................... 11

9.1 Calculation ...................................................................................................................................................... 11

9.2 Expression of results ................................................................................................................................... 11

10 Precision .......................................................................................................................................................... 11

10.1 General ............................................................................................................................................................. 11

10.2 Repeatability .................................................................................................................................................. 11

10.3 Reproducibility ............................................................................................................................................. 11

11 Test report ...................................................................................................................................................... 12

Annex A (informative) Precision data ............................................................................................................... 13

Bibliography ................................................................................................................................................................. 15

---------------------- Page: 4 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
European foreword

This document (EN 17266:2019) has been prepared by Technical Committee CEN/TC 275 “Food

analysis - Horizontal methods”, the secretariat of which is held by DIN.

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 May 2020, and conflicting national standards shall be

withdrawn at the latest by May 2020.

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.

According to the CEN-CENELEC Internal Regulations, the national standards organisations 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.
---------------------- Page: 5 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
1 Scope

This document specifies a method for the determination of organomercury in seafood by elemental

mercury analysis. The method has been successfully validated in an interlaboratory study on oyster

tissue, mussel tissue, lobster hepatopancreas, dogfish liver and tuna at levels from 0,01 mg/kg to

5 mg/kg referring to dry weight and expressed as mercury [1], [2].

The limit of quantification is approximately 0,01 mg/kg of organomercury [3], [4].

Organic species of mercury, other than monomethylmercury, are also extracted and thus determined

with this method. However, in seafood the contribution from organic species of mercury other than

monomethylmercury is negligible.
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.

EN 13804, Foodstuffs - Determination of elements and their chemical species - General considerations and

specific requirements

EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696)

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 http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4 Principle

Organomercury in seafood/fishery products is separated from the matrix by double liquid-liquid

extraction, first with an organic solvent (toluene) and subsequently with L-cysteine solution and is

determined by elemental mercury analyser [3], [4].

Elemental mercury analyser, also known as automated or direct mercury analyser, is a single purpose

atomic absorption spectrophotometer for mercury determination. The determination of mercury with

an elemental mercury analyser is based on sample drying and subsequent thermal decomposition,

including electro thermal atomisation of mercury. A gold amalgamator selectively traps and pre-

concentrates the mercury from the flow of decomposition products. Finally, the trapped mercury is

thermally released and detected by atomic absorption at 253,7 nm. Organomercury results are

expressed in mg/kg as mercury.

Alternative detection techniques can be used, provided that equivalence of method performance is

proven.
---------------------- Page: 6 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
5 Reagents

The mass concentration of mercury in the reagents and water used shall be low enough not to affect the

results. All reagents shall be of analytical grade, i.e. pro analysis, p.a. or similar unless otherwise

specified.
Use water conforming to grade 2 of EN ISO 3696.

5.1 Nitric acid, mass fraction, w (HNO ) = 65 % (m/m), density approximately 1,4 g/ml

5.2 Hydrochloric acid, w (HCl) = 32 % (m/m), density approximately 1,18 g/ml
5.3 Diluted hydrochloric acid solution
Mix equal volumes of hydrochloric acid (5.2) and water.

5.4 Hydrobromic acid, w (HBr) approximately 47 %, density approximately 1,47 g/ml

5.5 Toluene
5.6 L-cysteine monohydrate hydrochloride, e.g. Ph. Eur. or USP grade
5.7 Sodium sulfate anhydrous
5.8 Sodium acetate anhydrous
5.9 L-cysteine solution, mass concentration ρ = 1 g/100 ml

Weigh 1,0 g of L-cysteine monohydrate hydrochloride (5.6), 12,5 g of sodium sulfate (5.7) and 0,8 g of

sodium acetate (5.8) into a 100 ml beaker. Add about 75 ml of water and stir until complete dissolution.

Transfer this solution completely to a 100 ml volumetric flask and make up to volume with water. This

solution can be stored for 1 day at ambient temperature. Other preparation volumes may be used as

long as proportions are kept.

The mass concentration of mercury in the L-cysteine solution should be as low as possible. The purity of

this solution should be such that the response for mercury shall be less than half the response of the

1 µg/l mercury standard solution (calibration solution 1, see 5.13).

L-cysteine precipitates on the catalytic tube which should thus be changed or cleaned as appropriate.

