Cosmetics - Analytical methods - Measurement of traces of heavy metals in cosmetic finished products using ICP/MS technique (ISO 21392:2021)

- Selection of the metallic elements of interest
- Selection or development of a reliable method for determination of these elements in cosmetic products which minimizes risk of interferences and allows the appropriate levels to be measured.
- Validation and characterization of the analytical method to assess its performance (global precision) at the appropriate level.

Kosmetische Mittel - Untersuchungsverfahren - Messung von Spuren von Schwermetallen in fertigen kosmetischen Mitteln mittels ICP-MS (ISO 21392:2021)

In diesem Dokument wird ein Verfahren zur Quantifizierung von Spurenanteilen von Schwermetallen in kosmetischen Mitteln bereitgestellt.
Dieses Dokument bezieht sich nur auf Chrom, Cobalt, Nickel, Arsen, Cadmium, Antimon und Blei. Das Verfahren kann auf andere Elemente angewendet werden, es liegt jedoch in der Verantwortung des Analytikers nachzuweisen, dass es für diesen Zweck geeignet ist.

Cosmétiques - Méthodes d’analyse - Mesurage des éléments traces métalliques par ICP-MS dans les produits cosmétiques finis (ISO 21392:2021)

Kozmetika - Analizne metode - Določevanje težkih kovin v sledovih v končnih kozmetičnih izdelkih z masno spektrometrijo z induktivno sklopljeno plazmo (ICP/MS) (ISO 21392:2021)

General Information

Status
Published
Public Enquiry End Date
30-Jun-2020
Publication Date
12-Dec-2021
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
08-Oct-2021
Due Date
13-Dec-2021
Completion Date
13-Dec-2021

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SLOVENSKI STANDARD
SIST EN ISO 21392:2022
01-januar-2022
Kozmetika - Analizne metode - Določevanje težkih kovin v sledovih v končnih
kozmetičnih izdelkih z masno spektrometrijo z induktivno sklopljeno plazmo
(ICP/MS) (ISO 21392:2021)

Cosmetics - Analytical methods - Measurement of traces of heavy metals in cosmetic

finished products using ICP/MS technique (ISO 21392:2021)
Kosmetische Mittel - Untersuchungsverfahren - Messung von Spuren von
Schwermetallen in fertigen kosmetischen Mitteln mittels ICP-MS (ISO 21392:2021)
Cosmétiques - Méthodes d’analyse - Mesurage des éléments traces métalliques par
ICP-MS dans les produits cosmétiques finis (ISO 21392:2021)
Ta slovenski standard je istoveten z: EN ISO 21392:2021
ICS:
71.100.70 Kozmetika. Toaletni Cosmetics. Toiletries
pripomočki
SIST EN ISO 21392:2022 en,fr,de

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

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SIST EN ISO 21392:2022
---------------------- Page: 2 ----------------------
SIST EN ISO 21392:2022
EN ISO 21392
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2021
EUROPÄISCHE NORM
ICS 71.100.70
English Version
Cosmetics - Analytical methods - Measurement of traces of
heavy metals in cosmetic finished products using ICP/MS
technique (ISO 21392:2021)

Cosmétiques - Méthodes d'analyse - Mesurage des Kosmetische Mittel - Untersuchungsverfahren -

éléments traces métalliques par ICP-MS dans les Messung von Spuren von Schwermetallen in fertigen

produits cosmétiques finis (ISO 21392:2021) kosmetischen Mitteln mittels ICP-MS (ISO

21392:2021)
This European Standard was approved by CEN on 2 August 2021.

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

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21392:2021 E

worldwide for CEN national Members.
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SIST EN ISO 21392:2022
EN ISO 21392:2021 (E)
Contents Page

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

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SIST EN ISO 21392:2022
EN ISO 21392:2021 (E)
European foreword

This document (EN ISO 21392:2021) has been prepared by Technical Committee ISO/TC 217

"Cosmetics" in collaboration with Technical Committee CEN/TC 392 “Cosmetics” the secretariat of

which is held by AFNOR.

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 March 2022, and conflicting national standards shall

be withdrawn at the latest by March 2022.

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 has been prepared under a Standardization Request given to CEN by the European

Commission and the European Free Trade Association.

Any feedback and questions on this document should be directed to the users’ national standards

body/national committee. A complete listing of these bodies can be found on the CEN websites.

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 21392:2021 has been approved by CEN as EN ISO 21392:2021 without any modification.

