SIST-TS CEN/TS 16317:2012
(Main)Fertilizers - Determination of trace elements - Determination of arsenic by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution
Fertilizers - Determination of trace elements - Determination of arsenic by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution
This document specifies a method for the determination of the content of arsenic in fertilizers using inductively coupled plasma atomic emission spectrometry (ICP-AES) after aqua regia dissolution. Limits of quantification are dependant on the sample matrix as well as on the instrument, but can roughly be expected to be 1,5 mg/kg for As.
Düngemittel und Calcium-/Magnesium-Bodenverbesserungsmittel - Bestimmung von Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss
Diese Technische Spezifikation legt ein Verfahren zur Bestimmung von Arsen in Düngemitteln mittels Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss fest. Die Bestimmungsgrenzen sind sowohl von der Probenmatrix als auch vom eingesetzten Gerät abhängig, werden jedoch für Arsen bei etwa 1,5 mg/kg erwartet.
Engrais - Dosage des éléments traces - Détermination de l'arsenic par spectrométrie d'émission atomique avec plasma induit par haute fréquence (ICP-AES) après digestion à l'eau régale
Cette spécification technique spécifie une méthode permettant de déterminer la teneur en arsenic dans les engrais par spectrométrie d’émission atomique avec plasma à couplage inductif (ICP-AES) après dissolution dans l’eau régale. Les limites de quantification dépendent de la matrice de l’échantillon ainsi que de l’instrument, mais devraient se situer autour de 1,5 mg/kg pour l’As.
Gnojila - Določevanje elementov v sledovih - Določevanje arzena z atomsko emisijsko spektrometrijo z induktivno sklopljeno plazmo (ICP/AES) po raztapljanju v zlatotopki
Ta dokument določa metodo za določevanje vsebnosti arzena v gnojilih z atomsko emisijsko spektrometrijo z induktivno sklopljeno plazmo (ICP-AES) po raztapljanju v zlatotopki. Meje kvantifikacije so odvisne od matrice vzorca in instrumenta, vendar so za As običajno približno 1,5 mg/kg.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 16317:2012
01-junij-2012
*QRMLOD'RORþHYDQMHHOHPHQWRYYVOHGRYLK'RORþHYDQMHDU]HQD]DWRPVNR
HPLVLMVNRVSHNWURPHWULMR]LQGXNWLYQRVNORSOMHQRSOD]PR ,&3$(6 SRUD]WDSOMDQMX
Y]ODWRWRSNL
Fertilizers - Determination of trace elements - Determination of arsenic by inductively
coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution
Düngemittel und Calcium-/Magnesium-Bodenverbesserungsmittel - Bestimmung von
Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv
gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss
Engrais - Dosage des éléments traces - Détermination de l'arsenic par spectrométrie
d'émission atomique avec plasma induit par haute fréquence (ICP-AES) après digestion
à l'eau régale
Ta slovenski standard je istoveten z: CEN/TS 16317:2012
ICS:
65.080 Gnojila Fertilizers
SIST-TS CEN/TS 16317:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST-TS CEN/TS 16317:2012
---------------------- Page: 2 ----------------------
SIST-TS CEN/TS 16317:2012
TECHNICAL SPECIFICATION
CEN/TS 16317
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
April 2012
ICS 65.080
English Version
Fertilizers - Determination of trace elements - Determination of
arsenic by inductively coupled plasma-atomic emission
spectrometry (ICP-AES) after aqua regia dissolution
Engrais - Dosage des éléments trace - Détermination de Düngemittel - Bestimmung von Elementspuren -
l'arsenic par spectrométrie d'émission atomique avec Bestimmung von Arsen mit Atomemissionsspektrometrie
plasma induit par haute fréquence (ICP-AES) après mit induktiv gekoppeltem Plasma (ICP-AES) nach
digestion à l'eau régale 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 16317:2012: E
worldwide for CEN national Members.
