Animal feeding stuffs: Methods of sampling and analysis - Determination of calcium, sodium, phosphorus, magnesium, potassium, sulphur, iron, zinc, copper, manganese and cobalt after pressure digestion by ICP-AES

This European Standard specifies a method for the determination of the elements calcium, sodium, phosphorus, magnesium, potassium, sulphur, iron, zinc, copper, manganese and cobalt in animal feeding stuffs by inductively coupled plasma atomic emission spectrometry (ICP-AES) after pressure digestion.
The method was fully statistically tested and evaluated for the elements calcium, sodium, phosphorus, magnesium, potassium, sulphur, iron, zinc, copper, manganese and cobalt within the following 11 animal feeds: 2 complete feeds (pig feed, sheep feed), 3 complementary feeds (3 mineral feeds), 1 mineral premixture, 3 feed materials (MgO, phosphate, CaCO3) and 2 feed additives (CuSO4, bentonite).
For potassium and sulphur the HORRAT values were mostly higher than 2. Therefore, for these elements the method is more applicable as a screening method and not for confirmatory purposes.
Other elements like molybdenum, lead, cadmium, arsenic were not fully statistically tested and evaluated within 11 animal feeding stuff samples because these elements did not occur in concentrations higher than the limit of quantification in most of these samples. A single laboratory validation is therefore necessary for the use of this multi element method for these elements.
For the determination of extractable lead in minerals and feeds, containing phyllosilicates (e.g. kaolinite clay) wet digestion with nitric acid should be used.
The method limit of quantification for each element is dependent on the sample matrix as well as on the instrument. The method is not applicable for determination of low concentrations of elements. A limit of quantification of 1 mg/kg should normally be obtained.
NOTE 1   This method can also be used for the determination in products with high content (> 5 %) of the element to be measured, but for this purpose the accuracy of the method has to be checked individually.
NOTE 2   Results of this European Standard EN 15621 may be higher than of EN 15510 because EN 15621 is using pressure digestion mode.

Futtermittel - Probenahme- und Untersuchungsverfahren - Bestimmung von Calcium, Natrium, Phosphor, Magnesium, Kalium, Schwefel, Eisen, Zink, Kupfer, Mangan und Kobalt nach Druckaufschluss mittels ICP-AES

Diese Europäische Norm legt ein Verfahren zur Bestimmung der Elemente Calcium, Natrium, Phosphor, Magnesium, Kalium, Schwefel, Eisen, Zink, Kupfer, Mangan und Kobalt in Futtermitteln mittels Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICPAES) nach Druckaufschluss fest.
Das Verfahren wurde für die Elemente Calcium, Natrium, Phosphor, Magnesium, Kalium, Schwefel, Eisen, Zink, Kupfer, Mangan und Kobalt in den folgenden 11 Tierfuttermitteln vollständig statistisch geprüft und bewertet: 2 Alleinfuttermittel (Schweine-, Schaffutter), 3 Ergänzungsfuttermittel (3 Mineralstoff-mischungen), 1 Mineralstoffvormischung, 3 Einzelfuttermittel (MgO, Phosphat, CaCO3) und 2 Futtermittel-Zusatzstoffe (CuSO4, Bentonit).
Bei Kalium und Schwefel waren die HorRat-Werte meistens höher als 2. Deshalb ist das Verfahren für diese Elemente eher als Screening-Verfahren und nicht für Bestätigungszwecke geeignet.
Die bei anderen Elementen, wie Molybdän, Blei, Cadmium und Arsen, erzielten Ergebnisse wurden im Rahmen von 11 Futtermittelproben nicht vollständig statistisch geprüft und bewertet, da diese Elemente nicht in Konzentrationen vorkamen, die in den meisten dieser Proben höher als die Bestimmungsgrenze waren. Deshalb ist bei Anwendung dieses Mehrelementverfahrens eine einzelne laborspezifische Validierung notwendig.
Zur Bestimmung von extrahierbarem Blei in Mineralstoffen und Futtermitteln, die Schichtsilikate enthalten (z. B. kaolinitischer Ton), sollte Nassaufschluss mit Salpetersäure verwendet werden.
Die Bestimmungsgrenze des Verfahrens ist bei jedem Element sowohl von der Probenmatrix als auch von dem Gerät abhängig. Das Verfahren ist nicht für die Bestimmung von geringen Elementkonzentrationen anwendbar. Eine Bestimmungsgrenze von 1 mg/kg sollte normalerweise erreicht werden.
ANMERKUNG 1   Dieses Verfahren kann ebenfalls zur Bestimmung in Produkten mit hohem Gehalt des zu messenden Elements (> 5 %) angewendet werden, jedoch muss die Fehlergrenze des Verfahrens im Einzelfall geprüft werden.
ANMERKUNG 2   Die Ergebnisse nach dieser Europäischen Norm EN 15621 können höher sein als die nach EN 15510, da EN 15621 die Druckaufschlussmethode verwendet.