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SIST EN ISO 21392:2022
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SIST EN ISO 21392:2022
INTERNATIONAL ISO
STANDARD 21392
First edition
2021-08
Cosmetics — Analytical methods
— Measurement of traces of heavy
metals in cosmetic finished products
using ICP/MS technique
Cosmétiques — Méthodes d’analyse — Mesurage des éléments traces
métalliques par ICP-MS dans les produits cosmétiques finis
Reference number
ISO 21392:2021(E)
ISO 2021
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SIST EN ISO 21392:2022
ISO 21392:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 21392:2022
ISO 21392:2021(E)
Contents Page

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

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 Principle ........................................................................................................................................................................................................................ 1

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

6 Apparatus and equipment .......................................................................................................................................................................... 2

7 Preparation of standards solutions .................................................................................................................................................. 3

7.1 General ........................................................................................................................................................................................................... 3

7.2 Diluted nitric acid ................................................................................................................................................................................. 3

7.3 Diluting solution .................................................................................................................................................................................... 4

7.4 Internal standard solutions.......................................................................................................................................................... 4

7.4.1 General...................................................................................................................................................................................... 4

7.4.2 Rhodium standard solution, 1 mg/l ................................................................................................................ 4

7.4.3 Lutetium standard solution, 1 mg/l ................................................................................................................ 4

7.5 Standard solutions ............................................................................................................................................................................... 4

7.5.1 General...................................................................................................................................................................................... 4

7.5.2 High concentration mixed standard solution, 10 mg/l ................................................................... 5

7.5.3 Low concentration mixed standard solution, 0,1 mg/l .................................................................. 5

7.6 Calibration blank solution ............................................................................................................................................................. 5

7.7 Calibration solutions .......................................................................................................................................................................... 5

8 Procedure..................................................................................................................................................................................................................... 6

8.1 Preparation of samples .................................................................................................................................................................... 6

8.2 Pressure assisted digestion .......................................................................................................................................................... 6

8.2.1 General...................................................................................................................................................................................... 6

8.2.2 Preparation of sample by digestion — General case ........................................................................ 6

8.2.3 Preparation of sample by digestion — Specific cases ...................................................................... 7

8.2.4 Microwave digestion procedure ......................................................................................................................... 7

8.2.5 Preparation of measurement solutions ....................................................................................................... 8

8.3 Inductively coupled plasma mass spectrometry ....................................................................................................... 8

8.3.1 ICP-MS operating conditions ................................................................................................................................. 8

8.3.2 Quantification of the analytes by ICP-MS .................................................................................................... 8

8.4 Quality control of the analysis ................................................................................................................................................... 9

8.4.1 General...................................................................................................................................................................................... 9

8.4.2 During digestion ............................................................................................................................................................10

8.4.3 During analysis ...............................................................................................................................................................11

8.4.4 Example of ICP-MS sequence .............................................................................................................................11

9 Calculation ...............................................................................................................................................................................................................12

10 Method performance ....................................................................................................................................................................................12

11 Test report ................................................................................................................................................................................................................13

Annex A (informative) Performance of the method determined by the accuracy profile

methodology ..........................................................................................................................................................................................................14

Annex B (informative) Evaluation of the method via ISO 5725 statistical approach ......................................22

Bibliography .............................................................................................................................................................................................................................30

© ISO 2021 – All rights reserved iii
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SIST EN ISO 21392:2022
ISO 21392:2021(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 217, Cosmetics, in collaboration with

the European Committee for Standardization (CEN) Technical Committee CEN/TC 392, Cosmetics, in

accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

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 2021 – All rights reserved
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SIST EN ISO 21392:2022
ISO 21392:2021(E)
Introduction

This document specifies an analytical procedure for the determination of trace levels of heavy metals

(e.g. chromium, cobalt, nickel, arsenic, cadmium, antimony and lead) in finished cosmetic products by

inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion of the sample. This

[9][10][11] [9][10]

type of analytical procedure is widely described in other areas such as environment , food

[11] [12][13][14][15]

and pharmaceutical industry . While it maximizes the detection of trace levels present

in cosmetic products, it does not provide any methodology to directly evaluate systemic exposure of

the consumers.
© ISO 2021 – All rights reserved v
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SIST EN ISO 21392:2022
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SIST EN ISO 21392:2022
INTERNATIONAL STANDARD ISO 21392:2021(E)
Cosmetics — Analytical methods — Measurement of traces
of heavy metals in cosmetic finished products using ICP/
MS technique
1 Scope

This document provides a method for quantification of trace levels of heavy metals in cosmetic products.

