SIST EN 16317:2013
(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 European Standard 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.
Düngemittel - Bestimmung von Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss
Diese Europäische Norm 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 norme européenne 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 evropski standard 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.
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Düngemittel - Bestimmung von Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach KönigswasseraufschlussEngrais - 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 régaleFertilizers - Determination of trace elements - Determination of arsenic by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution65.080GnojilaFertilizersICS:Ta slovenski standard je istoveten z:EN 16317:2013SIST EN 16317:2013en,fr,de01-december-2013SIST EN 16317:2013SLOVENSKI
STANDARDSIST-TS CEN/TS 16317:20121DGRPHãþD
SIST EN 16317:2013
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16317
October 2013 ICS 65.080 Supersedes CEN/TS 16317:2012English 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 traces - Détermination de l'arsenic par spectrométrie d'émission atomique avec plasma induit par haute fréquence (ICP-AES) après digestion à
l'eau régale
Düngemittel - Bestimmung von Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss This European Standard was approved by CEN on 29 August 2013.
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, Former Yugoslav Republic of Macedonia, 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 © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16317:2013: ESIST EN 16317:2013
EN 16317:2013 (E) 2 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 8.1 General . 6 8.2 Preparation of the test solution . 6 8.2.1 General . 6 8.2.2 Preparation . 6 8.3 Preparation of the test solution for the correction of matrix effects by spike recovery . 7 8.4 Preparation of the blank test solution . 7 8.5 Preparation of the calibration solutions for the analysis of arsenic . 8 8.6 Determination of arsenic by ICP-AES . 8 8.6.1 General . 8 8.6.2 Determination by ICP-AES . 8 9 Calculation and expression of the results . 9 9.1 External calibration . 9 9.2 Correction for spike recovery . 9 9.3 Standard addition method . 10 9.4 Calculation of the element content in the sample . 11 10 Precision . 11 10.1 Inter laboratory tests . 11 10.2 Repeatability . 11 10.3 Reproducibility . 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
SIST EN 16317:2013
EN 16317:2013 (E) 3 Foreword This document (EN 16317:2013) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials”, 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 April 2014, and conflicting national standards shall be withdrawn at the latest by April 2014. 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 supersedes CEN/TS 16317:2012. The following changes have been made to the former edition: a) the CEN Technical Specification has been adopted as a European Standard; b) the document has been editorially revised. 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 organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, 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.
SIST EN 16317:2013
EN 16317:2013 (E) 4 1 Scope This European Standard 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 European Standard. 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 recognised 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.
6.1 Water, according to EN ISO 3696, grade 2. 6.2 Hydrochloric acid, c(HCl) = 12 mol/l; 37 % volume fraction;
≈ 1,18 g/ml. 6.3 Nitric acid, c(HNO3) = 16 mol/l; not less than 65 % volume fraction, ρ ≈ 1,42 g/ml. SIST EN 16317:2013
EN 16317:2013 (E) 5 6.4 Mixed acid 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.
= 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,
= 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,
= 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 to 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. 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.
SIST EN 16317:2013
EN 16317:2013 (E) 6 7.5 Ash-free filter paper, i.e. Whatman 589/2®1) 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 fertilizers with unknown matrix composition or with a matrix that cannot be easily imitated synthetically. This calibration technique may not be as precise as calibration by standard additions with several stand
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Düngemittel - Bestimmung von Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach KönigswasseraufschlussEngrais - 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 régaleFertilizers - Determination of trace elements - Determination of arsenic by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after aqua regia dissolution65.080GnojilaFertilizersICS:Ta slovenski standard je istoveten z:FprEN 16317kSIST FprEN 16317:2013en,fr,de01-maj-2013kSIST FprEN 16317:2013SLOVENSKI
STANDARD
kSIST FprEN 16317:2013
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN 16317
February 2013 ICS 65.080 Will supersede CEN/TS 16317:2012English 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 traces - Détermination de l'arsenic par spectrométrie d'émission atomique avec plasma induit par haute fréquence (ICP-AES) après digestion à
l'eau régale
Düngemittel - Bestimmung von Elementspuren - Bestimmung von Arsen mit Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP-AES) nach Königswasseraufschluss This draft European Standard is submitted to CEN members for unique acceptance procedure. It has been drawn up by the Technical Committee CEN/TC 260.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, Former Yugoslav Republic of Macedonia, 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.
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 European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. FprEN 16317:2013: EkSIST FprEN 16317:2013
FprEN 16317:2013 (E) 2 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 8.1 General .6 8.2 Preparation of the test solution .6 8.2.1 General .6 8.2.2 Preparation .6 8.3 Preparation of the test solution for the correction of matrix effects by spike recovery .7 8.4 Preparation of the blank test solution .7 8.5 Preparation of the calibration solutions for the analysis of arsenic .7 8.6 Determination of arsenic by ICP-AES .8 8.6.1 General .8 8.6.2 Determination by ICP-AES .8 9 Calculation and expression of the results .9 9.1 External calibration.9 9.2 Correction for spike recovery .9 9.3 Standard addition method . 10 9.4 Calculation of the element content in the sample . 11 10 Precision . 11 10.1 Inter laboratory tests . 11 10.2 Repeatability . 11 10.3 Reproducibility . 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
kSIST FprEN 16317:2013
FprEN 16317:2013 (E) 3 Foreword This document (FprEN 16317:2013) 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 Unique Acceptance Procedure. This document will supersede CEN/TS 16317:2012. The following changes have been made to the former edition: a) The CEN Technical Specification has been adopted as a European Standard; b) The document has been editorially revised. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. kSIST FprEN 16317:2013
FprEN 16317:2013 (E) 4 1 Scope This European Standard 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 European Standard. 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.
6.1 Water, according to EN ISO 3696, grade 2. 6.2 Hydrochloric acid, c(HCl) = 12 mol/l; 37 % volume fraction;
≈ 1,18 g/ml. 6.3 Nitric acid, c(HNO3) = 16 mol/l; not less than 65 % volume fraction, ρ ≈ 1,42 g/ml. kSIST FprEN 16317:2013
FprEN 16317:2013 (E) 5 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.
= 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,
= 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,
= 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 to 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. 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. kSIST FprEN 16317:2013
FprEN 16317:2013 (E) 6 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 standar
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