Fertilizers - Determination of trace elements - Determination of mercury by vapour generation (VG) after aqua regia dissolution

This document specifies a method for the determination of the content of mercury in fertilizers after extraction with aqua regia and detection of mercury by vapour generation (VG) coupled to an atomic absorption spectrometer or an inductively coupled plasma atomic emission spectrometer. A limit of quantification of 0,01 mg/kg is to be expected.

Düngemittel und Calcium-/Magnesium-Bodenverbesserungsmittel - Bestimmung von Elementspuren - Bestimmung von Quecksilber mit Verdampfungstechnik (VG) nach Königswasseraufschluss

Diese Technische Spezifikation legt ein Verfahren zur Bestimmung von Quecksilber in Düngemitteln mittels Verdampfungstechnik (VG), gekoppelt mit Atomabsorptionsspektrometer oder Atomemissionsspektrometer mit induktiv gekoppeltem Plasma nach Königswasseraufschluss fest. Die Bestimmungsgrenze wird bei 0,01 mg/kg erwartet.

Engrais - Dosage des éléments traces - Détermination du mercure par génération de vapeur (VG) après digestion à l'eau régale

Cette spécification technique spécifie une méthode permettant de déterminer, après extraction à l’eau régale,
la teneur en mercure dans les engrais par détection de mercure par génération de vapeur (VG) couplée à un
spectromètre d’absorption atomique ou un spectromètre d’émission atomique avec plasma à couplage
inductif. Une limite de quantification de 0,01 mg/kg doit être attendue.

Gnojila - Določevanje elementov v sledovih - Določevanje živega srebra s tehniko hladnih par po raztapljanju v zlatotopki

Ta tehnična specifikacija določa metodo za določevanje vsebnosti živega srebra v gnojilih po ekstrakciji z zlatotopko in določevanje živega srebra s tehniko hladnih par (VG) z atomskim absorpcijskim spektrometrom ali atomskim emisijskim spektrometrom z induktivno sklopljeno plazmo. Pričakuje se meja kvantifikacije 0,01 mg/kg.

General Information

Status
Withdrawn
Public Enquiry End Date
19-Dec-2011
Publication Date
17-May-2012
Withdrawal Date
11-Nov-2013
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
12-Nov-2013
Due Date
05-Dec-2013
Completion Date
12-Nov-2013

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SLOVENSKI STANDARD
SIST-TS CEN/TS 16320:2012
01-junij-2012
*QRMLOD'RORþHYDQMHHOHPHQWRYYVOHGRYLK'RORþHYDQMHåLYHJDVUHEUDVWHKQLNR
KODGQLKSDUSRUD]WDSOMDQMXY]ODWRWRSNL
Fertilizers - Determination of trace elements - Determination of mercury by vapour
generation (VG) after aqua regia dissolution
Düngemittel und Calcium-/Magnesium-Bodenverbesserungsmittel - Bestimmung von
Elementspuren - Bestimmung von Quecksilber mit Verdampfungstechnik (VG) nach
Königswasseraufschluss
Engrais - Dosage des éléments traces - Détermination du mercure par génération de
vapeur (VG) après digestion à l'eau régale
Ta slovenski standard je istoveten z: CEN/TS 16320:2012
ICS:
65.080 Gnojila Fertilizers
SIST-TS CEN/TS 16320:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST-TS CEN/TS 16320:2012

---------------------- Page: 2 ----------------------

SIST-TS CEN/TS 16320:2012


TECHNICAL SPECIFICATION
CEN/TS 16320

SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION
April 2012
ICS 65.080
English Version
Fertilizers - Determination of trace elements - Determination of
mercury by vapour generation (VG) after aqua regia dissolution
Engrais - Dosage des éléments traces - Détermination du Düngemittel - Bestimmung von Elementspuren -
mercure par génération de vapeur (VG) après digestion à Bestimmung von Quecksilber mit Verdampfungstechnik
l'eau régale (VG) nach Königswasseraufschluss
This Technical Specification (CEN/TS) was approved by CEN on 30 January 2012 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 16320:2012: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST-TS CEN/TS 16320:2012
CEN/TS 16320:2012 (E)
Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Principle .4
5 Sampling and sample preparation .4
6 Reagents .4
7 Apparatus .6
8 Procedure .6
9 Calculation and expression of the results . 10
10 Precision . 12
11 Test report . 14
Annex A (informative) Results of the inter-laboratory test . 15
Bibliography . 16

