FprEN ISO 23821

Cosmetics - Analytical methods - Determination of traces of mercury in cosmetics by atomic absorbtion spectrometry (AAS) cold vapour technology after pressure digestion (ISO/FDIS 23821:2022)

This document specifies a method for determination of mercury in cosmetics by means of cold vapour atomic absorption spectrometry (AAS) with a prior pressure digestion.

Kosmetische Mittel - Untersuchungsverfahren - Bestimmung von Quecksilberspuren in kosmetischen Mitteln durch Atomabsorptionsspektrometrie (AAS) Kaltdampftechnologie nach Druckaufschluss (ISO/FDIS 23821:2022)

Dieses Dokument legt ein Verfahren zur Bestimmung von Quecksilber in kosmetischen Mitteln mittels Kaltdampf-Atomabsorptionsspektrometrie (AAS) nach Druckaufschluss fest.

Cosmétiques - Méthodes d’analyse - Dosage des traces de mercure dans les cosmétiques par la technique de spectrométrie d’absorption atomique (SAA) de vapeur froide après digestion sous pression (ISO/FDIS 23821:2022)

Le présent document spécifie une méthode de dosage du mercure dans les cosmétiques par spectrométrie d'absorption atomique (SAA) de vapeur froide après digestion sous pression.

Kozmetika - Analizne metode - Določevanje živega srebra v sledovih v kozmetičnih izdelkih z atomsko absorpcijsko spektrometrijo (AAS) s tehniko hladnih par po razklopu pod tlakom (ISO/FDIS 23821:2022)

General Information

• Status: Not Published
• ICS: 71.100.70 - Cosmetics. Toiletries
• Technical Committee: CEN/TC 392 - Cosmetics
• Drafting Committee: CEN/TC 392/WG 1 - Analytical methods
• Current Stage: 6055 - CEN Ratification completed (DOR) - Publishing
• Due Date: 02-Sep-2021
• Ref Project: kSIST FprEN ISO 23821:2022 - Cosmetics - Analytical methods - Determination of traces of mercury in cosmetics by atomic absorbtion spectrometry (AAS) cold vapour technology after pressure digestion (ISO/FDIS 23821:2022)

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 23821:2021
01-marec-2021
Kozmetika - Analizne metode - Določevanje živega srebra v kozmetičnih izdelkih z
atomsko absorpcijsko spektrometrijo (AAS) s tehniko hladnih par po razklopu pod
tlakom (ISO/DIS 23821:2021)

Cosmetics - Analytical methods - Determination of traces of mercury in cosmetics by

atomic absorbtion spectrometry (AAS) cold vapour technology after pressure digestion

(ISO/DIS 23821:2021)

Kosmetische Mittel - Untersuchungsverfahren - Bestimmung von Quecksilberspuren in

kosmetischen Mitteln durch Atomabsorptionsspektrometrie (AAS) Kaltdampftechnologie

nach Druckaufschluss (ISO/DIS 23821:2021)
Cosmétiques - Méthodes d’analyse - Dosage des traces de mercure dans les

cosmétiques par la technique de spectrométrie d’absorption atomique (SAA) de vapeur

froide après digestion sous pression (ISO/DIS 23821:2021)
Ta slovenski standard je istoveten z: prEN ISO 23821
ICS:
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
71.100.70 Kozmetika. Toaletni Cosmetics. Toiletries
pripomočki
oSIST prEN ISO 23821:2021 en,fr,de

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

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oSIST prEN ISO 23821:2021
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oSIST prEN ISO 23821:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 23821
ISO/TC 217 Secretariat: ISIRI
Voting begins on: Voting terminates on:
2021-02-04 2021-04-29
Cosmetics — Analytical methods — Determination of
traces of mercury in cosmetics by atomic absorbtion
spectrometry (AAS) cold vapour technology after pressure
digestion
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 23821:2021(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 2021
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oSIST prEN ISO 23821:2021
ISO/DIS 23821:2021(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
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Phone: [phone]
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Published in Switzerland
ii © ISO 2021 – All rights reserved
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oSIST prEN ISO 23821:2021
ISO/DIS 23821:2021(E)
Contents Page

European foreword .............................................................................................................................................................................................................iv

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

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

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

4 Reagents ........................................................................................................................................................................................................................ 2

5 Apparatus and equipment .......................................................................................................................................................................... 3

6 Procedure..................................................................................................................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Preparation of samples .................................................................................................................................................................... 4

6.3 Pressure assisted digestion .......................................................................................................................................................... 4