Aliments pour animaux : Méthodes d’échantillonnage et d’analyse - Dosage du calcium, du sodium, du phosphore, du magnésium, du potassium, du soufre, du fer, du zinc, du cuivre, du manganèse et du cobalt après digestion sous pression par ICP-AES

La présente Norme européenne spécifie une méthode de détermination de la teneur en calcium, sodium, phosphore, magnésium, potassium, soufre, fer, zinc, cuivre, manganèse et cobalt présents dans les aliments pour animaux par spectrométrie d’émission atomique à plasma à couplage inductif (ICP AES) après digestion sous pression.
La méthode a été soumise à un essai statistique complet et à une évaluation pour doser les éléments suivants: calcium, sodium, phosphore, magnésium, potassium, soufre, fer, zinc, cuivre, manganèse et cobalt sur 11 aliments pour animaux : 2 aliments complets (un aliment pour porc et un pour ovin), 3 compléments alimentaires pour animaux (3 minéraux pour l’alimentation animale), 1 prémélange minéral, 3 matières minérales destinées aux aliments des animaux (MgO, phosphate, CaCO3) et 2 additifs pour l’alimentation animale (CuSO4, bentonite).
Dans le cas du potassium et du soufre, les valeurs HORRAT sont pour la plupart supérieures à 2. Par conséquent, pour ces éléments, la méthode est applicable en tant que méthode d’évaluation et non pas à des fins de confirmation.
D’autres éléments tels que le molybdène, le plomb, le cadmium et l’arsenic n’ont pas été soumis à un essai statistique complet ni à une évaluation sur les 11 échantillons d’aliments pour animaux, car leur concentration n’était pas supérieure à la limite de quantification dans la plupart des échantillons. Une validation interne par chaque laboratoire est par conséquent nécessaire pour utiliser cette méthode avec ces éléments.
Pour la détermination de la teneur en plomb extractible dans les minéraux et les aliments pour animaux contenant des phyllosilicates (argiles à kaolinite, par exemple), il convient d’utiliser une digestion humide à l’acide nitrique.
La limite de quantification de la méthode pour chacun des éléments est fonction de la matrice de l’échantillon et de l’instrument. Cette méthode ne permet pas la détermination des éléments en faibles concentrations. Il convient de parvenir à une limite de quantification de 1 mg/kg, dans des conditions d’essai normales.
NOTE 1   Cette méthode peut également servir au dosage dans des produits à teneur élevée en éléments (> 5 %), mais à cette fin, l’exactitude de la méthode doit être vérifiée sur une base individuelle.
NOTE 2   Les résultats de la présente Norme européenne EN 15621 peuvent être supérieurs à ceux de l’EN 15510, car l’EN 15621 utilise le mode de digestion sous pression.

Krma: metode vzorčenja in analize - Določevanje kalcija, natrija, fosforja, magnezija, kalija, žvepla, železa, cinka, bakra, mangana in kobalta po razklopu pod tlakom z ICP-AES