This document refers only to chromium, cobalt, nickel, arsenic, cadmium, antimony and lead. The

methodology can apply to other elements, however, it is the responsibility of the analyst to demonstrate

that it fits that purpose.
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 3696, Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

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/
3.1
validation range

range from the upper to the lower concentration of samples used for the method evaluation

3.2
validated range

range of concentrations between the upper and lower levels that the method performance has been

demonstrated to be compliant with the method requirements
4 Principle

Trace levels of heavy metals in cosmetic products are quantified by ICP-MS measurement of the solutions

following digestion of the cosmetic products. Digestion takes place with mineral acids in sealed vessels

heated to 200 °C by microwaves, producing high pressures.

In the sample preparation procedure, cosmetic ingredients are digested by using a nitric acid/

hydrochloric acid mixture allowing the trace levels of heavy metal to be solubilized for measurement.

It is possible that some cosmetic inorganic ingredients, such as silica or titanium dioxide, are not

completely digested under the conditions of this document and that heavy metal confined in such

ingredients are not fully extracted. However, the level of heavy metal trapped in these inorganic

materials is not considered to significantly contribute to the exposure level of consumers to these

heavy metals. The use of ICP-MS ensures reliable measurement of trace levels of heavy metals due to its

proven high sensitivity and selectivity.
© ISO 2021 – All rights reserved 1
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SIST EN ISO 21392:2022
ISO 21392:2021(E)

In order to obtain comparable results, it is absolutely mandatory to follow all the conditions linked to

the digestion of the samples.
5 Reagents

Care shall be taken to assure that the analyte background in the reagents and the water used is

negligible and will not interfere analysis. Unless specified otherwise, solutions are understood to be

aqueous solutions.
-1 [16]

5.1 Water, conforming to Grade 1 of ISO 3696 (conductivity below 0,1 µS.cm at 25 °C ).

5.2 Nitric acid, minimum mass fraction w = 60 %, density = 1,38 g/ml, suitable for ICP-MS analysis.

5.3 Hydrochloric acid, minimum w = 30 %, density = 1,15 g/ml, suitable for ICP-MS analysis.

5.4 Internal standard stock solutions

For storage and stability conditions of the internal standard stock solutions, follow the specifications

of the suppliers. The internal standard solution should contain a certified, or traceable to a certified

reference material (CRM) content.
5.4.1 Rhodium stock solution, 1 000 mg/l.
5.4.2 Lutetium stock solution, 1 000 mg/l.

5.5 Analytes stock solutions [chromium (Cr), cobalt (Co), nickel (Ni), arsenic (As), cadmium

(Cd), antimony (Sb) and lead (Pb)] 1 000 mg/l for each element.

Commercially available single element or mixed stock solutions with a known certified, or traceable

to a CRM content can be used. The used stock solutions shall not contain other elements that could

interfere with the analytes to be quantified.

5.6 ICP-MS tune solution, containing, for example, Ce, Co, Li, Mg, Tl and Y (1 µg/l) according to

instrument manufacturer’s recommendations.
6 Apparatus and equipment

All apparatus and equipment that come into direct contact with sample or solutions shall be pre-cleaned

with diluted nitric acid (see 7.2) and rinsed with ultrapure water (5.1) to ensure the lowest analyte

background. To prevent contamination and adsorption, do not use lab materials made with borosilicate

glass.
6.1 Digestion vessels
6.1.1 General case

Use commercially available, safety-tested pressure vessels and inserts made of acid-resistant, low-

contamination materials. The assembled vessels shall be able to safely withstand temperatures up to at

least 200 °C and pressures up to at least 40 bar.

It is recommended to keep digestion vessel used only for cosmetic analysis purposes to minimize

cross contamination. In addition, the digestion vessels shall always be thoroughly washed after each

use. After digesting highly loaded samples, it is recommended to perform a blank digestion with same

conditions reported in this document to clean vessels before digesting subsequent samples.

2 © ISO 2021 – All rights reserved
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SIST EN ISO 21392:2022
ISO 21392:2021(E)
6.1.2 Special care for quantification of antimony

Antimony has been reported to be prone to adsorb on the inner surface of walls of vessels and adsorption

is empirically known to happen more frequently when using vessels with extensive period of usage.

Use only digestion vessels with minimal surface roughness to prevent antimony adhesion to the vessel

[7],[16]

surface . Thorough examination of the vessels shall be performed before their use to control for

any scratch or damage or any deposit. If there is any doubt on the integrity of vessels inner surface,

consider replacing with brand new digestion vessels.

This issue has been reported to more often happen when polytetrafluoroethylene digestion vessels

are used because they can be easily damaged. Quartz containers are recommended because they are

usually more resistant to attrition. Damage is also more easily visible because of their transparency.

However, polytetrafluoroethylene vessels without any scratch or damage on its inner surface or any

deposit are appropriate.

