EN 15550:2017

SLOVENSKI STANDARD
01-oktober-2017
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SIST EN 15550:2008
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Animal feeding stuffs: Methods of sampling and analysis - Determination of cadmium and
lead by graphite furnace atomic absorption spectrometry (GF-AAS) after pressure
digestion
Futtermittel - Probenahme und Untersuchungsverfahren - Bestimmung von Cadmium
und Blei mittels Graphitrohrofen-Atomabsorptionsspektrometrie (GF-AAS) nach
Druckaufschluss
Aliments des animaux - Méthodes d'échantillonnage et d'analyse - Dosage du cadmium
et du plomb par spectrométrie d'absorption atomique à l'aide d'un four graphite après
minéralisation sous pression
Ta slovenski standard je istoveten z: EN 15550:2017
ICS:
65.120 Krmila Animal feeding stuffs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 15550
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2017
EUROPÄISCHE NORM
ICS 65.120 Supersedes EN 15550:2007
English Version
Animal feeding stuffs: Methods of sampling and analysis -
Determination of cadmium and lead by graphite furnace
atomic absorption spectrometry (GF-AAS) after pressure
digestion
Aliments des animaux - Méthodes d'échantillonnage et Futtermittel - Probenahme und
d'analyse - Dosage du cadmium et du plomb par Untersuchungsverfahren - Bestimmung von Cadmium
spectrométrie d'absorption atomique à l'aide d'un four und Blei mittels Graphitrohrofen-
graphite après minéralisation sous pression Atomabsorptionsspektrometrie (GF-AAS) nach
Druckaufschluss
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 15550:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 5
5 Reagents . 5
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 . 7
8.3 Liquid animal feeding stuffs . 8
8.3.1 General . 8
8.3.2 Pre-drying . 8
8.3.3 Freeze-drying . 8
8.4 Mineral matrices . 8
9 Procedure. 8
9.1 Digestion . 8
9.1.1 General . 8
9.1.2 Pressure digestion . 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
9.4.1 General . 9
9.4.2 Determination by AAS graphite furnace – atomic absorption spectrometry . 9
10 Calculation and expression of the result . 10
11 Precision . 10
11.1 Inter-laboratory test . 10
11.2 Repeatability . 10
11.3 Reproducibility . 10
12 Test report . 12
Annex A (informative) Results of the inter-laboratory tests . 13
Annex B (informative) Notes on the detection technique, interferences and quantification,
and pressure digestion . 16
Bibliography . 18

European foreword
This document (EN 15550:2017) 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 15550:2007.
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.