Ta evropski standard določa metodo za določevanje kalcija, natrija, fosforja, magnezija, kalija, žvepla, železa, cinka, bakra, mangana in kobalta v krmi z atomsko emisijsko spektrometrijo z induktivno sklopljeno plazmo (ICP-AES) po razklopu pod tlakom.
Metoda je bila v celoti statistično preizkušena in ocenjena za kalcij, natrij, fosfor, magnezij, kalij, žveplo, železo, cink, baker, mangan in kobalt v naslednjih enajstih krmah: dveh celovitih krmah (krmi za prašiče, krmi za ovce), treh dopolnilnih krmah (treh mineralnih krmah), enem mineralnem premiksu, treh sestavinah krme (MgO, fosfatu, CaCO3) in dveh dodatkih za krmo (CuSO4, bentonitu).
Vrednosti HORRAT so bile pri kaliju in žveplu večinoma višje od 2. Zato je pri teh dveh elementih ta metoda bolj ustrezna kot presejalna metoda in ne kot metoda za potrditev.
Drugi elementi, kot so molibden, svinec, kadmij in arzen, niso bili v celoti statistično testirani in ovrednoteni na 11 vzorcih krme, ker se v večini teh vzorcev niso pojavljali v koncentracijah, višjih od meje kvantifikacije. Zato je za uporabo te večelementarne metode pri teh elementih potrebna ena sama laboratorijska validacija.
Za določevanje izločljivega svinca v mineralih in krmah, ki vsebujejo filosilikate (npr. kaolinitna glina), je treba uporabiti postopek mokrega razklopa z dušikovo kislino.
Meja kvantifikacije vseh elementov je pri tej metodi odvisna od matrice vzorca in instrumenta. Metoda se ne uporablja za določevanje nizkih koncentracij elementov. Običajno je treba doseči mejo kvantifikacije 1 mg/kg.
OPOMBA 1   Ta metoda se lahko uporablja tudi za določevanje koncentracije v izdelkih z visoko vsebnostjo (> 5 %) elementa, ki se ga meri, vendar je treba natančnost metode za ta namen preveriti posebej.
OPOMBA 2   Rezultati, pridobljeni skladno s tem evropskim standardom EN 15621, so lahko višji kot rezultati, pridobljeni skladno s standardom EN 15510, ker standard EN 15621 uporablja način razklopa pod tlakom.

General Information

Status
Published
Publication Date
08-Aug-2017
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
09-Aug-2017
Completion Date
09-Aug-2017

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SLOVENSKI STANDARD
SIST EN 15621:2017
01-oktober-2017
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Animal feeding stuffs: Methods of sampling and analysis - Determination of calcium,

sodium, phosphorus, magnesium, potassium, sulphur, iron, zinc, copper, manganese
and cobalt after pressure digestion by ICP-AES
Futtermittel - Probenahme- und Untersuchungsverfahren - Bestimmung von Calcium,
Natrium, Phosphor, Magnesium, Kalium, Schwefel, Eisen, Zink, Kupfer, Mangan und
Kobalt nach Druckaufschluss mittels ICP-AES

Aliments pour animaux : Méthodes d’échantillonnage et d’analyse - Dosage du calcium,

du sodium, du phosphore, du magnésium, du potassium, du soufre, du fer, du zinc, du

cuivre, du manganèse et du cobalt après digestion sous pression par ICP-AES
Ta slovenski standard je istoveten z: EN 15621:2017
ICS:
65.120 Krmila Animal feeding stuffs
SIST EN 15621:2017 en,fr,de

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

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SIST EN 15621:2017
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SIST EN 15621:2017
EN 15621
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2017
EUROPÄISCHE NORM
ICS 65.120 Supersedes EN 15621:2012
English Version
Animal feeding stuffs: Methods of sampling and analysis -
Determination of calcium, sodium, phosphorus,
magnesium, potassium, sulphur, iron, zinc, copper,
manganese and cobalt after pressure digestion by ICP-AES

Aliments pour animaux : Méthodes d'échantillonnage Futtermittel - Probenahme- und

et d'analyse - Dosage du calcium, du sodium, du Untersuchungsverfahren - Bestimmung von Calcium,

phosphore, du magnésium, du potassium, du soufre, du Natrium, Phosphor, Magnesium, Kalium, Schwefel,

fer, du zinc, du cuivre, du manganèse et du cobalt après Eisen, Zink, Kupfer, Mangan und Kobalt nach

digestion sous pression par ICP-AES Druckaufschluss mittels ICP-AES
This European Standard was approved by CEN on 6 February 2017.

