ISO 22590:2020

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 22590
ISO/TC 249
Traditional Chinese medicine —
Secretariat: SAC
Determination of sulfur dioxide in
Voting begins on:
2020­06­01 natural products by titration
Voting terminates on:
Médecine traditionnelle chinoise — Dosage du dioxyde de soufre dans
2020­07­27
les produits naturels par titrage
RECIPIENTS OF THIS DRAFT ARE INVITED TO
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OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 22590:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

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ISO/FDIS 22590:2020(E)

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© ISO 2020
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ii © ISO 2020 – All rights reserved

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ISO/FDIS 22590:2020(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus . 2
5 Reagents . 2
6 Sampling and preservation of samples . 2
6.1 Sampling . 2
6.1.1 Laboratory samples . 2
6.1.2 Sample identification . 2
6.2 Sample pre­treatment and preservation . 3
6.2.1 Sample pre­treatment . 3
6.2.2 Sample storage . 3
7 Test method . 3
7.1 Test procedure . 3
7.2 Calculation . 4
Annex A (informative) Reference of national, regional and organizational limits of
sulfur dioxide in food and natural products of traditional Chinese medicine and
calculated limits using target hazard quotients based on USEPA and WHO .6
Annex B (informative) Gas chromatography — Determination of sulfur dioxide in natural
traditional Chinese medicine materials . 9
Annex C (informative) Analysis of the similarities and differences of acid-base titration
in different countries .10
Bibliography .13
© ISO 2020 – All rights reserved iii

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ISO/FDIS 22590:2020(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 non­governmental, 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 249, Traditional Chinese medicine.
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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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 22590:2020(E)
Traditional Chinese medicine — Determination of sulfur
dioxide in natural products by titration
1 Scope
This document specifies the determination method of sulfur dioxide in natural products used in
traditional Chinese medicine, which includes the requirements of the device, chemicals, operational
procedures and formula.
It is applicable to natural products of traditional Chinese medicine, including Chinese materia medica
(whole medicinal materials) and decoction pieces derived from plants or animals.
It is not applicable to minerals used in traditional Chinese medicine.
2 Normative references
There are no normative references in this document.
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
sulfur dioxide
toxic gas with a pungent, irritating smell, the chemical compound with the formula SO
2
3.2
sulfur dioxide residue
sulfur dioxide that remains in or on a natural product
Note 1 to entry: Sulfur dioxide residue is expressed as mg/kg.
3.3
maximum residue limit
MRL
highest level of sulfur dioxide that is permitted in or on a natural product
Note 1 to entry: Maximum residue limit is expressed as mg/kg.
3.4
acceptable daily intake
ADI
estimate of the amount of sulfur dioxide in natural products that can be safely consumed daily over a
lifetime without adverse health effects
Note 1 to entry: ADI is expressed in milligrams of the sulfur dioxide, as it appears in the natural products, per
kilograms of body mass per day (mg/kg/day).
© ISO 2020 – All rights reserved 1

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ISO/FDIS 22590:2020(E)

3.5
acid-base titration
determination of the concentration of an acid or base by exactly neutralizing the acid or base with a
base or acid of known concentration
4 Apparatus
4.1 Glass sample, cleaned thoroughly before use.
4.2 Electronic balance, with a minimum reading of 0,1 mg.
4.3 Separatory funnel, with a capacity of 50 ml or 100 ml.
4.4 Round-bottom flask, with a capacity of 500 ml or 1 000 ml.
5 Reagents
All reagents shall be of recognized chromatographic or analytical purity. Distilled water or water of
equivalent purity or above, recently boiled, shall be used.
5.1 Distilled water.
5.2 Bromophenol blue, 1 g/l solution of bromophenol blue in ethanol (20 % volume fraction).
5.3 Hydrochloric acid, 6 mol/l solution of diluted hydrochloric acid. Dilute one volume of concentrated
hydrochloric acid.
5.4 Hydrogen peroxide, 3 % volume fraction solution of diluted hydrogen peroxide, free from
sulfate ions.
5.5 Sodium hydroxide, 0,1 mol/l solution of sodium hydroxide (standard volumetric solution).
6 Sampling and preservation of samples
6.1 Sampling
6.1.1 Laboratory samples
Raw material samples received by the laboratory shall be accompanied with complete information such
as the source and time of collection of the samples. The samples for testing can include Chinese materia
medica (whole medicinal materials) and decoction pieces derived from plants or animals.
6.1.2 Sample identification
When a sample is received, it shall be immediately assigned a unique label which will accompany it
through all stages of the analysis to the reporting of the results. Samples shall be subject to the
appropriate disposal review system and all records shall be accurately kept.
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ISO/FDIS 22590:2020(E)

6.2 Sample pre-treatment and preservation
6.2.1 Sample pre-treatment
Before testing, the sample shall be dried and powdered. Samples shall be pre­treated as soon as possible
and stored in a cool and dry place – if possible, in a refrigerator.
6.2.2 Sample storage
If samples cannot be analysed immediately, they shall be stored in a cool and dry place, away from the
direct sunlight, and analysed within a few days.
7 Test method
7.1 Test procedure
a) Introduce 150 ml of water into the flask (see Figure 1, key 1), open the condenser pipe (key 3) and
pass carbon dioxide through the whole system for 15 min at a rate of 100 ± 5 ml/min. To 10 ml of
diluted hydrogen peroxide solution add 0,15 ml of a 1 g/l solution of bromophenol blue in ethanol
(20 % volume fraction).
b) Add 0,1 M sodium hydroxide until a violet-blue colour is
...