5.10 Mercury stock solution, ρ(Hg) = 1 000 mg/l Hg
5.11 Monomethylmercury (MMHg) chloride, minimum purity of 95 %
5.12 Mercury standard solutions
5.12.1 Mercury standard solution 1 (ρ = 10 mg/l Hg)

Pipette 1,0 ml of the commercial mercury stock solution 1 000 mg/l Hg (5.10) in a 100 ml volumetric

flask, add 2,0 ml of diluted hydrochloric acid solution (5.3) and make up to volume with water. This

solution is stable in a glass container in the refrigerator at approximately 2 °C to 10 °C for 6 months.

5.12.2 Mercury standard solution 2 (ρ = 0,50 mg/l Hg)
Ph. Eur. = European Pharmacopoeia; USP = United States Pharmacopoeia.
---------------------- Page: 7 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)

Pipette 2,5 ml of mercury standard solution 1 (5.12.1) in a 50 ml volumetric flask, add 1,0 ml of diluted

hydrochloric acid solution (5.3) and make up to volume with water. This solution is stable in a glass

container in the refrigerator at approximately 2 °C to 10 °C for 2 months.
5.13 Calibration solutions

Due to the highly stable response of elemental mercury analysers, there is no need to recalibrate for

each analytical sequence. Calibration is usually stable for at least 1 year. For that reason every

instrumental calibration will be maintained for that period, provided that quality controls for each

sequence are satisfactory. Nevertheless, if the gold amalgamator or catalyst tube is changed, response

could change and a new calibration is necessary. In such a case, analyse 500 µl of each calibration

solution (from blank to 100 µg/l Hg). For selection of corresponding calibration solutions for each

calibration curve, see 7.4. For acceptance criteria regarding the calibration curve, see 8.3.

Select calibration solutions depending on the cell used, thus on the expected concentration level of the

sample. This is comprehensively described in 7.4.
Prepare all calibration solutions freshly for each calibration.

Other volumes of preparation are suitable provided that they maintain the proportions described

below. Pipette either mercury standard solution 2 (5.12.2) or calibration solution 7 (see Table 1) in a

50 ml volumetric flask and fill up to the mark with L-cysteine solution (5.9) according to the scheme

presented in Table 1.
Use L-cysteine solution (5.9) as blank (level 0) for calibration.
Table 1 — Example of calibration solutions
Volume of initial Final Hg
Calibration solution
solution concentration (ρ)
Initial solution
ml µg/l
0 L-cysteine solution (5.9) 50 0
1 calibration solution no 7 1,0 1,0
2 calibration solution no 7 2,5 2,5
3 standard solution 2 (5.12.2) 0,5 5,0
4 standard solution 2 (5.12.2) 1,0 10
5 standard solution 2 (5.12.2) 1,5 15
6 standard solution 2 (5.12.2) 2,5 25
7 standard solution 2 (5.12.2) 5,0 50
8 standard solution 2 (5.12.2) 7,5 75
9 standard solution 2 (5.12.2) 10,0 100
---------------------- Page: 8 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
5.14 Internal quality control solutions
5.14.1 General

As the response of elemental mercury analysers is highly stable, there is no need to recalibrate the

instrument for each analytical sequence. However, some control solutions are used to ensure the

validity of the latest calibration. Each calibration curve needs to be compared against an external

solution to demonstrate absence of error in intermediate calibration s
...

SLOVENSKI STANDARD
SIST EN 17266:2020
01-januar-2020

Živila - Določevanje elementov in njihovih kemijskih oblik - Določevanje organskih

živosrebrovih spojin v morski hrani z analizo elementarnega živega srebra

Foodstuffs - Determination elements and their chemical species - Determination of

organomercury in seafood by elemental mercury analysis
Lebensmittel - Bestimmung von Elementen und ihren Verbindungen - Bestimmung von

Organoquecksilber in Fisch- und Meeresfrüchten mit Feststoffquecksilberbestimmung

Produits alimentaires - Dosage des éléments et de leurs espèces chimiques - Dosage du

mercure organique dans les fruits de mer par analyse du mercure élémentaire
Ta slovenski standard je istoveten z: EN 17266:2019
ICS:
67.120.30 Ribe in ribji proizvodi Fish and fishery products
SIST EN 17266:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 17266:2020
---------------------- Page: 2 ----------------------
SIST EN 17266:2020
EN 17266
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2019
EUROPÄISCHE NORM
ICS 67.120.30
English Version
Foodstuffs - Determination elements and their chemical
species - Determination of organomercury in seafood by
elemental mercury analysis

Produits alimentaires - Dosage des éléments et de leurs Lebensmittel - Bestimmung von Elementen und ihren

espèces chimiques - Dosage du mercure organique Verbindungen - Bestimmung von Organoquecksilber in

dans les produits de la mer par analyse du mercure Fisch und Meeresfrüchten mittels Elementaranalyse

élémentaire von Quecksilber
This European Standard was approved by CEN on 9 September 2019.