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, 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: Avenue Marnix 17, B-1000 Brussels

© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 15621:2017 E

worldwide for CEN national Members.
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SIST EN 15621:2017
EN 15621:2017 (E)
Contents Page

European foreword ....................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 5

4 Principle ............................................................................................................................................................. 5

5 Reagents ............................................................................................................................................................. 6

6 Apparatus ........................................................................................................................................................... 6

7 Sampling ............................................................................................................................................................. 7

8 Preparation of the test sample ................................................................................................................... 7

8.1 General ................................................................................................................................................................ 7

8.2 Animal feeding stuffs which can be ground as such ........................................................................... 8

8.3 Liquid animal feeding stuffs ........................................................................................................................ 8

9 Procedure........................................................................................................................................................... 8

9.1 Pressure digestion – Preparation of the blank test solution and the test solution ................. 8

9.2 Extractable lead in minerals and feeds containing phyllosilicates (e.g. kaolinite clay)

– extraction with diluted nitric acid ......................................................................................................... 9

9.3 Calibration ......................................................................................................................................................... 9

9.4 Determination .................................................................................................................................................. 9

Table 1 — Selected emission wavelengths and interferences for determination with ICP-AES ... 10

10 Calculation and expression of the results ........................................................................................... 11

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

10.2 External calibration .................................................................................................................................... 11

10.3 Standard addition method with only one addition .......................................................................... 11

10.4 Standard addition method with several additions .......................................................................... 12

10.5 Calculation of the element content in the sample ............................................................................ 12

11 Precision .......................................................................................................................................................... 13

11.1 Inter-laboratory test ................................................................................................................................... 13

11.2 Repeatability .................................................................................................................................................. 13

11.3 Reproducibility ............................................................................................................................................. 13

Table 2 — Precision data – Ca, K, Mg, Na, P, S ................................................................................................... 14

Table 3 — Precision data – Co, Cu, Fe, Mn, Mo, Zn, Cd, As, Pb ..................................................................... 17

12 Test report ...................................................................................................................................................... 21

Annex A (informative) Results of the inter-laboratory test ....................................................................... 22

Table A.1 — Statistical results of an inter-laboratory test – Calcium (Ca) ............................................ 23

Table A.2 — Statistical results of an inter-laboratory test – Potassium (K) ......................................... 24

Table A.3 — Statistical results of an inter-laboratory test – Magnesium (Mg) .................................... 25

Table A.4 — Statistical results of an inter-laboratory test – Sodium (Na) ............................................. 26

Table A.5 — Statistical results of an inter-laboratory test – Phosphorus (P) ....................................... 27

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SIST EN 15621:2017
EN 15621:2017 (E)

Table A.6 — Statistical results of an inter-laboratory test – Sulphur (S) ................................................ 28

Table A.7 — Statistical results of an inter-laboratory test – Cobalt (Co) ................................................ 29

Table A.8 — Statistical results of an inter-laboratory test – Copper (Cu) .............................................. 30

Table A.9 — Statistical results of an inter-laboratory test – Iron (Fe)..................................................... 31

Table A.10 — Statistical results of an inter-laboratory test – Manganese (Mn) .................................. 32

Table A.11 — Statistical results of an inter-laboratory test – Molybdenum (Mo) ............................... 33

Table A.12 — Statistical results of an inter-laboratory test – Zinc (Zn) .................................................. 34

Table A.13 — Statistical results of an inter-laboratory test – Cadmium (Cd) ....................................... 35

Table A.14 — Statistical results of an inter-laboratory test – Arsenic (As) ........................................... 36

Table A.15 — Statistical results of an inter-laboratory test – Lead (Pb) ................................................ 37

Annex B (informative) Notes on the detection technique, interferences and quantification,

pressure digestion ........................................................................................................................................ 38

B.1 General ............................................................................................................................................................. 38

B.2 Interferences .................................................................................................................................................. 38

B.2.1 General ............................................................................................................................................................. 38

B.2.2 Spectral line interference .......................................................................................................................... 38

B.2.3 Ionization interferences ............................................................................................................................. 38

B.2.4 Physical interferences ................................................................................................................................ 38

B.3 Quantification and matrix matching ...................................................................................................... 39

B.3.1 General ............................................................................................................................................................. 39

B.3.2 Calibration curve .......................................................................................................................................... 39

B.3.3 Matrix matching ............................................................................................................................................ 39

B.3.4 Standard addition ......................................................................................................................................... 39

B.4 Pressure digestion conditions ................................................................................................................. 40

B.4.1 General ............................................................................................................................................................. 40

B.4.2 Initial sample mass and acid volumes................................................................................................... 40

B.4.3 Digestion temperature ............................................................................................................................... 40

B.4.4 Digestion time ................................................................................................................................................ 40

B.4.5 Digestion solution......................................................................................................................................... 40

B.4.6 Blank solution ................................................................................................................................................ 40

Bibliography ................................................................................................................................................................. 41

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SIST EN 15621:2017
EN 15621:2017 (E)
European foreword

This document (EN 15621:2017) has been prepared by Technical Committee CEN/TC 327 “Animal

feeding stuffs: Methods of sampling and analysis”, the secretariat of which is held by NEN.