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SIST-TS CEN/TS 16317:2012
CEN/TS 16317:2012 (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 .5
8 Procedure .6
9 Calculation and expression of the results .9
10 Precision . 11
11 Test report . 12
Annex A (informative) Results of the inter-laboratory test . 13
A.1 Inter-laboratory tests . 13
A.2 Statistical results for the determination of arsenic by ICP-AES . 13
Bibliography . 14
2
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SIST-TS CEN/TS 16317:2012
CEN/TS 16317:2012 (E)
Foreword
This document (CEN/TS 16317:2012) 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
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SIST-TS CEN/TS 16317:2012
CEN/TS 16317:2012 (E)
1 Scope
This Technical Specification specifies a method for the determination of the content of arsenic in fertilizers
using inductively coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution. Limits
of quantification are dependent on the sample matrix as well as on the instrument, but can roughly be
expected to be 1,5 mg/kg for As.
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
Arsenic is extracted from the sample with aqua regia and conventional boiling. The concentration in the extract
is measured by inductively coupled plasma–atomic emission spectrometry (ICP-AES) with axial or radial
viewing.
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 16317:2012
CEN/TS 16317:2012 (E)
6.1 Water according to EN ISO 3696, grade 2.
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 arsenic standard stock solution, e. g. ρ = 1 000 mg/l in arsenic.
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 a commercially available
standard stock solution for arsenic.
6.6 Working standard solutions
Depending on the scope, different working standard solutions may be necessary.
6.6.1 Working standard solution I ρ = 100 mg/l for arsenic.
Dilute 10,0 ml of the stock solution of arsenic (6.5) to 100,0 ml with the mixed acid solution (6.4) in the same
100 ml flask. This solution is used to prepare spiked test solutions and standard and calibration solutions.
6.6.2 Working standard solution II ρ = 10 mg/l for arsenic.
Dilute 10,0 ml of the working standard solution I (6.6.1) to 100,0 ml with the mixed acid solution (6.4) in a
100 ml flask. This solution is used to prepare spiked test solutions and calibration solutions.
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 arsenic is below the required legal
limit values.
The use of axial orientation of the viewing optics requires good control of the matrix effects coming from
"easily ionisable elements" (i.e. the influence of easily ionisable elements in varying concentrations on the
signal intensities of the analytes). For alkali-elements, this can be achieved by adding caesium-chloride
solution (CsCl). In general, matrix matching of calibration solutions or calibration by standard additions with
several calibration standards will correct accurately for these matrix effects. Spike recovery of one known
standard combined with external calibration can, if used properly, also correct sufficiently for matrix effects
(see 8.1). Correction by internal standardisation is also a good option, but the accuracy of the measurements
after internal standard correction should be validated properly prior to use on unknown fertilizer samples.
5
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SIST-TS CEN/TS 16317:2012
CEN/TS 16317:2012 (E)
7.4 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.
7.5 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.
Correction by internal standardisation is also a good option, but the accuracy of the measurements after
internal standard correction should be validated properly prior to use on unknown fertilizer samples.
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 fertilisers 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
function. The concentration of the spikes shall be in the linear working range of the ICP-AES.
8.2 Preparation of the test solution
8.2.1 General
The following extraction procedure leads, in most cases for mineral fertilisers, to trace element results which
correspond to the total contents of these elements.
Calibration with several standard additions and external calibration after matrix matching or by correction for
matrix effects with internal standardization may also be used.
8.2.2 Preparation
8.2.2.1 Weigh (3 ± 0,003) g of the prepared sample and transfer to a sui
...
SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 16317:2011
01-november-2011
*QRMLOD'RORþHYDQMHHOHPHQWRYYVOHGRYLK'RORþHYDQMHDU]HQD]DWRPVNR
HPLVLMVNRVSHNWURPHWULMR]LQGXNWLYQRVNORSOMHQRSOD]PR ,&3$(6 SRUD]WDSOMDQMX
Y]ODWRWRSNL
Fertilizers - Determination of trace elements - Determination of arsenic by inductively
coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution
Düngemittel und Calcium-/Magnesium-Bodenverbesserungsmittel - Bestimmung von
Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv
gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss
Ta slovenski standard je istoveten z: FprCEN/TS 16317
ICS:
65.080 Gnojila Fertilizers
kSIST-TS FprCEN/TS 16317:2011 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
kSIST-TS FprCEN/TS 16317:2011
---------------------- Page: 2 ----------------------
kSIST-TS FprCEN/TS 16317:2011
TECHNICAL SPECIFICATION
FINAL DRAFT
FprCEN/TS 16317
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
September 2011
ICS 65.080
English Version
Fertilizers - Determination of trace elements - Determination of
arsenic by inductively coupled plasma-atomic emission
spectrometry (ICP-AES) after aqua regia dissolution
Düngemittel - Bestimmung von Elementspuren -
Bestimmung von Arsen mit Atomemissionsspektrometrie
mit induktiv gekoppeltem Plasma (ICP-AES) 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 16317:2011: E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
kSIST-TS FprCEN/TS 16317:2011
FprCEN/TS 16317:2011 (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 .5
8 Procedure .6
9 Calculation and expression of the results .9
10 Precision . 11
11 Test report . 12
Annex A (informative) Results of the inter-laboratory test . 13
A.1 Inter-laboratory tests . 13
A.2 Statistical results for the determination of arsenic by ICP-AES . 13
Bibliography . 14
2
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kSIST-TS FprCEN/TS 16317:2011
FprCEN/TS 16317:2011 (E)
Foreword
This document (FprCEN/TS 16317:2011) 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
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kSIST-TS FprCEN/TS 16317:2011
FprCEN/TS 16317:2011 (E)
1 Scope
This document specifies a method for the determination of the content of arsenic in fertilizers using inductively
coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution. Limits of quantification
are dependant on the sample matrix as well as on the instrument, but can roughly be expected to be
1,5 mg/kg for As.
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
Arsenic is extracted from the sample with aqua regia and conventional boiling. The concentration in the extract
is measured by inductively coupled plasma–atomic emission spectrometry (ICP-AES) with axial or radial
viewing.
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 16317:2011
FprCEN/TS 16317:2011 (E)
6.1 Water, conforming to grade 2 according to 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, arsenic standard stock solution, e.g. ρ = 1 000 mg/l in arsenic.
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 a commercially available
standard stock solution for arsenic.
6.6 Working standard solutions.
Depending on the scope, different working standard solutions may be necessary.
6.6.1 Working standard solution I, ρ = 100 mg/l for arsenic.
Dilute 10,0 ml of the stock solution of arsenic (6.5) to 100,0 ml with the mixed acid solution (6.4) in the same
100 ml flask. This solution is used to prepare spiked test solutions and standard and calibration solutions.
6.6.2 Working standard solution II, ρ = 10 mg/l for arsenic.
Dilute 10,0 ml of the working standard solution I (6.6.1) to 100,0 ml with the mixed acid solution (6.4) in a
100 ml flask. This solution is used to prepare spiked test solutions and calibration solutions.
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 arsenic is below the required legal
limit values.
The use of axial orientation of the viewing optics requires good control on the matrix effects coming from
„easily ionisable elements“ (i.e. the influence of easily ionisable elements in varying concentrations on the
signal intensities of the analytes). For alkali-elements, this can be done by adding caesium-chloride solution
(CsCl). In general, matrix matching of calibration solutions or calibration by standard additions with several
calibration standards will correct accurately for these matrix effects. Spike recovery of one known standard
combined with external calibration can, if used properly, also correct sufficiently for matrix effects (see 8.1).
Correction by internal standardisation is also a good option, but the accuracy of the measurements after
internal standard correction should be validated properly prior to use on unknown fertilizer samples.
5
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kSIST-TS FprCEN/TS 16317:2011
FprCEN/TS 16317:2011 (E)
7.4 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.
7.5 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.
Correction by internal standardisation is also a good option, but the accuracy of the measurements after
internal standard correction should be validated properly prior to use on unknown fertilizer samples.
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 fertilisers 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 ICP-AES.
8.2 Preparation of the test solution
8.2.1 General
The following extraction procedure leads, in most cases, for mineral fertilisers, to trace element results which
correspond to the total contents of these elements.
Calibration with several standard additions and external calibration after matrix matching or by correction for
matrix effects with internal standardization may also be used.
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).
6
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kSIST-TS FprCEN/TS 16317:2011
FprCEN/TS 16317:2011 (E)
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
...
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