2

---------------------- Page: 4 ----------------------

SIST-TS CEN/TS 16320:2012
CEN/TS 16320:2012 (E)
Foreword
This document (CEN/TS 16320:2012) 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 [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN/CENELEC Internal Regulations, the national standards organizations 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, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland, Turkey and the United Kingdom.
3

---------------------- Page: 5 ----------------------

SIST-TS CEN/TS 16320:2012
CEN/TS 16320:2012 (E)
1 Scope
This Technical Specification specifies a method for the determination of the content of mercury in fertilizers
after extraction with aqua regia and the detection of mercury by vapour generation (VG) coupled to an atomic
absorption spectrometer or an inductively coupled plasma-atomic emission spectrometer. A limit of
quantification of 0,01 mg/kg is to be expected.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 1482-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample
preparation
EN 12944-1:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 1: General terms
EN 12944-2:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 2: Terms relating
to fertilizers
EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999
apply.
4 Principle
Mercury is extracted from the sample with aqua regia and conventional boiling. The concentration of mercury
in the extract is measured by (cold) vapour generation (VG) coupled to a suitable detector, such as an atomic
absorption spectrometer (AAS) or an inductively coupled plasma-atomic emission spectrometer (ICP-AES).
5 Sampling and sample preparation
Sampling is not part of the methods specified in this Technical Specification. A recommended sampling
method is given in EN 1482-1.
Sample preparation shall be carried out in accordance with EN 1482-2.
6 Reagents
Use only reagents of recognized analytical grade.
Commercially available stock solutions shall be replaced according to the specifications from the supplier or
after one year if prepared in the laboratory from available salts. Standard solutions shall be renewed monthly
as a general rule.
4

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SIST-TS CEN/TS 16320:2012
CEN/TS 16320:2012 (E)
6.1 Water conforming to grade 2 of EN ISO 3696.
6.2 Hydrochloric acid c(HCl) = 12 mol/l; 37 % volume fraction; ρ ≈ 1,18 g/ml.
6.3 Nitric acid c(HNO ) = 16 mol/l; not less than 65 % volume fraction, ρ ≈ 1,42 g/ml.
3
6.4 Mixed solution of 0,8 mol/l nitric acid and 1,8 mol/l hydrochloric acid
Mix 150 ml of hydrochloric acid (6.2) and 50 ml nitric acid (6.3) to 1,0 l of water (6.1).
6.5 Standard stock solution mercury standard stock solution, e.g. ρ = 1 000 mg/l.
Use suitable stock solutions. Single-element stock solutions with adequate specification stating the acid used
and the preparation technique are commercially available. It is recommended to use commercially available
standard stock solutions for mercury.
6.6 Working standard solutions
Depending on the scope, different working standard solutions may be necessary. In general, the stability of
mercury working standard solutions should be checked.
6.6.1 Working standard solution I ρ = 10 mg/l for mercury.
Dilute 1,00 ml of the standard stock solution for mercury (6.5) to 100,0 ml with the mixed acid solution (6.4).
This solution is used to prepare 200 µg/l mercury working standard solution.
6.6.2 Working standard solution II ρ = 200 µg/l for mercury.
Dilute 2,00 ml of the 10 mg/l mercury working standard solution I (6.6.1) to 100,0 ml with the mixed acid
solution (6.4). This solution is used to prepare spiked test solutions and calibration solutions.
6.7 Reducing agents
6.7.1 General
Tin(II) chloride or sodium borohydride may be used as the reducing agent, but it is not advisable to use the
two reagents alternately. Observe 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.
6.7.2 Tin(II) chloride solution ρ(SnCl ·2H O) = 100 g/l.
2 2
Dissolve 50 g of tin(II) chloride in approximately 100 ml of hydrochloric acid (6.2) in a 500 ml volumetric flask
and dilute to the mark. Prepare a fresh solution daily.
6.7.3 Sodium borohydride solution e.g. ρ = 2 g/l.
Dissolve 2 g of sodium hydroxide pellets in water, add 2 g of sodium borohydride and dilute to 1 000 ml with
water (6.1). Prepare a fresh solution daily and, when necessary, filter before use. When the analysis
procedure is of a longer time it is recommended to cool the sodium borohydride solution (i.e. with ice around
the flask) during its use in the vapour generation ICP-AES or AAS measurement.
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 extraction system shall be provided at the point where measurements are
carried out.
5