In case of doubt on the possible adsorption of antimony on vessels’ walls (e.g. if significant deviations

from the target value are observed), a control test is described in 8.4.2.
6.2 Microwave-assisted digestion instruments.

Microwave-heated systems shall be equipped with a temperature measurement unit, which

simultaneously regulates the power control of the microwave. Calibrate the temperature sensor before

use of at least once a year.
6.3 Membrane filter, 0,45 µm pore size.

The membrane filter used shall be suitable for inorganic traces analysis. It shall be inert with regard

to the acid concentration of the measurement solution and shall not bring any contamination into

the measurement solution or adsorption of the analytes. Several types of membrane material are

commercially available [polytetrafluoroethylen (PTFE), polypropylene (PP), etc.] and their fit for

purpose shall be verified by means of appropriate measurements [blanks, quality control (QC) samples,

etc.].
6.4 ICP-MS

Mass spectrometer with inductively coupled argon plasma is composed of a sample introduction and an

atomisation system, as well as an instrument control and evaluation unit. To prevent interferences with

the masses of the heavy metals chromium, nickel, cobalt, arsenic and cadmium, use a mass spectrometer

that is capable of compensating or minimizing such interferences (e.g. collision and/or reaction cell,

resolution above 3 000, alternatively corrective formulae for higher concentrations).

7 Preparation of standards solutions
7.1 General

For all the solutions, the terminology "part" in the standard refers to either volume or weight. That

means that standards and samples can be diluted by volume or weight. However, it should be consistent

for both standards and samples.
7.2 Diluted nitric acid

Produced by mixing nitric acid (5.2) with pure water (5.1) at a ratio of approximately 1 + 9 parts

respectively.
© ISO 2021 – All rights reserved 3
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SIST EN ISO 21392:2022
ISO 21392:2021(E)
7.3 Diluting solution

The diluting solution shall have the same acid composition (total content and acid ratio) as the analytical

solution (the diluted digest solution). This solution should contain:
— 2,5 parts of nitric acid (5.2);
— 0,5 part of hydrochloric acid (5.3);
— 97 parts of water (5.1).
7.4 Internal standard solutions
7.4.1 General

The internal standards (IS) selected should cover all the mass range of the considered analytes and

have similar ionisation energy to the heavy metal for which it is used for correction purposes. It shall

also be checked that the native concentration of the internal standards to be analysed is negligible and

that they are not interfered by sample constituents.

Rhodium and lutetium have proven to be suitable as internal standards. Samples should be checked for

negligible native concentrations and that the sample constituents do not interfere with it.

Rhodium is suitable for the determination of chromium, cobalt, nickel, arsenic, cadmium and antimony,

whereas lutetium is suitable for the determination of lead. Alternatively, other elements may be used

(for example indium or iridium). Scandium, however, is not suitable as IS due to calcium interferences.

An IS with a mass (m/z) below 100 is not recommended because it may suffer from interferences from

matrix components.

Internal standard solutions may be added in each sample and calibration solution at the same

concentration or may be added through an online Y-fitting to a pump tube.

The concentration of the internal standard solutions shall be included in the range 1 mg/l to 2 mg/l. In

7.4.2 and 7.4.3, a concentration of 1 mg/l has been used for all the calculations.

7.4.2 Rhodium standard solution, 1 mg/l

Dilute the rhodium stock solution (5.4.1) 1 + 999 with diluting solution (see 7.3). This internal standard

solution is stable at room temperature for 6 months.
Indium or iridium may also be used as internal standards.
7.4.3 Lutetium standard solution, 1 mg/l

Dilute the Lutetium stock solution (5.4.2) 1 + 999 with diluting solution (see 7.3). This internal standard

solution is stable at room temperature for 6 months.
Indium or iridium may also be used as internal standards.
7.5 Standard solutions
7.5.1 General

The concentrations of these standard solutions are examples and should be adjusted to the specific

conditions in the laboratories.
4 © ISO 2021 – All rights reserved
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SIST EN ISO 21392:2022
ISO 21392:2021(E)
7.5.2 High concentration mixed standard solution, 10 mg/l
Dilute 100 times the analytes stock solution(s) (5.5) by adding:

— in the case of single analyte stock solutions, 1 part of each of these 7 solutions to 93 parts of the

diluting solution (see 7.3);

— in the case of mixed stock solution, add 1 part of this solution to 99 parts of the diluting solution (see

7.3).
This high standard
...