6.3.1 Preparation of sample by digestion – General case ........................................................................... 4

6.3.2 Preparation of sample by digestion – Specific cases ......................................................................... 4

6.3.3 Microwave digestion procedure ......................................................................................................................... 5

6.3.4 Preparation of measurement solutions ....................................................................................................... 5

6.4 Atomic absorption spectrometry (cold vapour AAS) ............................................................................................ 5

6.4.1 Spectrometry settings ................................................................................................................................................. 5

6.4.2 Example for AAS determination using cold vapour technology ............................................. 6

6.5 Quality control of the analysis ................................................................................................................................................... 6

7 Evaluation .................................................................................................................................................................................................................... 6

7.1 Calculation .................................................................................................................................................................................................. 6

7.2 Determination limit ............................................................................................................................................................................ 7

7.3 Reliability of the method ................................................................................................................................................................ 7

8 Test report ................................................................................................................................................................................................................... 7

9 Alternative stabilizing reagents............................................................................................................................................................ 7

10 Short-t erm stabilization when measuring with potassium permanganate solution ....................8

Annex A (normative) Performance of the method determined via ISO 5725 statistical approach.....9

Annex B (normative) ISO 23674 and ISO 23821 common interlaboratory test results ...............................12

Bibliography .............................................................................................................................................................................................................................14

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oSIST prEN ISO 23821:2021
ISO/DIS 23821:2021(E)
European foreword

This document (prEN 23821:2020) has been prepared by Technical Committee CEN/TC 392 “Cosmetics”,

the secretariat of which is held by AFNOR.
This document is a working document.
iv © ISO 2021 – All rights reserved
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oSIST prEN ISO 23821:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 23821:2021(E)
Cosmetics — Analytical methods — Determination of
traces of mercury in cosmetics by atomic absorbtion
spectrometry (AAS) cold vapour technology after pressure
digestion
1 Scope

This European standard specifies a process for determination of mercury in cosmetics by means of

cold vapour atomic absorption (AAS) with a prior pressure digestion. This process was validated by

means of an interlaboratory test according to ISO 5725-2 [6] using e.g. lipstick, body lotion, toothpaste

and eyeshadow, with a mercury concentration in the range of 0,110 mg/kg to 5,84 mg/kg. Statistical

characteristics regarding this interlaboratory test are provided in Annex A, Table A.1.

This standard has been developed in parallel with ISO 23674. Knowing this, an interlaboratory test

using either one or the other method was performed on same tailor-made cosmetic products in order to

establish that both methods fulfilled the same requirements (see Annex B).
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

ISO 23674, Cosmetics — Analytical Methods — Determination of mercury in cosmetics by integrated

mercury analytical systems
3 Principle

As a first step, the finished cosmetic product is digested in a closed container at high temperatures and

pressure using mineral acids. Pressure digestion is carried out at a temperature of 200 °C obtained by

means of microwave-assisted heating.

After digestion of the cosmetics the concentration of mercury is determined by quantification using the

AAS cold vapour technology.

During mineralisation of the sample it is not possible to dissolve all cosmetics without residues,

depending on their type and composition. In order to obtain comparable results, it is absolutely

mandatory to comply with the conditions specified for this process.

The measurement solution is transferred to the reaction container of the mercury analysis unit. From

there, mercury is rinsed out into the cuvette of the AAS instrument with the help of a carrier gas flow

after reduction with divalent tin or sodium borohydride. Absorption at the mercury line of 253,7 nm is

used as a measure for mercury concentration in the cuvette. By using a gold/platinum mesh (amalgam

technology) for concentration of the rinsed-off mercury prior to measurement in the cuvette it is

possible to achieve lower LOQs.
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oSIST prEN ISO 23821:2021
ISO/DIS 23821:2021(E)
4 Reagents

The reagents and the water used shall be free of mercury to such an extent that the analysis is not

impaired. Unless specified otherwise, pure-analysis chemicals shall be used and solutions are

understood to be aqueous solutions. Use water conforming to Grade 1 of ISO 3696 (conductivity below

0,1 µS/cm at 25 °C).
4.1 Hydrochloric acid, minimum w = 30 %, density = 1,15 g/ml.
4.2 Nitric acid, minimum w = 65 %, density = 1,4 g/ml.

4.3 Diluted nitric acid, produced by mixing nitric acid (4.2) with water at a ratio of approximately

1 + 9 parts respectively.
4.4 Reducing agents, for example tin(II) chloride or sodium borohydride.