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SIST-TS CEN/TS 16320:2012
CEN/TS 16320:2012 (E)
7 Apparatus
7.1 Common laboratory glassware
7.2 Analytical balance capable of weighing to an accuracy of 1 mg.
7.3 Inductively coupled plasma-atomic emission spectrometer with axial or radial viewing of the
plasma and with suitable background correction.
The settings of the working conditions (e.g. gas flows, RF or plasma power, sample uptake rate, integration
time, number of replicates) shall be optimised according the manufacturer’s instructions. Radial viewing of the
plasma may be used if it can be shown that the limit of quantification for mercury is below the required legal
limit value.
7.4 Atomic absorption spectrometer equipped with a heated quartz cuvette or a mercury absorption cell,
or optionally with an amalgamation system.
7.5 Vapour generation equipment
7.5.1 Continuous flow or flow-injection cold-vapour system
7.5.2 Element-specific lamp for mercury
7.6 Dilutor
Instrument used for automated volumetric dilutions or other appropriate equipment (e.g. pipettes and
volumetric glassware) to perform dilutions. The precision and accuracy of this type of equipment for volumetric
dilutions shall be established, and controlled and documented regularly.
7.7 Ash-free filter paper i.e. Whatman 589/2 or equivalent quality.
8 Procedure
8.1 General
Calibrations by standard additions with several standards or by matrix matching are very powerful calibration
techniques and can be used to accurately correct for matrix effects from easy-ionisable elements
(multiplicative matrix effects). Additive matrix effects (i.e. spectral interferences) are not corrected for with
standard additions calibration. For matrix matching, additive matrix effects will be corrected for when the
added matrix is the cause of the matrix effect. The main drawback of calibration by standard addition with
several standards is the requirement for a calibration function for each sample type, which is a time
consuming process. For matrix matching a profound knowledge of the sample matrix is needed, which is not
always necessarily available. These two techniques may thus not be practical to use in routine fertilizer
laboratories.
It is therefore suggested that calibrations are to be performed by means of external calibration and correction
of matrix effects by addition of one known spike of a standard solution (spike recovery). The method of
external calibration and correction for spike recovery allows for the analysis of fertilizers with unknown matrix
composition or with a matrix that cannot be synthetically imitated easily. This calibration technique may not be
as precise as calibration by standard additions with several standards but the increased uncertainty is small
compared to the total uncertainty of the method, if the total analyte concentration is in the linear working range
after the spike and the added spike corresponds to at least a doubling of the analyte concentration. Many
matrix errors can be compensated for by this procedure, if they are not additive (e.g. spectral interferences).
Aliquots of the sample solution are analysed by the means of external calibration and then one aliquot is
spiked with known concentrations of the analytes without changing the matrix of the sample solution. The
calculated spike recovery is then used to correct the concentration calculated from the external calibration
6

