Milk, milk products, infant formula and adult nutritionals - Determination of minerals and trace elements - Inductively coupled plasma atomic emission spectrometry (ICP-AES) method (ISO 15151:2018)

This document specifies a method for the quantitative determination of calcium (Ca), copper (Cu), iron
(Fe), magnesium (Mg), manganese (Mn), phosphorus (P), potassium (K), sodium (Na) and zinc (Zn)
using inductively coupled plasma atomic emission spectrometry (ICP-AES). The method is applicable
for milk, dried milk, butter, cheese, whey, dried whey, infant formula and adult nutritional formula in
the ranges given in Table 1.

Milch, Milcherzeugnisse, Säuglingsnahrung und Nahrungsergänzungsmittel für Erwachsene - Bestimmung von Mineralien und Spurenelementen - Verfahren mit induktiv gekoppelter Plasma-Atomemissionsspektrometrie (ICP-AES) (ISO 15151:2018)

Dieses Dokument legt ein Verfahren für die quantitative Bestimmung von Calcium (Ca), Kupfer (Cu), Eisen (Fe), Magnesium (Mg), Mangan (Mn), Phosphor (P), Kalium (K), Natrium (Na) und Zink (Zn) mittels induktiv gekoppelter Plasma-Atomemissionsspektrometrie (ICP-AES) fest. Das Verfahren ist auf Milch, Trockenmilch, Butter, Käse, Molke, Trockenmolke, Säuglingsnahrung und Nahrungsergänzungsmittel für Erwachsene in den in Tabelle 1 angegebenen Bereichen anwendbar.

Lait, produits laitiers, formules infantiles et produits nutritionnels pour adultes - Détermination de la teneur en minéraux et en oligo-éléments - Méthode par spectrométrie d'émission atomique avec plasma induit par haute fréquence (ICP-AES) (ISO 15151:2018)

Le présent document spécifie une méthode de détermination quantitative de la teneur en calcium (Ca), cuivre (Cu), fer (Fe), magnésium (Mg), manganèse (Mn), phosphore (P), potassium (K), sodium (Na) et zinc (Zn) par spectrométrie d'émission atomique avec plasma induit par haute fréquence (ICP-AES). La méthode est applicable au lait, au lait en poudre, au beurre, au fromage, au lactosérum, au lactosérum en poudre, aux formules infantiles et aux produits nutritionnels pour adultes dans les plages données dans le Tableau 1.

Mleko, mlečni proizvodi, hrana za dojenčke in prehranska dopolnila za odrasle - Določevanje mineralov in elementov v sledovih - Atomska emisijska spektrometrija z induktivno sklopljeno plazmo (ICP-AES) (ISO 15151:2018)

General Information

Status
Published
Public Enquiry End Date
19-Mar-2020
Publication Date
18-Jun-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
11-Jun-2020
Due Date
16-Aug-2020
Completion Date
19-Jun-2020

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SLOVENSKI STANDARD
SIST EN ISO 15151:2020
01-julij-2020
Mleko, mlečni proizvodi, hrana za dojenčke in prehranska dopolnila za odrasle -
Določevanje mineralov in elementov v sledovih - Atomska emisijska
spektrometrija z induktivno sklopljeno plazmo (ICP-AES) (ISO 15151:2018)

Milk, milk products, infant formula and adult nutritionals - Determination of minerals and

trace elements - Inductively coupled plasma atomic emission spectrometry (ICP-AES)

method (ISO 15151:2018)
Milch, Milcherzeugnisse, Säuglingsnahrung und Nahrungsergänzungsmittel für

Erwachsene - Bestimmung von Mineralien und Spurenelementen - Verfahren mit induktiv

gekoppelter Plasma-Atomemissionsspektrometrie (ICP-AES) (ISO 15151:2018)

Lait, produits laitiers, formules infantiles et produits nutritionnels pour adultes -

Détermination de la teneur en minéraux et en oligo-éléments - Méthode par

spectrométrie d'émission atomique avec plasma induit par haute fréquence (ICP-AES)

(ISO 15151:2018)
Ta slovenski standard je istoveten z: EN ISO 15151:2020
ICS:
67.050 Splošne preskusne in General methods of tests and
analizne metode za živilske analysis for food products
proizvode
67.100.10 Mleko in predelani mlečni Milk and processed milk
proizvodi products
67.230 Predpakirana in pripravljena Prepackaged and prepared
hrana foods
SIST EN ISO 15151:2020 en

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

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SIST EN ISO 15151:2020
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SIST EN ISO 15151:2020
EN ISO 15151
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2020
EUROPÄISCHE NORM
ICS 67.100.10
English Version
Milk, milk products, infant formula and adult nutritionals -
Determination of minerals and trace elements -
Inductively coupled plasma atomic emission spectrometry
(ICP-AES) method (ISO 15151:2018)