Alternating operation with both reducing agents (4.4.1 and 4.4.2) is not recommended. For this purpose,

the appropriate information from the manufacturer of the instrument shall be followed.

The mass concentrations of the reducing agent solutions can vary, depending on the system. The

corresponding data of the manufacturer of the instrument shall be complied with.
4.4.1 Tin(ll) chloride solution, for example mass concentration ρ = 100 g/l.

Weigh 50 g tin(ll) chloride, SnCI ·2H 0 in a 500 ml volumetric flask and dissolve in approximately

2 2

100 ml hydrochloric acid (4.1) and dilute to the mark with water. The solution shall be freshly prepared

prior to use.
4.4.2 Sodium borohydride solution, for example ρ = 30 g/l.

Dissolve 3 g of sodium borohydride and 1 g of sodium hydroxide pellets in water and dilute with 100 ml

water. The solution shall be freshly prepared every day and filtered prior to use.

WARNING — Compliance with the safety instructions is mandatory when working with sodium

borohydride. Sodium borohydride forms acids when combined with hydrogen, which can result

in an explosive air/hydrogen mixture. A fixed exhaust system shall be installed/present in the

area where measurements are carried out.
4.5 Stabilization

The standard, calibration and sample digestion solutions are stabilized with hydrochloric acid (4.1). It

is recommended to set a hydrochloric acid concentration of around ω = 1% in the solutions. Alternative

stabilizing reagents can also be used (see Clause 9).
4.6 Mercury stock solution, mercury mass concentration of ρ = 1 000 mg/l.

The stock solution is commercially available. It is recommended to use certified stock solutions. As

an alternative, the stock solution prepared from mercury(II) oxide can be stabilised using potassium

[1] [3]

dichromate or solution prepared from mercury(II) chloride can be stabilised using nitric acid (4.2) .

4.7 Mercury standard solutions

Dilute the stock solutions to the concentrations required for calibration and add the necessary amount

of stabilisation reagent (4.6), In doing so, select concentrations that the linear range of the reference

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oSIST prEN ISO 23821:2021
ISO/DIS 23821:2021(E)

function is not exceeded. It is recommended to use at least 3 standard solutions with different

concentrations.

The acid concentration in the standard solution shall correspond to the acid concentration of the

measurement solution. Mercury standard solutions have a rather short shelf life, even at higher

concentrations; therefore, they shall be freshly prepared every day.
4.8 calibration blank solution

The calibration blank solution shall contain water, the same amount of stabilisation reactant as the

mercury standard solutions (4.7) per litre and the quantities of nitric acid (4.2) and hydrochloric acid

(4.1) that correspond to the acid concentrations in the measurement solution.
5 Apparatus and equipment

For the determination of mercury all apparatus and equipment that come into direct contact with the

sample and the solutions used shall be thoroughly pre-treated to ensure minimisation of contamination.

The following steps are recommended for cleaning: Rinse with drinking water, treat with a scouring

agent solution, repeat rinsing with drinking water and soak in diluted nitric acid (4.3) over night or a

prolonged period. Prior to use, rinse the apparatus with ultrapure water and dry. Steaming of chemically

inert vessels and containers (e.g. made of quartz glass) using nitric acid (4.2) is an effective cleaning

method and is regularly used in element trace analysis. 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 resist and, 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.

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 sequent 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, pore size: 0,45 µm.

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 (e.g. PTFE, PP) and their fit

for purpose shall be verified by means of appropriate measurements (e.g. blanks, QC samples).

5.4 Atomic absorption spectrometer, optionally available with background compensation function

and including accessories for cold vapour technology or amalgam technology.
Flow injection systems can be used as an alternative of manual processes.
5.5 Element-specific light for mercury
Measurement at 253,7 nm.
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oSIST prEN ISO 23821:2021
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6 Procedure
6.1 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.

During all process steps it shall be ensured that there are no losses of analyte and that contamination is

kept as low as possible.
6.2 Preparation of samples

Before the digestion of the sample a suitable preparation needs to be carried out (e.g. homogenizing,

[13]

mixing, crushing ). 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.
6.3 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 6.3.1 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 6.3.2).

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 inside the vessels shall be carefully controlled to ensure a proper digestion.

To avoid differences in temperature and pressure among vessels, one should only digest samples with

similar composition in the same microwave-assisted digestion batch.
6.3.1 Preparation of sample by digestion – General case
Precisely weigh about 200 mg of sample into a digestion container.

Add 1 ml of water 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

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

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

Then add 1 ml of hydrochloric acid (4.1) 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.
6.3.2 Pr
...