---------------------- Page: 8 ----------------------

SIST-TS CEN/TS 16320:2012
CEN/TS 16320:2012 (E)
function. The concentration of the spikes shall be in the linear working range of the analytical detection
technique used.
8.2 Preparation of the test solution
8.2.1 General
The following extraction procedure leads, in most cases for mineral fertilizers, to trace element results which
correspond to the total contents of these elements.
Calibration with several standard additions and external calibration after matrix matching may also be used
without any problems.
8.2.2 Preparation
8.2.2.1 Weigh (3 ± 0,003) g of the prepared sample and transfer to a suitable reaction vessel (action 1).
8.2.2.2 Moisten the sample with about 0,5 ml to 1,0 ml of water (6.1) and add, whilst mixing, (21 ± 0,1) ml
of hydrochloric acid (6.2) followed by (7 ± 0,1) ml of nitric acid (6.3), drop by drop if necessary to reduce
foaming. Connect a condenser to the reaction vessel and let the mixture stand at room temperature until any
effervescence almost ceases to allow for slow oxidation of any organic mass in the sample (action 2).
8.2.2.3 Transfer to the heating device and raise the temperature of the reaction mixture slowly to reflux
conditions. Maintain for 2 h, ensuring that the condensation zone is lower than 1/3 of the height of the
condenser, then allow to cool. Rinse the condenser with a further with 10 ml of water (6.1) (action 3).
If the digested sample contains particulates which can clog nebulisers or interfere with the injection of the
sample, the sample should be centrifuged and allowed to settle, or filtered before transferring into a suitable
sized volumetric flask. For example, the solution should be allowed to pass through the filter paper and the
insoluble resi
...

SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 16320:2011
01-november-2011
*QRMLOD'RORþHYDQMHHOHPHQWRYYVOHGRYLK'RORþHYDQMHåLYHJDVUHEUDVWYRUER
SDUHSRUD]WDSOMDQMXY]ODWRWRSNL
Fertilizers - Determination of trace elements - Determination of mercury by vapour
generation (VG) after aqua regia dissolution
Düngemittel und Calcium-/Magnesium-Bodenverbesserungsmittel - Bestimmung von
Elementspuren - Bestimmung von Quecksilber mit Verdampfungstechnik (VG) nach
Königswasseraufschluss
Engrais - Dosage des éléments traces - Détermination du mercure par génération de
vapeur (VG) après digestion à l'eau régale
Ta slovenski standard je istoveten z: FprCEN/TS 16320
ICS:
65.080 Gnojila Fertilizers
kSIST-TS FprCEN/TS 16320:2011 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

kSIST-TS FprCEN/TS 16320:2011

---------------------- Page: 2 ----------------------

kSIST-TS FprCEN/TS 16320:2011


TECHNICAL SPECIFICATION
FINAL DRAFT
FprCEN/TS 16320
SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION

September 2011
ICS 65.080
English Version
Fertilizers - Determination of trace elements - Determination of
mercury by vapour generation (VG) after aqua regia dissolution
Engrais - Dosage des éléments traces - Détermination du Düngemittel - Bestimmung von Elementspuren -
mercure par génération de vapeur (VG) après digestion à Bestimmung von Quecksilber mit Verdampfungstechnik
l'eau régale (VG) nach Königswasseraufschluss


This draft Technical Specification is submitted to CEN members for formal 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland 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

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 16320:2011: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

kSIST-TS FprCEN/TS 16320:2011
FprCEN/TS 16320:2011 (E)
Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Principle .4
5 Sampling and sample preparation .4
6 Reagents .4
7 Apparatus .6
8 Procedure .6
9 Calculation and expression of the results . 10
10 Precision . 12
11 Test report . 14
Annex A (informative) Results of the inter-laboratory test . 15
Bibliography . 16

2

---------------------- Page: 4 ----------------------

kSIST-TS FprCEN/TS 16320:2011
FprCEN/TS 16320:2011 (E)
Foreword
This document (FprCEN/TS 16320:2011) 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 to the Formal Vote.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
3

---------------------- Page: 5 ----------------------

kSIST-TS FprCEN/TS 16320:2011
FprCEN/TS 16320:2011 (E)
1 Scope
This document specifies a method for the determination of the content of mercury in fertilizers after extraction
with aqua regia and detection of mercury by vapour generation (VG) coupled to an atomic absorption
spectrometer or an inductively coupled plasma-atomic emission spectrometer. A limit of quantification of
0,01 mg/kg is to be expected.
2 Normative references
The following referenced documents are indispensable for the application 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 1482-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample
preparation
EN 12944-1:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 1: General terms
EN 12944-2:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 2: Terms relating
to fertilizers
EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696:1987)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999
apply.
4 Principle
Mercury is extracted from the sample with aqua regia and conventional boiling. The concentration of mercury
in the extract is measured by (cold) vapour generation (VG) coupled to a suitable detector such as an atomic
absorption spectrometer (AAS) or an inductively coupled plasma-atomic emission spectrometer (ICP-AES).
5 Sampling and sample preparation
Sampling is not part of the methods specified in this Technical Specification. A recommended sampling
method is given in EN 1482-1.
Sample preparation shall be carried out in accordance with EN 1482-2.
6 Reagents
Use only reagents of recognized analytical grade.
Commercially available stock solutions shall be replaced according to the specifications from supplier or after
one year if prepared in the laboratory from available salts. Standard solutions shall be renewed monthly as a
general rule of thumb.
4