Lait, produits laitiers, formules infantiles et produits Milch, Milcherzeugnisse, Säuglingsnahrung und

nutritionnels pour adultes - Détermination de la teneur Nahrungsergänzungsmittel für Erwachsene -

en minéraux et en oligo-éléments - Méthode par Bestimmung von Mineralien und Spurenelementen -

spectrométrie d'émission atomique avec plasma induit Verfahren mit induktiv gekoppelter Plasma-

par haute fréquence (ICP-AES) (ISO 15151:2018) Atomemissionsspektrometrie (ICP-AES) (ISO

15151:2018)
This European Standard was approved by CEN on 10 May 2020.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, 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: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15151:2020 E

worldwide for CEN national Members.
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SIST EN ISO 15151:2020
EN ISO 15151:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 15151:2020
EN ISO 15151:2020 (E)
European foreword

The text of ISO 15151:2018 has been prepared by Technical Committee ISO/TC 34 "Food products” of

the International Organization for Standardization (ISO) and has been taken over as EN ISO 15151:2020

by Technical Committee CEN/TC 302 “Milk and milk products - 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 December 2020, and conflicting national standards

shall be withdrawn at the latest by December 2020.

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.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: 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, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 15151:2018 has been approved by CEN as EN ISO 15151:2020 without any modification.

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SIST EN ISO 15151:2020
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SIST EN ISO 15151:2020
INTERNATIONAL ISO
STANDARD 15151
IDF 229
First edition
2018-11
Milk, milk products, infant
formula and adult nutritionals —
Determination of minerals and trace
elements — Inductively coupled
plasma atomic emission spectrometry
(ICP-AES) method
Lait, produits laitiers, formules infantiles et produits nutritionnels
pour adultes — Détermination de la teneur en minéraux et en oligo-
éléments — Méthode par spectrométrie d'émission atomique avec
plasma induit par haute fréquence (ICP-AES)
Reference numbers
ISO 15151:2018(E)
IDF 229:2018(E)
ISO and IDF 2018
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO and IDF 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office International Dairy Federation
CP 401 • Ch. de Blandonnet 8 Silver Building • Bd Auguste Reyers 70/B
CH-1214 Vernier, Geneva B-1030 Brussels
Phone: +41 22 749 01 11 Phone: +32 2 325 67 40
Fax: +41 22 749 09 47 Fax: +32 2 325 67 41
Email: copyright@iso.org Email: info@fil-idf.org
Website: www.iso.org Website: www.fil-idf.org
Published in Switzerland
ii © ISO and IDF 2018 – All rights reserved
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus ..................................................................................................................................................................................................................... 3

7 Sampling ........................................................................................................................................................................................................................ 4

8 Preparation of test sample ......................................................................................................................................................................... 4

8.1 Milk and whey .......................................................................................................................................................................................... 4

8.2 Dried milk, dried whey and infant formula .................................................................................................................... 4

8.3 Cheese ............................................................................................................................................................................................................. 4

9 Procedure..................................................................................................................................................................................................................... 4

9.1 Test portion ................................................................................................................................................................................................ 4

9.1.1 General...................................................................................................................................................................................... 4

9.1.2 Milk and whey .................................................................................................................................................................... 4

9.1.3 Dried milk, dried whey, infant formula, butter and cheese ......................................................... 5

9.1.4 Blank test ................................................................................................................................................................................ 5

9.2 Decomposition of organic matter ........................................................................................................................................... 5

9.2.1 Wet digestion ...................................................................................................................................................................... 5

9.3 Determination ......................................................................................................................................................................................... 5

9.3.1 Preparation of the test solution .......................................................................................................................... 5

9.3.2 ICP-AES measurement ................................................................................................................................................ 6

10 Calculation and expression of results ............................................................................................................................................. 7

10.1 Calculation .................................................................................................................................................................................................. 7

10.2 Expression of test results ............................................................................................................................................................... 7

11 Precision ....................................................................................................................................................................................................................... 7

11.1 General ........................................................................................................................................................................................................... 7

11.2 Repeatability ............................................................................................................................................................................................. 8

11.3 Reproducibility ....................................................................................................................................................................................... 8

12 Test report ................................................................................................................................................................................................................... 8

Annex A (informative) Precision data ................................................................................................................................................................. 9

Annex B (informative) Notes on the detection technique, interferences and quantification .................23

Bibliography .............................................................................................................................................................................................................................26

© ISO and IDF 2018 – All rights reserved iii
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

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

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO’s adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,

Milk and milk products and the International Dairy Federation (IDF), in collaboration with AOAC

INTERNATIONAL.