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 February 2018, and conflicting national standards

shall be withdrawn at the latest by February 2018.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 15621:2012.

WARNING — The method described in this standard implies the use of reagents that pose a hazard to

health. The standard does not claim to address all associated safety problems. It is the responsibility of

the user of this standard to take appropriate measures for the health and safety protection of the

personnel prior to use of the standard and to ensure that regulatory and legal requirements are

complied with.

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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
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SIST EN 15621:2017
EN 15621:2017 (E)
1 Scope

This European Standard specifies a method for the determination of the elements calcium, sodium,

phosphorus, magnesium, potassium, sulphur, iron, zinc, copper, manganese and cobalt in animal

feeding stuffs by inductively coupled plasma atomic emission spectrometry (ICP-AES) after pressure

digestion.

The method was fully statistically tested and evaluated for the elements calcium, sodium, phosphorus,

magnesium, potassium, sulphur, iron, zinc, copper, manganese and cobalt within the following 11

animal feeds: 2 complete feeds (pig feed, sheep feed), 3 complementary feeds (3 mineral feeds), 1

mineral premixture, 3 feed materials (MgO, phosphate, CaCO ) and 2 feed additives (CuSO , bentonite).

3 4

For elements with a HORRAT values higher than 2 (e.g. potassium and sulphur, see Annex A), the

method is more applicable as a screening method and not for confirmatory purposes.

Other elements like molybdenum, lead, cadmium, arsenic were not fully statistically tested and

evaluated within 11 animal feeding stuff samples because these elements did not occur in

concentrations higher than the limit of quantification in most of these samples. A single laboratory

validation is therefore necessary for the use of this multi element method for these elements.

For the determination of extractable lead in minerals and feeds, containing phyllosilicates (e.g. kaolinite

clay) wet digestion with nitric acid should be used.

The method limit of quantification for each element is dependent on the sample matrix as well as on the

instrument. The method is not applicable for determination of low concentrations of elements. A limit of

quantification of 1 mg/kg should normally be obtained.

NOTE 1 This method can also be used for the determination of minerals in products with high mineral content

(>5 %). For this purpose the accuracy of the method has to be checked individually. Other more matrix-specific

analytical techniques are also available.

NOTE 2 Results using this European Standard EN 15621 may be higher than those obtained when applying

EN 15510 as pressure digestion is used in EN 15621.
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 ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696)

EN ISO 6498, Animal feeding stuffs - Guidelines for sample preparation (ISO 6498)

3 Terms and definitions

For the purposes of this document the terms and definitions given in the European legislation apply.

4 Principle

For the determination of calcium, sodium, phosphorus, magnesium, potassium, sulphur, iron, zinc,

copper, manganese, cobalt, molybdenum, lead, cadmium and arsenic a test portion of the sample is

digested under pressure.

The concentration of the elements is determined by inductively coupled plasma atomic emission

spectrometry (ICP-AES) using external calibration or standard addition technique.

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SIST EN 15621:2017
EN 15621:2017 (E)
5 Reagents

Use only reagents of recognized analytical grade, and water conforming to grade 2 of EN ISO 3696.

WARNING —The use of this European Standard can involve hazardous materials, operations and

equipment. This standard does not purport to address all the safety problems associated with its use. It

is the responsibility of the user of this European Standard to establish appropriate safety and health

practices and determine the applicability of regulatory limitations prior to use.

5.1 Nitric acid, concentrated, not less than 65 % (m/m), c(HNO ) = 14,4 mol/l, having a density of

approximately ρ (HNO ) 1,42 g/ml.

5.2 Nitric acid solution of 2 % (v/v), to be prepared: pipette 20 ml nitric acid concentrated (5.1) in a

1 000 ml volumetric flask (6.4) and fill to the mark with water.
5.3 Hydrogen peroxide, not less than 30 % (m/m).
5.4 Element stock solutions
Ca, Na, P, Mg, K, S, Fe, Zn, Cu, Mn, Co, Mo, Cd, Pb, As
c = 1 000 mg/l.