---------------------- Page: 6 ----------------------

kSIST-TS FprCEN/TS 16320:2011
FprCEN/TS 16320:2011 (E)
6.1 Water, conforming to grade 2 of EN ISO 3696.
6.2 Hydrochloric acid, c(HCl) = 12 mol/l; 37 % mass/volume; ρ ≈ 1,18 g/ml.
6.3 Nitric acid, c(HNO ) = 16 mol/l; not less than 65 % mass/volume, ρ ≈ 1,42 g/ml.
3
6.4 Mixed solution of 0,8 mol/l nitric acid and 1,8 mol/l hydrochloric acid.
Mix 150 ml of hydrochloric acid (6.2) and 50 ml nitric acid (6.3) to 1,0 l of water (6.1).
6.5 Standard stock solution, mercury standard stock solution, e.g. ρ = 1 000 mg/l.
Use suitable stock solutions. Single-element stock solutions with adequate specification stating the acid used
and the preparation technique are commercially available. It is recommended to use commercially available
standard stock solutions for mercury.
6.6 Working standard solutions.
Depending on the scope, different working standard solutions may be necessary. In general, the stability of
mercury working standard solutions should be checked.
6.6.1 Working standard solution I, ρ = 10 mg/l for mercury.
Dilute 1,00 ml standard stock solution for mercury (6.5) to 100,0 ml with the mixed acid solution (6.4). This
solution is used to prepare 200 µg/l mercury working standard solution.
6.6.2 Working standard solution II, ρ = 200 µg/l for mercury.
Dilute 2,00 ml 10 mg/l mercury working standard solution I (6.6.1) to 100,0 ml with the mixed acid solution
(6.4). This solution is used to prepare spiked test solutions and calibration solutions.
6.7 Reducing agents.
6.7.1 General.
Tin(II) chloride or sodium borohydride may be used as the reducing agent, but it is not advisable to use the
two reagents alternately. Observe 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.
6.7.2 Tin(II) chloride solution, ρ(SnCl ·2 H O) = 100 g/l.
2 2
Dissolve 50 g of tin(II) chloride, in approximately 100 ml of hydrochloric acid (6.2) in a 500 ml volumetric flask
and dilute to the mark. Prepare a fresh solution every day.
6.7.3 Sodium borohydride solution, e.g. ρ = 2 g/l.
Dissolve 2 g of sodium hydroxide pellets in water, add 2 g of sodium borohydride and dilute to 1 000 ml with
water (6.1). Prepare a fresh solution daily and, when necessary, filter before use. When the analysis
procedure is of longer time it is recommended to cool the sodium borohydride solution, i.e. with ice around the
flask, during its use in the vapour generation ICP-AES or AAS measurement.
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 extraction system shall be provided at the point where measurements are
carried out.
5