1 Scope
This European Standard specifies a method for the determination of the elements cadmium and lead in
animal feeding stuffs by graphite furnace atomic absorption spectrometry (GF-AAS) after pressure
digestion.
The method was successfully tested in the range of 0,015 mg/kg to 5,65 mg/kg for Cd and 0,18 mg/kg
to 40,3 mg/kg for lead in 11 animal feeds: 2 complete feeds (pig feed, sheep feed), 2 complementary
feeds (2 mineral feeds), 1 mineral premixture, 4 feed materials (MgO, 2 phosphates, CaCO ) and 2 feed
additives (CuSO , bentonite).
For the determination of extractable lead in minerals and feeds, containing phyllosilicates (e.g. kaolinite
clay) wet digestion with diluted nitric acid should be used.
The method limit of quantification for each element is dependent on the sample matrix as well as the
instrument. For cadmium a limit of quantification of 0,05 mg/kg should normally be obtained while for
lead, a limit of quantification of 0,5 mg/kg should be obtained.
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 following terms and definitions apply.
3.1
limit of detection
(LOD)
concentration (mass fraction) derived from the smallest measure that can be detected with reasonable
certainty for a given analytical procedure
Note 1 to entry: xLOD denotes the limit of detection expressed as concentration (mass fraction).
[SOURCE: ISO 11843-1, see [1]]
Note 2 to entry: For analytical systems where the validation range does not include or approach it, the detection
limit does not need to be part of a validation.
[SOURCE: IUPAC 2002, see [2]]
Note 3 to entry: The various conceptual approaches to the subject depend on the estimate of precision at or
near zero concentration (mass fraction) under repeatability or reproducibility conditions.
3.2
limit of quantification
(LOQ)
lowest concentration (mass fraction) determined with satisfactory measurement uncertainty
Note 1 to entry: x denotes the limit of quantification expressed as concentration (mass fraction)
LOQ
[SOURCE: ISO 11843-1, see [1]]
Note 2 to entry: It is useful to state a concentration (mass fraction) below which the analytical method cannot
operate with an acceptable precision. Such precision is arbitrarily defined as relative standard deviation of 10 %.
Note 3 to entry: Usually the limit is set as a fixed multiple (e.g. 3.3) of the detection limit.
Note 4 to entry: Measurements below LOQ are not devoid of information content and are fit for purpose.
[SOURCE: IUPAC 2002, see [2]]
3.3
feed additives
substances that comply with the definition of feed additives given in the Regulation (EC) No 1831/2003
of the European Parliament and of the Council of 22 September 2003 on additives for use in animal
nutrition [3]
3.4
animal feeding stuffs
substances that comply with the definition of animal feeding stuffs given in the Regulation (EC)
No 178/2002 [4]
4 Principle
For the determination of the elements cadmium and lead, a test portion of the sample is digested under
pressure.
The concentration of the elements is determined by graphite furnace atomic absorption spectrometry
(GF-AAS) using external calibration.
The method detection limit for each element is dependent on the sample matrix as well as the
instrument, the type of atomizer and the use of chemical modifiers. A typical sample volume of 10 µl to
20 µl is used.
5 Reagents
Use only reagents of recognized analytical grade, and water conforming to grade 2 of EN ISO 3696.
WARNING — 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 % (mass fraction), c(HNO ) = 14,4 mol/l, having a
density of approximately ρ (HNO ) = 1,42 g/ml.
5.2 Hydrogen peroxide, mass fraction not less than 30 %.
5.3 Element stock solutions
Cd, Pb
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 specifications stating the acid used and the preparation technique are
commercially available. It is advisable to use certified stock solutions.
Stock solutions should not be used after expiration dates.
Element stock solutions with concentrations different from 1 000 mg/l may also be used.
5.4 Calibration solutions
Prepare a range of standards including a blank calibration solution, which covers the linear range of the
element to be determined by diluting the element stock solutions (5.3). Appropriate matrix matching of
the calibration solutions shall be performed (see Annex B), e.g. adjust the acid concentration of the
standards to the acid concentration of the samples. Dilute to volume with water.
5.5 Matrix modifier (e.g. Palladium nitrate/magnesium nitrate modifier)
Pd(NO ) solution (Pd-nitrate solution) is commercially available (mass concentration 10 g/l). Dissolve
3 2
0,259 g of Mg(NO ) 6H 0 (Mg-nitrate solution) in 100 ml of water. Mix the Pd-nitrate solution with
3 2 2
twice as much Mg-nitrate solution. Ten µl of the mixed solution is equal to 15 µg Pd and 10 µg Mg(NO ) .
3 2
It is advisable to use this solution for not longer than one week.
NOTE The combination of Pd and Mg(NO3) is regarded as a “universal” modifier that is used for many
elements. Other possible matrix modifiers are e.g. palladium nitrate modifier and ammonium dihydrogen
phosphate modifier.
5.6 Purge and protective gas, Argon, Ar purity not less than 99,99 % by volume.
6 Apparatus
The usual laboratory apparatus and, in particular, the following should be used:
6.1 Laboratory Grinder
6.1.1 laboratory grinder that is equipped so that samples cannot be contaminated
6.1.2 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
6.1.3 laboratory grinder capable of grinding to a particle size of less than 0,5 mm or less than
0,1 mm for mineral matrices, e.g. a ball mill or equivalent
6.1.4 mortar with pestle, free of contamination
6.2 Analytical balance, capable of weighing with 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 a low level of contamination. Apparatus are
available that uses a high-pressure incinerator with or without ambient autoclave pressure.
Instead of polytetrafluoroethylene (PTFE) holders, it is better to use graduated quartz holders,
perfluoro ethylene propylene (FEP) holders or perfluoroalkoxy (PFA) holders. Quartz is advisable to be
used for decomposition temperatures above 230 °C.
6.4 Graphite furnace atomic absorption spectrometer, with background correction, e.g. Zeeman,
supplied with auto sampler, an appropriate gas (5.6) supply and hollow cathode lamps or EDL-lamps
for lead and cadmium
NOTE It is necessary to place an exhaust venting system over the furnace to remove any smoke and vapours
that might be harmful.
6.5 Graphite tubes, pyrolytically coated and preferably with platforms
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 One mark volumetric flasks, of capacities 100, 1 000 ml
6.9 Breaker, of capacity 250 ml
6.10 Electric hot plate, with temperature control
7 Sampling
Sampling is not part of the method specified in this document. A recommended sampling method is
given in EN ISO 6497 [5].
NOTE It is important that the laboratory receives a sample that 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.
— Grinding must be done in conditions such that the substance is not appreciably heated.
— 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 cons
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