The user should choose a suitable stock solution. Both single-element stock solutions and multi-element

stock solutions with adequate specification stating the acid used and the preparation technique are

commercially available. It is advisable to use certified stock solutions.

NOTE Element stock solutions with concentrations different from 1 000 mg/l are also acceptable.

5.5 Standard solutions

Depending on the scope, different multi-element standard solutions may be necessary. In general, when

combining multi-element standard solutions, their chemical compatibility and the possible hydrolysis of

the components shall be regarded. Spectral interferences from other elements present in multi-element

standards also need to be considered.

Various combinations of elements at different concentrations can be used, provided that the stock

solutions (5.4) are diluted with the same acid and equal concentration as the acid in the test solution to

a range of standards that covers the concentrations of the elements to be determined.

The multi-element standard solutions are considered to be stable for several months, if stored in the

dark.
6 Apparatus
Usual laboratory apparatus and, in particular, the following:

NOTE For the determination of sodium in low concentrations it is advisable not to use glassware since

glassware can be a source of sodium contamination.
6.1 Laboratory grinder

6.1.1 Laboratory grinder, capable of grinding to a particle size of less than or equal to 0,5 mm, e.g. a

knife mill or equivalent.

6.1.2 Laboratory grinder, capable of grinding to a particle size of less than or equal to 0,1 mm, e.g. a

ball mill or equivalent.
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SIST EN 15621:2017
EN 15621:2017 (E)

NOTE Elements in the sample (e.g. adsorption, contamination) which have to be analysed.

6.2 Analytical balance, capable of weighing to an accuracy of 1 mg.
6.3 Pressure digestion apparatus, commercially available.

The apparatus shall be tested for safety pressure vessels made of acid-resistant materials and having

holders for the sample of acid-resistant material with low level of contamination by elements to be

determined. Apparatus is available which uses a high-pressure incinerator with or without ambient

autoclave pressure.

Instead of polytetrafluoroethylene (PTFE) holders, it is better to use graduated quartz holders,

fluorinated ethylene propylene (FEP) holders or perfluoroalkoxy (PFA) holders. Quartz is advisable to

be used for decomposition temperatures above 230 °C.
6.4 One-mark volumetric flasks, of capacity 1 000 ml.
6.5 Inductively coupled plasma – Atomic Emission Spectrometer.

The instrument shall be equipped with radial plasma as a minimum requirement; axial plasma is

equally acceptable. Background correction shall also be performed when necessary. Settings of the

working conditions (e.g. viewing height, gas flows, RF or plasma power, sample uptake rate, integration

time, and number of replicates) shall be optimized according the manufacturer’s instructions.

6.6 Freeze drying equipment, capable of freeze-drying liquid animal feeding stuffs.

6.7 Oven for pre-drying, capable to hold a temperature of (70 ± 5) °C
6.8 Breaker, of capacity 250ml
6.9 Electric hot plate, with temperature control
7 Sampling

Sampling is not part of the method specified in this International Standard. A recommended sampling

method is given in EN ISO 6497 [1].

It is important that the laboratory receives a sample which is truly representative and has not been

damaged or changed during transport or storage.
8 Preparation of the test sample
8.1 General
Prepare the test sample in accordance with EN ISO 6498:

— The grinding must be done in conditions such that the substance is not appreciably heated and that

no contamination takes place by the grinding tools;

— The operation is to be repeated as many times as is necessary and it must be effected as quickly as

possible in order to prevent any gain or loss of constituents (water);

— The whole ground product is placed in a flask made of e.g. polypropylene, which can be stoppered

and stored in such way to prevent any change in composition;
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SIST EN 15621:2017
EN 15621:2017 (E)

— Before any weighing is carried out for the analysis, the whole test sample must be thoroughly

mixed for reasons of homogeneity. Since a maximum of 0,5 g of sample is used for the digestion it is

of the utmost importance to have a homogeneous sample in order to take a representative sub

sample.
8.2 Animal feeding stuffs which can be ground as such

Grind the laboratory sample (usually 500 g), using a laboratory grinder (6.1.2) or mortar until a particle

size of 0,5 mm or less has been reached.
8.3 Liquid animal feeding stuffs
8.3.1 General

Liquid feeding stuffs shall be pre-dried according to the procedure described in 8.3.2 or freeze-dried

according to the procedure described in 8.3.3.
8.3.2 Pre-drying

Pre-dry the laboratory sample at a temperature of (70 5) °C during at least 16 h to reduce the

moisture content using an oven (6.7). The mass of the sample before and after the pre-drying is to be

determined using an analytical balance (6.2). Grind the pre-dried sample in accordance with 8.2.