SLOVENSKI STANDARD
oSIST prEN ISO 21392:2020
01-junij-2020
Kozmetika - Analizne metode - Določevanje sledov težkih kovin v končnih
kozmetičnih izdelkih z masno spektrometrijo z induktivno sklopljeno plazmo
(ICP/MS) (ISO/DIS 21392:2020)

Cosmetics - Analytical Methods - Measurement of traces of heavy metals in cosmetic

finished products using ICP/MS technique (ISO/DIS 21392:2020)
Kosmetische Mittel - Untersuchungsverfahren - Messung von Spuren von

Schwermetallen in fertigen kosmetischen Mitteln mittels ICP-MS (ISO/DIS 21392:2020)

Cosmétiques - Méthodes analytiques - Détermination de traces de métaux lourds dans

les produits finis cosmétiques par ICP/MS (ISO/DIS 21392:2020)
Ta slovenski standard je istoveten z: prEN ISO 21392
ICS:
71.100.70 Kozmetika. Toaletni Cosmetics. Toiletries
pripomočki
oSIST prEN ISO 21392:2020 en,fr,de

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

---------------------- Page: 1 ----------------------
oSIST prEN ISO 21392:2020
---------------------- Page: 2 ----------------------
oSIST prEN ISO 21392:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 21392
ISO/TC 217 Secretariat: ISIRI
Voting begins on: Voting terminates on:
2020-04-29 2020-07-22
Cosmetics — Analytical methods — Measurement of traces
of heavy metals in cosmetic finished products using ICP/
MS technique

Cosmétiques — Méthodes analytiques — Détermination de traces de métaux lourds dans les produits finis

cosmétiques par ICP/MS
ICS: 71.100.70
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 21392:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
---------------------- Page: 3 ----------------------
oSIST prEN ISO 21392:2020
ISO/DIS 21392:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 21392:2020
ISO/DIS 21392:2020(E)
Contents Page

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

Introduction ..................................................................................................................................................................................................................................v

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

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

3 Principle ........................................................................................................................................................................................................................ 1

4 Reagents ........................................................................................................................................................................................................................ 1

5 Apparatus and equipment .......................................................................................................................................................................... 2

5.1 Digestion vessels ................................................................................................................................................................................... 2

5.2 Microwave-assisted digestion instruments ................................................................................................................... 2

5.3 Membrane filter, 0,45 µm pore size ....................................................................................................................................... 2

5.4 ICP-MS ............................................................................................................................................................................................................ 2

6 Preparation of standards solutions .................................................................................................................................................. 3

6.1 Diluted nitric acid, produced by mixing nitric acid (4.2) with pure water (4.1) at a

ratio of approximately 1+9 parts respectively. ............................................................................................................ 3

6.2 Diluting solution .................................................................................................................................................................................... 3

6.3 Internal Standard solutions. ........................................................................................................................................................ 3

6.3.1 Rhodium(*) standard solution, 1 mg/l ......................................................................................................... 3

6.3.2 Lutetium(*) standard solution, 1 mg/l ......................................................................................................... 3

6.4 Standard solutions ............................................................................................................................................................................... 4

6.4.1 High concentration mixed standard solution, 10 mg/l ................................................................... 4

6.4.2 Low concentration mixed standard solution, 0.1 mg/l .................................................................. 4

6.5 Calibration blank solution ............................................................................................................................................................. 4

6.6 Calibration solutions .......................................................................................................................................................................... 4

7 Procedure..................................................................................................................................................................................................................... 5

7.1 General ........................................................................................................................................................................................................... 5

7.2 Preparation of samples .................................................................................................................................................................... 5

7.3 Pressure assisted digestion .......................................................................................................................................................... 5

7.3.1 Preparation of Sample by Digestion – General case .......................................................................... 5

7.3.2 Preparation of Sample by Digestion – Specific cases ........................................................................ 6

7.3.3 Microwave digestion procedure ......................................................................................................................... 6

7.3.4 Preparation of measurement solutions ....................................................................................................... 6

7.4 Inductively Coupled Plasma Mass Spectrometry ...................................................................................................... 7

7.4.1 ICP-MS operating conditions ................................................................................................................................. 7

7.4.2 Quantification of the analytes by ICP-MS .................................................................................................... 7

7.5 Quality control of the analysis ................................................................................................................................................... 8

7.5.1 During the digestion ..................................................................................................................................................... 8

7.5.2 During the analysis ........................................................................................................................................................ 9

7.5.3 Example of ICP-MS sequence ................................................................................................................................ 9

8 Calculation ...............................................................................................................................................................................................................10

9 Method performance ....................................................................................................................................................................................10

Annex A Performance of the method determined by the accuracy profile methodology ........................12

Annex B (Informative) Information on the Evaluation of the method via ISO 5725 statistical

approach (*) ...........................................................................................................................................................................................................15

Bibliography .............................................................................................................................................................................................................................23

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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 217 Cosmetics.

