SIST EN ISO 15151:2020

SLOVENSKI STANDARD
oSIST prEN ISO 15151:2020
01-marec-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: prEN ISO 15151
ICS:
67.100.10 Mleko in predelani mlečni Milk and processed milk
proizvodi products
oSIST prEN ISO 15151:2020 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 15151:2020

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oSIST prEN 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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oSIST prEN 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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oSIST prEN 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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oSIST prEN 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.
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oSIST prEN 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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oSIST prEN ISO 15151:2020

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oSIST prEN 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
a
Lower analytical range ,
20 0,03 0,5 3 0,01 15 10 10 0,2
in mg/100 g
a
Upper analytical range ,
1 280 1,2 20 110 1,0 800 2 000 850 18
in mg/100 g
a
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/
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oSIST prEN 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 %.
3
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).
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oSIST prEN 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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oSIST prEN 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.
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oSIST prEN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
9.1.3 Dried milk, dried whey, infant formula, butter and cheese
Weigh to the nearest 1 mg, 1 g of prepared test sample (8.2) or 0,5 g butter or 0,5 g to 0,8 g cheese (8.3)
in the microwave vessel (6.7) for pressurized digestion. Weigh to the nearest 1 mg, 0,4 g to 0,5 g of
prepared test sample (8.2) or 0,3 g butter or 0,3 g cheese (8.3) into a digestion tube.
If the repeatability in the samples does not meet the criteria, make a pre-step to reduce variation of
homogeneity. Dissolve 25 g powder in 200 g water and then take an aliquot for analysis.
9.1.4 Blank test
In parallel with the procedure of the test portion, carry out a blank test using the same procedure and
the same amount of each reagent being added in the decomposition (9.2) and the determination (9.3)
steps of the test portion.
The added quantities may be modified.
9.2 Decomposition of organic matter
9.2.1 Wet digestion
9.2.1.1 General
Either use pressurized microwave assisted wet digestion system (6.7) or any appropriate
instrumentation for wet digestion.
9.2.1.2 Pressurized microwave assisted wet digestion system with internal standard
Place the vessels containing the test sample (9.1.2 or 9.1.3) and blank (9.1.4) in a fume cupboard. Add
10 ml of nitric acid (5.2) and 0,125 ml of internal standard solution (5.6). Swirl gently and wait a few
min before closing the vessel. Place the vessel into the microwave oven (6.7). Apply the decomposition
programme with the pressurized system mentioned in Table 2.
Table 2 — Decomposition programme for pressurized microwave assisted digestion system
Step Outset power Time Final temperature Cooling system
W min °C
1 max. 1 800 20 180 to 200 Low
2 max. 1 800 35 180 to 200 Low
3 0 15 < 50 High
NOTE The parameters, such as type and volume of reagent to be added, the microwave power and
decomposition time, can be modified according to the type and size of test sample to analyse.
9.3 Determination
9.3.1 Preparation of the test solution
9.3.1.1 Wet digestion with internal standard
Cool the digested solution (9.2.1.2) to room temperature while reducing to atmospheric pressure.
Add 0,5 ml of H O (5.7) to all tubes except the blanks, to neutralize the nitric vapour. Transfer the
2 2
content of the tube quantitatively in a sampler tube. Dilute to 25 ml with water. Mix thoroughly. If
necessary continue with the dilution procedure in 9.3.1.2.
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oSIST prEN ISO 15151:2020
ISO 15151:2018(E)
IDF 229:2018(E)
9.3.1.2 Dilution
According to the type of test sample and element measured, dilute (dilution factor f ) the test solution
1
(9.3.1.1) by using the micropipette (6.4) in the required one-mark volumetric flasks (6.2).
NOTE The concentration of nitric acid in the test solution after dilution is generally that of the nitric acid
solution (5.3).
9.3.2 ICP-AES measurement
9.3.2.1 General
Establish analytical lines, selectivity, limits of determination and quantification, precision, linear
working area and interferences before operating the ICP-AES system.
Set the spectrometer at the required wavelength depending on the element (analyte) of the
determination (see Annex B). Each value is the average from at least three individual measurements of
the test sample and standard solutions. Average the values if falling within an accepted range.
NOTE An ionization buffer can be used if applicable.
9.3.2.2 Calibration
The volumes and corresponding concentrations in Table 3 are given for guidance. Select both within
the linear range of the particular instrument used (at least five concentrations including zero member).
Transfer the volumes of the solutions mentioned in Table 3 with a pipette (6.3 or 6.4) in six volumetric
flasks of 100 ml (6.2) respectively. Dilute with water to the mark and mix. The obtained calibration
solutions are given in Table 3.
Calibration solution shall have the same HNO concentration as the test solution after dilution (9.3.1.2).
3
Table 3 — Pipette scheme for calibration solutions and concentration of each element
Pipette (ml) Concentration (mg/l)
Flask number Element solution Flask number
1 2 3 4 5 6 1 2 3 4 5 6
0 1 2 3 4 5 Ca (5.4) 0 100 200 300 400 500
0 1 2 3 4 5 K (5.4) 0 100 200 300 400 500
0 1 2 3 4 5 P (5.4) 0 100 200 300 400 500
0 3 6 9 12 15 Na (5.4) 0 30 60 90 120 150
0 2 4 6 8 10 Mg (5.4) 0 20 40 60 80 100
0 1 2 3 4 5
...