---------------------- Page: 7 ----------------------

kSIST-TS FprCEN/TS 16320:2011
FprCEN/TS 16320:2011 (E)
7 Apparatus
7.1 Common laboratory glassware.
7.2 Analytical balance, capable of weighing to an accuracy of 1 mg.
7.3 Inductively coupled plasma-atomic emission spectrometer, with axial or radial viewing of the
plasma and with suitable background correction.
The settings of the working conditions (e.g. gas flows, RF or plasma power, sample uptake rate, integration
time, number of replicates) shall be optimised according the manufacturer’s instructions. Radial viewing of the
plasma may be used if it can be shown that the limit of quantification for mercury is below the required legal
limit value.
7.4 Atomic absorption spectrometer, equipped with a heated quartz cuvette or a mercury absorption cell,
or optionally with an amalgamation system.
7.5 Vapour generation equipment.
7.5.1 Continuous flow or flow-injection cold-vapour system.
7.5.2 Element-specific lamp for mercury.
7.6 Dilutor.
Instrument used for automated volumetric dilutions or other appropriate equipment (e.g. pipettes and
volumetric glassware) to perform dilutions. The precision and accuracy of this type of equipment for volumetric
dilutions shall be established, and controlled and documented regularly.
7.7 Ash-free filter paper, i.e. Whatman 589/2 or equivalent quality.
8 Procedure
8.1 General
Calibrations by standard additions with several standards or by matrix matching are very powerful calibration
techniques and can be used to accurately correct for matrix effects from easy-ionisable elements
(multiplicative matrix effects). Additive matrix effects (i.e. spectral interferences) are not corrected for with
standard additions calibration. For matrix matching, additive matrix effects will be corrected for when the
added matrix is the cause of the matrix effect. The main drawback of calibration by standard addition with
several standards is the requirement for a calibration function for each sample type, which is a time
consuming process. For matrix matching a profound knowledge of the sample matrix is needed, which is not
necessarily available. These two techniques may thus not be practical to use in routine fertilizer laboratories.
It is therefore suggested that calibration are to be performed by means of external calibration and correction of
matrix effects by addition of one known spike of a standard solution (spike recovery). The method of external
calibration and correction for spike recovery allows for the analysis of fertilizers with unknown matrix
composition or with a matrix that cannot be synthetically imitated easily. This calibration technique may not be
as precise as calibration by standard additions with several standards but the increased uncertainty is small
compared to the total uncertainty of the method, if the total analyte concentration is in the linear working range
after the spike and the added spike corresponds to at least a doubling of the analyte concentration. Many
matrix errors can be compensated for by this procedure, if they are not additive (e.g. spectral interferences).
Aliquots of the sample solution are analysed by the mean of external calibration and then one aliquot is spiked
with known concentrations of the analytes without changing the matrix of the sample solution. The calculated
spike recovery is then used to correct the concentration calculated from the external calibration function. The
concentration of the spikes shall be in the linear working range of the analytical detection technique used.
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kSIST-TS FprCEN/TS 16320:2011
FprCEN/TS 16320:2011 (E)
8.2 Preparation of the test solution
8.2.1 General
The following extraction procedure leads, in most cases, for mineral fertilizers, to trace element results which
correspond to the total contents of these elements.
Calibration with several standard additions and external calibration after matrix matching may also be used
with no problems.
8.2.2 Preparation
8.2.2.1 Weigh 3 g ± 0,003 g of the prepared sample and transfer to a suitable reaction vessel (action 1).
8.2.2.2 Moisten the sample with about 0,5 ml to 1,0 ml of water (6.1) and add, with mixing, 21 ml ± 0,1 ml
of hydrochloric acid (6.2) followed by 7 ml ± 0,1 ml of nitric acid (6.3) drop wise if necessary to reduce
foaming. Connect a condenser to the reaction vessel and let the mixture stand at room temperature until any
effervescence almost ceases to allow for slow oxidation of any organic mass in the sample (action 2).
8.2.2.3 Transfer to the heating device and raise the temperature of the reaction mixture slowly to reflux
conditions and maintain for 2 h ensuring that the condensation zone is lower than 1/3 of the height of the
condenser, then allow to cool. Rinse the condenser with further with 10 ml of water (6.1) (action 3).
If the digested sample contains particulates which can clog nebulisers or interfere with the injection of the
sample, the sample should be centrifuged, allowed to settle, or filtered before transferring into a suitable sized
volumetric flask. For example, the solution should be allowed to pass through the filter paper and then the
insoluble residue washed onto the filter paper with a minimum of water (6.1). The method used has to be
reported in the test report. Filter paper may cause contaminations (e.g. lead) and it may be necessary to use
ash-free filter paper (7.7).
8.2.2.4 Transfer the digested sample into a 150 ml volumetric flask and dilute to the mark with water
(6.1). This yields an acid concentration approximately equal to the mixed acid solution (6.4). This test solution
corresponds to a 50 times dilution of the solid sample (action 4).
8.2.2.5 Test solutions are diluted w
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