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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Introduction

This standard specifies an analytical procedure for determination of trace elements (Chromium,

Cobalt, Nickel, Arsenic, Cadmium, Antimony and Lead) in finished cosmetics products by Inductively

Coupled Plasma Mass Spectrometry (ICP-MS) after pressure digestion of the sample. This type of

[1][2][3] [1][2][3]

analytical procedure is widely described in other areas such as environment, food and

[7][8][9][10]
pharmaceutical industry .
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oSIST prEN ISO 21392:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 21392:2020(E)
Cosmetics — Analytical methods — Measurement of traces
of heavy metals in cosmetic finished products using ICP/
MS technique
1 Scope

The aim of this standard is to provide a method of quantification of heavy metal trace elements in

cosmetic products that consumers might be exposed to in their usage. In the sample preparation

procedure, nitric acid/hydrochloric acid mixture is used and most of the cosmetic ingredients are

digested allowing heavy metal trace elements to be solubilized for measurement. Some cosmetic

inorganic ingredients such as silica or titanium dioxide might not be completely digested under the

conditions of this standard and heavy metal trace elements confined in such ingredients might not

be fully extracted. However, the heavy metal trace elements trapped in these inorganic materials

are considered less relevant for the evaluation of the exposure level of consumers to unwanted trace

elements. The use of ICP-MS ensures reliable measurement of trace elements due to its proven high

sensitivity and selectivity.

This analytical methodology can be applied to many other elements but this standard refers only to

the above listed trace elements and it is to the responsibility of the analyst to prove that it fits for

that purpose. In order to obtain comparable results, it is absolutely mandatory to comply with all the

conditions linked to the digestion of the samples.
2 Normative references
There is no normative reference in this document.
3 Principle

Trace elements in cosmetic products are quantified by ICP-MS measurement of the solutions resulting

from digestion of the cosmetic products. Digestion takes place with mineral acids in sealed vessels

heated to 200ºC by microwaves, producing high pressures.
4 Reagents

The reagents and the water used shall be free of the elements to be determined to such an extent

that the results are not impaired. Unless specified otherwise, solutions are understood to be aqueous

solutions.

4.1 Ultrapure water, conductivity below 0,1µS/cm-1 at 25°C according to Type 1 water specifications

[11]
defined in ISO 3696 standard
4.2 Nitric acid, minimum w = 60%, density = 1,38 g/ml
4.3 Hydrochloric acid, minimum w = 30 %, density = 1,15 g/ml
4.4 Internal standard stock solutions

For storage and stability conditions of the internal standard stock solutions, follow the specifications of

the suppliers.
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4.4.1 Rhodium stock solution, 1 000 mg/l
4.4.2 Lutetium stock solution, 1 000 mg/l

4.5 Analytes stock solutions (Chromium, Cobalt, Nickel, Arsenic, Cadmium, Antimony and Lead),

1 000 mg/l for each element

Commercially available single element or mixed stock solutions can be used. For this 2 cases, the used

stock solutions shall not contain other elements that could interfere with the analytes to be quantified.

4.6 Commercially available ICP-MS Tune solution, containing e.g. Ce, Co, Li, Mg, Tl and Y (1 µg/l)

according to instrument manufacturer’s recommendations.
5 Apparatus and equipment

All apparatus and equipment that come into direct contact with sample or solutions shall be pre-cleaned

with dilute nitric acid (6.1) and rinsed with ultrapure water (4.1) to ensure the lowest analyte background.

To prevent contamination and adsorption, do not use lab materials made with borosilicate glass.

5.1 Digestion vessels

Use commercially available, safety-tested pressure vessels and inserts made of acid-resistant, low-

contamination materials. The assembled vessels shall be able to safely withstand temperatures up to at

least 200°C and pressures up to at least 40 bar.

For determination of antimony, use only digestion containers with minimal surface roughness to

(6)[12],

prevent its adhesion to the container surface . Quartz containers are recommended because

they are usually more resistant to attrition. However, Teflon vessels without any scratch or damage on

their inner surface or any deposits are appropriate. Scratched or etched containers should not be used.

If there is any question regarding possible adsorption of antimony on vessels’ walls, test for surface

adsorption as described in section 7.3.3.