8.3.3 Freeze-drying

Freeze-dry the laboratory sample following the instructions of the freeze-drying equipment (6.6). The

mass of the sample before and after the freeze-drying is to be determined using an analytical balance

(6.2). Grind the freeze-dried sample in accordance with 8.2.

Mineral, except mineral products containing crystalline water, e.g. MgCl .6H O, shall be ground using a

2 2

laboratory grinder (6.1.2) or mortar until a particle size of 0,5 mm or less has been reached. Mineral

products containing crystalline water should not be ground.
9 Procedure

9.1 Pressure digestion – Preparation of the blank test solution and the test solution

9.1.1 General

Match the initial sample mass to the capacity of the digestion vessel, with the manufacturer's

instructions being strictly observed for safety reasons. Determine the necessary digestion temperature

and digestion time (EN ISO 13805 [2], see Annex B).
9.1.2 Example of microwave digestion

When using 100 ml vessels, weigh about 0,5 g of the prepared test sample to the nearest 1 mg. Add 3 ml

of nitric acid (5.1) and 0,5 ml of hydrogen peroxide (5.3), seal the digestion vessel and the pressure

holders in the correct manner. Leave to pre-digest outside the microwave for about 30 min. Apply low

microwave energy at the beginning of the digestion and slowly raise the energy to the maximum power,

e.g. start with 100 W, raise up to 600 W within 5 min, hold for 5 min, raise to 1 000 W, hold for 10 min,

cool down for minimum 20 min to 25 min. Treat a blank in the same way.

Dilute the digestion solution accordingly with water. The solution obtained after dilution is called the

test solution. Proceed in accordance with 9.2.
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SIST EN 15621:2017
EN 15621:2017 (E)
9.1.3 Example of a high pressure digestion

When using a 100 ml vessel, weigh about 0,5 g of the prepared test sample to the nearest 1 mg. Add

3 ml of nitric acid (5.1), seal the digestion vessel and the pressure vessel in the correct manner and heat

from room temperature to 150 °C in 60 min, then to 300 °C in 40 min and keep 300 °C for 90 min before

cooling down. Treat a blank in the same way.

Dilute the digestion solution accordingly with water. The solution obtained after dilution is called the

test solution. Proceed in accordance with 9.2.

9.2 Extractable lead in minerals and feeds containing phyllosilicates (e.g. kaolinite clay)

– extraction with diluted nitric acid

Weigh about 2 g of the prepared test sample to the nearest 1 mg into a beaker of 250 ml. Add 16 ml

diluted nitric acid (1 volume of concentrated nitric acid, not less than 65 % mass fraction with 1 volume

of water). Add about 70 ml of water. Cover the beaker (6.8) with a watch-glass and boil for 30 min on an

electric hot plate with temperature control (6.9). Allow to cool. Transfer the liquid into a 100 ml

volumetric flask (6.4), rinse the beaker and the watch-glass several times with water. Dilute to the mark

with water. After homogenizing, filter through a dry folded filter paper into a dry conical flask. Use the

first portion of the filtrate to rinse the glassware and discard that part. If the determination is not

carried out immediately, the conical flask with the filtrate shall be stoppered. Treat a blank in the same

way.
9.3 Calibration
9.3.1 General

Calibration shall be performed by means of external calibration or standard addition technique. In

general the calibration curve should be linear. Using a nonlinear calibration function is possible if it is

well-described, except when using the standard addition. Appropriate matrix matching of the

calibration solutions shall be performed if an external calibration method is used (see Annex B).

9.3.2 External calibration

The calibration is performed with at least two calibration solutions, of which, one is a blank calibration

solution. If the working range is not linear, the calibration should be performed with a blank calibration

solution and at least three equidistant calibration solutions.
9.3.3 Standard addition technique

The standard addition curve should consist of at least two points, of which, one is an addition. For those

elements whose concentration is near the limit of quantification, the standard addition curve should

consist of at least four points, of which, three are additions. If three additions are used, the

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