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

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17266:2019 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

1 Scope .................................................................................................................................................................... 4

2 Normative references .................................................................................................................................... 4

3 Terms and definitions ................................................................................................................................... 4

4 Principle ............................................................................................................................................................. 4

5 Reagents ............................................................................................................................................................. 5

6 Apparatus and equipment ........................................................................................................................... 7

7 Procedure........................................................................................................................................................... 8

7.1 Sample preparation ........................................................................................................................................ 8

7.2 Reagent blank solution ................................................................................................................................. 8

7.3 Determination by elemental mercury analyser ................................................................................... 8

7.4 Instrumental parameters ............................................................................................................................. 9

7.5 Analytical sequence ........................................................................................................................................ 9

8 Quality control ................................................................................................................................................. 9

8.1 Recovery ............................................................................................................................................................. 9

8.2 Instrument verification .............................................................................................................................. 10

8.3 Calibration curve .......................................................................................................................................... 10

8.4 Absence of contamination ......................................................................................................................... 11

9 Evaluation ....................................................................................................................................................... 11

9.1 Calculation ...................................................................................................................................................... 11

9.2 Expression of results ................................................................................................................................... 11

10 Precision .......................................................................................................................................................... 11

10.1 General ............................................................................................................................................................. 11

10.2 Repeatability .................................................................................................................................................. 11

10.3 Reproducibility ............................................................................................................................................. 11

11 Test report ...................................................................................................................................................... 12

Annex A (informative) Precision data ............................................................................................................... 13

Bibliography ................................................................................................................................................................. 15

---------------------- Page: 4 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
European foreword

This document (EN 17266:2019) has been prepared by Technical Committee CEN/TC 275 “Food

analysis - Horizontal methods”, the secretariat of which is held by DIN.

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 May 2020, and conflicting national standards shall be

withdrawn at the latest by May 2020.

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.

According to the CEN-CENELEC Internal Regulations, the national standards organisations 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.
---------------------- Page: 5 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
1 Scope

This document specifies a method for the determination of organomercury in seafood by elemental

mercury analysis. The method has been successfully validated in an interlaboratory study on oyster

tissue, mussel tissue, lobster hepatopancreas, dogfish liver and tuna at levels from 0,01 mg/kg to

5 mg/kg referring to dry weight and expressed as mercury [1], [2].

The limit of quantification is approximately 0,01 mg/kg of organomercury [3], [4].

Organic species of mercury, other than monomethylmercury, are also extracted and thus determined

with this method. However, in seafood the contribution from organic species of mercury other than

monomethylmercury is negligible.
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.

EN 13804, Foodstuffs - Determination of elements and their chemical species - General considerations and

specific requirements

EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696)

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 http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4 Principle

Organomercury in seafood/fishery products is separated from the matrix by double liquid-liquid

extraction, first with an organic solvent (toluene) and subsequently with L-cysteine solution and is

determined by elemental mercury analyser [3], [4].

Elemental mercury analyser, also known as automated or direct mercury analyser, is a single purpose

atomic absorption spectrophotometer for mercury determination. The determination of mercury with

an elemental mercury analyser is based on sample drying and subsequent thermal decomposition,

including electro thermal atomisation of mercury. A gold amalgamator selectively traps and pre-

concentrates the mercury from the flow of decomposition products. Finally, the trapped mercury is

thermally released and detected by atomic absorption at 253,7 nm. Organomercury results are

expressed in mg/kg as mercury.

Alternative detection techniques can be used, provided that equivalence of method performance is

proven.
---------------------- Page: 6 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)
5 Reagents

The mass concentration of mercury in the reagents and water used shall be low enough not to affect the

results. All reagents shall be of analytical grade, i.e. pro analysis, p.a. or similar unless otherwise

specified.
Use water conforming to grade 2 of EN ISO 3696.

5.1 Nitric acid, mass fraction, w (HNO ) = 65 % (m/m), density approximately 1,4 g/ml

5.2 Hydrochloric acid, w (HCl) = 32 % (m/m), density approximately 1,18 g/ml
5.3 Diluted hydrochloric acid solution
Mix equal volumes of hydrochloric acid (5.2) and water.