NOTE Dedicated digestion vessels are recommended for the digestion of cosmetic samples, which may have

high levels of elements to be determined. To avoid memory effects, perform a blank digestion to clean vessels

after digesting highly loaded samples, before digesting subsequent samples.
5.2 Microwave-assisted digestion instruments

Microwave-heated systems shall be equipped with a temperature measurement unit, which

simultaneously regulates the power control of the microwave. Reliable temperature measurement is

obtained e.g. through measurement sensors inserted into the pressure vessel. Only use microwave-

assisted digestion instruments equipped with temperature sensors and calibrate the temperature

sensor before use.
5.3 Membrane filter, 0,45 µm pore size

The membrane filter used shall be inert with regard to the acid concentration of the measurement

solution and shall not bring any contamination into the measurement solution or adsorption of the

analytes. Several types of membrane material are commercially available (PTFE, PP…) and their fit for

purpose must be verified by means of appropriate measurements (blanks, QC samples…).

5.4 ICP-MS

Mass spectrometer with inductively coupled argon plasma is composed of a sample introduction and

an atomisation system, as well as an instrument control and evaluation unit. To prevent interferences

with the masses of the elements of chromium, nickel, arsenic and cadmium, use of a mass spectrometer

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that is capable of compensating or minimising such interferences (e.g. collision and/or reaction cell,

resolution above 3000, alternatively corrective equations for higher concentrations).

6 Preparation of standards solutions

For all the solutions, the terminology “part” in the standard refers to either volume or weight. That

means that standards and samples can be diluted by volume or weight. However, it should be consistent

for both standards and samples.

6.1 Diluted nitric acid, produced by mixing nitric acid (4.2) with pure water (4.1) at a ratio

of approximately 1+9 parts respectively.
6.2 Diluting solution

The composition of the diluting solution must have the same acid composition (total content and acid

ratio) as the Analytical Solution (the diluted digest solution). This solution should contain:

— 2,5 part of nitric acid (4.2),
— 0,5 part of hydrochloric acid (4.3),
— 97 parts of water (4.1)
6.3 Internal Standard solutions.

The internal standards (IS) selected should cover all the mass range of the considered analytes and

have similar ionisation energy to the trace element for which it is used for correction purposes. It shall

also be checked that the native concentration of the internal standards in the sample to be analysed is

negligible and that they are not interfered by sample constituents.

“Rhodium and Lutetium have proved to be well suited as internal standards (IS). Samples should be

checked for negligible native concentrations of the IS and that the IS are not interfered with by sample

constituents.

Rhodium is suitable for determination of Chromium, Cobalt, Nickel, Arsenic, Cadmium and Antimony,

whereas Lutetium is suitable for determination of Lead. Alternatively, other elements may be used (for

example Indium or Iridium). Scandium, however, is not suitable as an IS due to Calcium interferences.

An IS with a mass (m/z) below 100 is not recommended because it may suffer from interferences from

matrix components.

NOTES : - Internal standard solutions may be added in each sample and calibration solution at the same

concentration or may be added through an on line Y-fitting to a pump tube.

- the concentration of the internal standard solutions must be included in the range 1 to 2 mg/l. In the following

sections, a concentration of 1 mg/l has been used for all the calculations.
6.3.1 Rhodium(*) standard solution, 1 mg/l

Dilute the Rhodium stock solution (4.4.1) 1 + 999 with diluting solution (6.2). This internal standard

solution is stable at room temperature for 6 months.
6.3.2 Lutetium(*) standard solution, 1 mg/l

Dilute the Lutetium stock solution (4.4.2) 1 + 999 with diluting solution (6.2). This internal standard

solution is stable at room temperature for 6 months.
(*) NOTE : Indium or Iridium may also be used as internal standards
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6.4 Standard solutions

The concentrations of these standard solutions are examples and shall be adjusted to the specific

conditions in the laboratories.
6.4.1 High concentration mixed standard solution, 10 mg/l
Dilute 100 times the analyte stock solution(s) (3.5) by adding:

— in the case of single analyte stock solutions, 1 part of each of these 7 solutions to 93 parts of the

diluting solution (6.2)

— in the case of mixed stock solution, add 1 part of this solution to 99 parts of the diluting solution (6.2).

This high standard solution is stable at room temperature for 6 months.
6.4.2 Low concentration mixed standard solution, 0.1 mg/l

Dilute 100 times the high concentration standard solution (5.4.1) by adding 1 part of this solution to

99 parts of the diluting solution (6.2). This low standard solution is stable at room temperature for

3 months.
6.5 Calibration blank solution

The calibration blank solution corresponds to the matrix solution without any analyte of interest.

Generally, it corresponds to the diluting solution with the suitable concentration of the appropriate

internal standards if not added via a Y-fitting during the measurement.
6.6 Calibration solutions

Mixed calibration solutions are prepared by diluting the low concentration mixed standard solution

(6.4.2) with the diluting solution (6.2) to levels in the linear range of the instrument and within the

targeted concentration range. Include a suitable concentration of the appropriate internal standards,

or add on line the internal standards by means of pumping into the sample flow through a Y-fitting.