It is being published jointly by ISO and IDF and separately by AOAC INTERNATIONAL. The method

described in this document is equivalent to the AOAC Official Method 2011.14: Minerals and Trace

Elements in Infant Formula.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO and IDF 2018 – All rights reserved
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)

IDF (the International Dairy Federation) is a non-profit private sector organization representing the

interests of various stakeholders in dairying at the global level. IDF members are organized in National

Committees, which are national associations composed of representatives of dairy-related national

interest groups including dairy farmers, dairy processing industry, dairy suppliers, academics and

governments/food control authorities.

ISO and IDF collaborate closely on all matters of standardization relating to methods of analysis

and sampling for milk and milk products. Since 2001, ISO and IDF jointly publish their International

Standards using the logos and reference numbers of both organizations.

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

patent rights. IDF shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute and endorsement.

This document was prepared by the IDF Standing Committee on Analytical Methods for Composition

and ISO Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, in

collaboration with AOAC INTERNATIONAL.

It is being published jointly by ISO and IDF and separately by AOAC INTERNATIONAL. The method

described in this document is equivalent to the AOAC Official Method 2011.14: Minerals and Trace Elements

in Infant Formula. All work was carried out by the ISO/IDF Action Team on C17 of the Standing Committee

on Analytical Methods for Composition under the aegis of its project leader, Mr H. Cruijsen (NL).

© ISO and IDF 2018 – All rights reserved v
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SIST EN ISO 15151:2020
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
INTERNATIONAL STANDARD
IDF 229:2018(E)
Milk, milk products, infant formula and adult
nutritionals — Determination of minerals and trace
elements — Inductively coupled plasma atomic emission
spectrometry (ICP-AES) method
1 Scope

This document specifies a method for the quantitative determination of calcium (Ca), copper (Cu), iron

(Fe), magnesium (Mg), manganese (Mn), phosphorus (P), potassium (K), sodium (Na) and zinc (Zn)

using inductively coupled plasma atomic emission spectrometry (ICP-AES). The method is applicable

for milk, dried milk, butter, cheese, whey, dried whey, infant formula and adult nutritional formula in

the ranges given in Table 1.
Table 1 — Analytical ranges
Ca Cu Fe Mg Mn P K Na Zn
Lower analytical range ,
20 0,03 0,5 3 0,01 15 10 10 0,2
in mg/100 g
Upper analytical range ,
1 280 1,2 20 110 1,0 800 2 000 850 18
in mg/100 g
concentrations apply to

— milk and “ready-to-feed” liquids as-is, using a typical sample size of 4 g per final analytical solution volume of 25 ml and

— reconstituted milk powder, infant formula powders and adult nutritional powders (25 g into 200 g of water), using a

typical sample size of mass of the reconstituted slurry per final analytical solution volume of 25 ml.

Ranges for non-reconstituted dairy ingredients (butter, cheese, whey powders, whey protein concentrates) are adjusted

proportionally upward from these values based upon the sample size used for the ingredient. For example, if 0,6 g of cheese

is digested the ranges will be 4 g/0,6 g = 6,7 × higher.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
© ISO and IDF 2018 – All rights reserved 1
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
4 Principle

The organic matter is decomposed by wet digestion using nitric acid in a pressurized microwave

assisted wet digestion system or any other appropriate instrumentation for wet digestion and diluted.

An internal standard is used. The test and calibration solutions are atomized into plasma of an

inductively coupled plasma spectrometer and the emission is measured at appropriate wavelengths

using external calibration.
5 Reagents

WARNING — The use of this document can involve hazardous materials, operations and reagents.

This document does not propose to address all the safety problems associated with its use. It is

the responsibility of the user of this document to establish safety and health practices.

Use only reagents of recognized analytical grade, unless otherwise specified.
5.1 Water, complying with ISO 3696, grade 2, unless otherwise stated.
5.2 Nitric acid (HNO ), concentrated, with a mass fraction of 65 %.

5.3 Nitric acid solution (HNO ), 10 % volume fraction. Add one part of HNO (5.2) to seven parts of

3 3
water and mix.

5.4 Element stock solutions of Ca, P, K (each of mass concentration ρ = 10 000 mg/l) and Cu, Fe, Mg,

Mn, Na, Zn (each of ρ = 1 000 mg/l).

Use a suitable element stock solution, preferably a certified one. Both single-element stock solutions

and multi-element stock solutions with an adequate specification, stating the acid used (mostly being

nitric acid) and the preparation technique, are commercially available. Do not use the element stock

solution after the expiry date.
5.5 Standard solutions.
5.5.1 General

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

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

the components shall be taken into account. The examples given below also consider the measuring

range of various ICP-AES instruments and the expected concentration of the elements in milk and milk

products.

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

(observe the expiry date specified by the manufacturer). Other combinations of elements at different

concentrations may be used, provided that the element stock solutions (5.4) are diluted with the same

acid with a similar concentration that is used for the test solution so as to prepare a range of standards

that covers the concentration of the elements to be determined.