5.4 Hydrobromic acid, w (HBr) approximately 47 %, density approximately 1,47 g/ml

5.5 Toluene
5.6 L-cysteine monohydrate hydrochloride, e.g. Ph. Eur. or USP grade
5.7 Sodium sulfate anhydrous
5.8 Sodium acetate anhydrous
5.9 L-cysteine solution, mass concentration ρ = 1 g/100 ml

Weigh 1,0 g of L-cysteine monohydrate hydrochloride (5.6), 12,5 g of sodium sulfate (5.7) and 0,8 g of

sodium acetate (5.8) into a 100 ml beaker. Add about 75 ml of water and stir until complete dissolution.

Transfer this solution completely to a 100 ml volumetric flask and make up to volume with water. This

solution can be stored for 1 day at ambient temperature. Other preparation volumes may be used as

long as proportions are kept.

The mass concentration of mercury in the L-cysteine solution should be as low as possible. The purity of

this solution should be such that the response for mercury shall be less than half the response of the

1 µg/l mercury standard solution (calibration solution 1, see 5.13).

L-cysteine precipitates on the catalytic tube which should thus be changed or cleaned as appropriate.

5.10 Mercury stock solution, ρ(Hg) = 1 000 mg/l Hg
5.11 Monomethylmercury (MMHg) chloride, minimum purity of 95 %
5.12 Mercury standard solutions
5.12.1 Mercury standard solution 1 (ρ = 10 mg/l Hg)

Pipette 1,0 ml of the commercial mercury stock solution 1 000 mg/l Hg (5.10) in a 100 ml volumetric

flask, add 2,0 ml of diluted hydrochloric acid solution (5.3) and make up to volume with water. This

solution is stable in a glass container in the refrigerator at approximately 2 °C to 10 °C for 6 months.

5.12.2 Mercury standard solution 2 (ρ = 0,50 mg/l Hg)
Ph. Eur. = European Pharmacopoeia; USP = United States Pharmacopoeia.
---------------------- Page: 7 ----------------------
SIST EN 17266:2020
EN 17266:2019 (E)

Pipette 2,5 ml of mercury standard solution 1 (5.12.1) in a 50 ml volumetric flask, add 1,0 ml of diluted

hydrochloric acid solution (5.3) and make up to volume with water. This solution is stable in a glass

container in the refrigerator at approximately 2 °C to 10 °C for 2 months.
5.13 Calibration solutions

Due to the highly stable response of elemental mercury analysers, there is no need to recalibrate for

each analytical sequence. Calibration is usually stable for at least 1 year. For that reason every

instrumental calibration will be maintained for that period, provided that quality controls for each

sequence are satisfactory. Nevertheless, if the gold amalgamator or catalyst tube is changed, response

could change and a new calibration is necessary. In such a case, analyse 500 µl of each calibration

solution (from blank to 100 µg/l Hg). For selection of corresponding calibration solutions for each

calibration curve, see 7.4. For acceptance criteria regarding the calibration curve, see 8.3.

Select calibration solutions depending on the cell used, thus on the expected concentration level of the

sample. This is comprehensively described in 7.4.
Prepare all calibration solutions freshly for each calibration.

Other volumes of preparation are suitable provided that they maintain the proportions described

below. Pipette either mercury standard solution 2 (5.12.2) or calibration solution 7 (see Table 1) in a

50 ml volumetric flask and fill up to the mark with L-cysteine solution (5.9) according to the scheme

presented in Table 1.
Use L-cysteine solution (5.9) as blank (level 0) for calibration.
Table 1 — Example of calibration solutions
Volume of initial Final Hg
Calibration solution
solution concentration (ρ)
Initial solution
ml µg/l
0 L-cysteine solution (5.9) 50 0
1 calibration solution no 7 1,0 1,0
2 calibration solution no 7 2,5 2,5
3 standard solution 2 (5.12.2) 0,5 5,0
4 standard solution 2 (5.12.2) 1,0 10
5 standard solution 2 (5.12.2) 1,5 15
6 standard solution 2 (5.12.2) 2,5 25
7 standard solution 2 (5.12.2) 5,0 50
8 standard solution 2 (5.12.2) 7,5 75
9 standard solution 2 (5.12.2) 10,0 100
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SIST EN 17266:2020
EN 17266:2019 (E)
5.14 Internal quality control solutions
5.14.1 General

As the response of elemental mercury analysers is highly stable, there is no need to recalibrate the

instrument for each analytical sequence. However, some control solutions are used to ensure the

validity of the latest calibration. Each calibration curve needs to be compared against an external

solution to demonstrate absence of error in intermediate calibration solutions preparation.

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