At least 3 calibration solutions with various concentrations should be prepared. These calibration

solutions must be prepared daily.

Examples of preparation procedure of calibration solutions are detailed in Table 1a (with addition of

the internal standards in all the calibration solutions) and Table 1b (with on line addition of the internal

standards via an Y-fitting).

Table 1a — Example of calibration solutions of the ICP-MS – addition of the internal standards

in every calibration solution

Calibration solution Part of low Part of Rhodi- Part of Luteti- Part of the Analyte conc.

conc. mixed um standard um standard diluting solu- in the calibra-
standard solution solution tion tion solution
solution
(6.3.1) (6.3.2) (6.2) (µg/l)
(6.4.2)
5.5.0 Calibration blank 0 2 2 496 0
5.5.1 Calibration solution 1 2,5 2 2 493,5 0,5
5.5.2 Calibration solution 2 5 2 2 491 1
5.5.3 Calibration solution 3 10 2 2 486 2
5.5.4 Calibration solution 4 25 2 2 471 5
5.5.5 Calibration solution 5 50 2 2 446 10
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Table 1b — Example of calibration solutions of the ICP-MS – online addition of the internal

standards via an Y-fitting
Part of low Part of the di-
Analyte conc.
conc. mixed luting solution
in the calibra-
standard
Calibration solution
(6.2) tion solution
solution
(µg/l)
(6.4.2)
5.5.0 Calibration blank 0 500 0
5.5.1 Calibration solution 1 2,5 497,5 0,5
5.5.2 Calibration solution 2 5 495 1
5.5.3 Calibration solution 3 10 490 2
5.5.4 Calibration solution 4 25 475 5
5.5.5 Calibration solution 5 50 450 10
7 Procedure
7.1 General

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

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

is the responsibility of the user of this standard to take appropriate measures for ensuring the

safety and health of the personnel prior to application of the standard and to fulfil statutory

requirements for this purpose.
7.2 Preparation of samples

Homogenize the samples by means of suitable devices. After homogenization thoroughly clean the

devices in order to rule out contamination of the subsequent sample. The sample preparation step shall

ensure a homogeneous starting material for a weighed sample quantity.
7.3 Pressure assisted digestion

WARNING 1 Depending on the degree or reactivity of the sample, it may be required to weigh in lower

quantities than specified in Section 7.3.1 in order to prevent extreme reactions or explosions. It shall be taken

into account that digestion of samples with high carbon contents (e.g. carbohydrates, fats, oils, waxes) may cause

explosions. Alcohols or solvents in combination with concentrated nitric acid may cause delayed severe reactions

already at room temperature.Therefore it is highly recommended to gently evaporate all volatile components

before adding the acid (Section 7.3.2).

WARNING 2 Samples that are not covered by acid can cause local overheating of the digestion vessel and thus

lead to local melting and subsequent bursting of the digestion container. Prior to digestion, ensure that the entire

sample is fully covered by the acid mixture.

Temperature and pressure into the vessels must be carefully controlled to ensure a proper digestion

(section 5.2.). To avoid differences in temperature and pressure among vessels, one should only digest

samples with similar composition in the same microwave-assisted digestion batch.
7.3.1 Preparation of Sample by Digestion – General case
Precisely weigh ca. 200 mg of sample into a digestion container.

Add 1 ml of water (4.1) and thoroughly mix with a shaking device until the sample is completely

suspended in the water.

Add 5 ml nitric acid (4.2) to the mixture and mix again. The sample should be completely covered

with the solution. Allow the mixture to rest in a closed digestion vessel to ensure that the preliminary

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reaction takes place. Depending on the reactive behavior of the sample the duration of the preliminary

reaction can require resting periods of 30 minutes up to overnight.

Add then 1 ml of hydrochloric acid (4.3) and briefly mix. After addition of the hydrochloric acid, the

pressure vessel shall be closed and sealed immediately to make sure that the formed chlorine gas is

available for the reaction and does not evaporate.
7.3.2 Preparation of Sample by Digestion – Specific cases

• For highly water-based cosmetic products, such as lotion, milky lotion, cleanser, micellar water, a

sample mass could reach 400 mg. In this case no addition of water is required before addition of

acids (7.3.1).

• For all the other specific cases, sample mass can be adapted but the ratio between sample mass and

acid volumes (7.3.1) shall not be changed.

In case of high volatile content products, it is highly recommended for safety reason to completely

remove volatile portions through a caref
...

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