Store the standard working solutions in a high-density polyethylene bottle (6.6) so as to avoid any

contamination.
5.5.2 Standard working solution of Fe, ρ = 400 mg/l

Pipette 20,0 ml of Fe stock solution (5.4) into a 50 ml volumetric flask. Dilute with water to the 50 ml

mark. Transfer the standard working solution to a suitable storage bottle (6.6).
2 © ISO and IDF 2018 – All rights reserved
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)

5.5.3 Standard working solution of Cu, Mn and Zn, ρ = 50 mg Cu, 50 mg Mn and 200 mg Zn/l

Pipette 5,00 ml of Cu, 5,00 ml of Mn and 20,0 ml Zn of the concerned element stock solution (5.4) into a

100 ml volumetric flask. Dilute with water to the 100 ml mark. Transfer the standard working solution

to a suitable storage bottle (6.6).

5.6 Internal standard solution, for example, yttrium, indium or strontium, ρ = 1 000 mg/l.

5.7 H O , with a volume fraction of 30 %.
2 2
6 Apparatus

Clean all glassware and plasticware, including the microwave digestion vessels, thoroughly with the

nitric acid solution (5.3), rinse three times with water (5.1) and allow to dry. Store the clean glassware

and plasticware in a dust-free environment to ensure they are free of any contamination when used.

Usual laboratory apparatus, and in particular, the following.

6.1 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg.

6.2 One-mark volumetric flasks, of different nominal capacity, Class A in accordance with ISO 1042.

6.3 One-mark pipettes, of different nominal capacity, complying with the requirements of ISO 648.

6.4 Micropipettes, capable of adjusting to between 0,100 ml and 1,000 ml and to between 1 ml and

5 ml, with plastic pipette tips.
6.5 Dispenser, capable of dispensing between 1 ml and 10 ml.

6.6 High-density polyethylene bottles, for storing the standard and sample solutions.

6.7 Pressurized microwave assisted wet digestion system, with operator selectable output of

between 0 W and 1 800 W microwave power, provided with temperature and pressure controllers and

an air cooling device, equipped with appropriate vessels of capacity 75 ml, commercially available or

equivalent.
6.8 ICP-AES instrument.

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, radio frequency (RF) or plasma power, sample

uptake rate, integration time, number of replicates] shall be optimized according to the manufacturer’s

instructions.

6.9 Water baths, capable of maintaining a temperature of 20 °C ± 2 °C and 40 °C ± 2 °C.

6.10 Appropriate grinding device.
6.11 Sampler tubes.
6.12 Cyclonic spray chamber.
6.13 Concentric nebulizer.
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SIST EN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
7 Sampling

A representative sample should be sent to the laboratory. It should not be damaged or changed during

transport or storage. Sampling is not part of the method specified in this document. A recommended

[1]
sampling method is given in ISO 707 | IDF 50 .

Store the test sample in such a way that deterioration and change in its composition are prevented.

8 Preparation of test sample
8.1 Milk and whey

Place the test sample in the water bath (6.9) at 20 °C and mix carefully. If, in the case of milk, the fat is

not evenly dispersed, warm the test sample slowly in a water bath (6.9) at 40 °C. Mix gently by inversion

only. When the sample is mixed thoroughly, cool it quickly in the water bath (6.9) at 20 °C.

8.2 Dried milk, dried whey and infant formula

Transfer the test sample into a container of capacity about twice the volume of the sample and provided

with an airtight lid. Close the container immediately. Mix the milk powder thoroughly by repeatedly

shaking and inverting the container.
8.3 Cheese

Remove the rind, smear or mouldy surface layer of the cheese, in such a way as to provide a test sample

representative of the cheese as it is usually consumed. Grind the test sample by means of a grinding

device (6.10). Quickly mix the whole mass and preferably grind the mass again quickly.

If the test sample cannot be ground (e.g. soft cheese), mix the whole sample thoroughly. Transfer the pre-

treated sample, or a representative part of it, immediately into a container provided with an airtight lid.

Analyse the test sample as soon as possible after grinding. Do not examine any ground cheese that

shows unwanted mould growth or has started to deteriorate.
9 Procedure
9.1 Test portion
9.1.1 General

If it is required to check whether the repeatability requirement is met, carry out two single

determinations under repeatability conditions.

WARNING — When using a system running under pressure (e.g. pressurized microwave assisted

wet decomposition system), pay special attention to avoid any risk of explosion. Consider, in

particular, the size of test portion. In a decomposition vessel of about 75 ml, not more of any

sample shall be digested corresponding to an amount of dry matter of 1 g.
9.1.2 Milk and whey

Weigh to the nearest 1 mg, 4 g of prepared test sample (8.1) in the microwave vessel (6.7) or

digestion tube.
4 © ISO and IDF 2018 – All rights reserved
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SIST EN
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