ISO/TS 21310:2025

Traditional Chinese medicine - Microscopic examination of medicinal herbs

This document specifies the methods for microscopic examination of medicinal herbs. It covers the equipment, sampling, preparation and observation methods. This document is applicable to medicinal herbs used in traditional Chinese medicine, including Chinese materia medica (whole medicinal materials) and decoction pieces derived from plants. It is not applicable to medicinal materials derived from animals or minerals.

Médecine traditionnelle chinoise — Examen microscopique des herbes médicinales

General Information

• Status: Published
• Publication Date: 17-Jun-2025
• ICS: 11.120.10 - Medicaments
• Technical Committee: ISO/TC 249 - Traditional Chinese medicine
• Drafting Committee: ISO/TC 249/WG 1 - Quality and safety of raw materials and traditional processing
• Current Stage: 6060 - International Standard published
• Start Date: 18-Jun-2025
• Due Date: 08-Dec-2025
• Completion Date: 18-Jun-2025

Relations

• Revises: ISO/TS 21310:2020 - Traditional Chinese medicine - Microscopic examination of medicinal herbs
• Effective Date: 15-Jun-2024

Overview

ISO/TS 21310:2025 - Traditional Chinese medicine - Microscopic examination of medicinal herbs is a Technical Specification from ISO/TC 249 that defines standardized methods for microscopic analysis of plant-derived medicinal herbs and decoction pieces used in traditional Chinese medicine (TCM). The document covers equipment, sampling, slide and powder preparation, mounting and swelling agents, observation procedures and test reporting. It applies to plant materials only (not animal or mineral materials) and updates the 2020 edition with revised sampling references and editorial improvements.

Key topics and technical requirements

• Scope and sampling
  • Sampling follows ISO 23723 (general requirements for herbal raw material and materia medica).
  • Representative samples should be preserved in airtight containers if needed.
• Apparatus
  • Optical microscope or slide scanner, optical/in-software micrometer, imaging devices (camera), slides and cover glasses, and botanical dissecting tools (tweezers, razor, microtome).
• Preparation methods
  • Cross- or longitudinal-section slides: soften, cut to typically 10–20 µm thickness, mount with mounting agent or chloral hydrate; paraffin embedding described when necessary.
  • Powder slides: about 1 mg sample, swollen with swelling agent/chloral hydrate for >10 min, smeared and mounted.
  • Mounting/swelling agents: examples include glycerine:water (1:1) or glycerine:95% ethanol:water (1:1:1); other suitable agents allowed.
• Fixation, maceration and sectioning
  • Fixatives: ethanol (50–70%), formalin (<5%), acetic acid, chromic acid (~1%), F.A.A. and Craf III formulations are provided.
  • Maceration methods: potassium hydroxide (5% KOH), chromic‑nitric acid, or potassium chlorate / dilute nitric acid techniques.
  • Sectioning: free‑hand thin sections, paraffin embedding with tert‑butanol (TBA) dehydration series, and frozen (cryosection) options; paraffin microtome thickness commonly 10–16 µm.
• Observation and reporting
  • Observation order: outer portion → inner portion → cell contents; for powder: characteristic components → abundant → rare → cell contents.
  • Test report must include sample identification, sampling method, reference to ISO/TS 21310:2025, results, optional operating details, anomalies and test date.

Applications and users

ISO/TS 21310:2025 is practical for:

• Quality control and authentication in TCM manufacturers and herbal medicine producers
• Pharmacognosy and academic research on medicinal herbs
• Regulatory and inspection laboratories validating raw materials and decoction pieces
• Herbal raw material suppliers, contract testing labs and pharmacopoeial committees

The standard supports consistent microscopic identification, contamination detection and component characterization-key activities for safety, traceability and regulatory compliance in herbal medicine supply chains.

Related standards

• ISO 23723 - Traditional Chinese medicine: general requirements for herbal raw material and materia medica (referenced for sampling)
• ISO 17639 and ISO 10934 (terminology sources cited in definitions)

Keywords: ISO/TS 21310:2025, microscopic examination, traditional Chinese medicine, medicinal herbs, slide preparation, powder slides, maceration, paraffin embedding, pharmacognosy, herbal quality control.

Standards Content (Sample)

Technical
Specification
ISO/TS 21310
Second edition
Traditional Chinese medicine —
2025-06
Microscopic examination of
medicinal herbs
Médecine traditionnelle chinoise — Examen microscopique des
herbes médicinales
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling . 2
5 Apparatus . 2
6 Preparation for microscopic examination . 2
6.1 Cross-section or longitudinal-section slides .2
6.2 Powder slides .2
6.3 Mounting and swelling agents .3
7 Observation of components . 3
8 Test report . 3
Annex A (informative) Preparation methods for microscopy. 4
Bibliography .10

iii
Foreword
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of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
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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 medicine, Subcommittee SC 1,
Traditional Chinese medicine.
This second edition cancels and replaces the first edition (ISO/TS 21310:2020), which has been technically
revised.
The main changes are as follows:
— the sampling method has been revised to refer to ISO 23723;
— improvements in sentence expressions and corrections of typographical errors.
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
Technical Specification ISO/TS 21310:2025(en)
Traditional Chinese medicine — Microscopic examination of
medicinal herbs
1 Scope
This document specifies the methods for microscopic examination of medicinal herbs. It covers the
equipment, sampling, preparation and observation methods. This document is applicable to medicinal herbs
used in traditional Chinese medicine, including Chinese materia medica (whole medicinal materials) and
decoction pieces derived from plants. It is not applicable to medicinal materials derived from animals or
minerals.
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 23723, Traditional Chinese medicine — General requirements for herbal raw material and materia medica
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
microscopic examination
examination of a test specimen by microscope with a magnification of generally ×50 to ×500
[SOURCE: ISO 17639:2022, 3.2, modified — “with or without etching” was removed from the definition.]
3.2
medicinal herbs
raw materials derived from various parts of plants for drugs used in herbal medicine
Note 1 to entry: Herbal medicine includes traditional Chinese medicine, Korean medicine and Kampo.
3.3
slide
flat rectangular plate of glass on which an object is mounted for microscopic examination
[SOURCE: ISO 10934:2020, 3.1.134, modified — Note 1 to entry was removed.]
3.4
cover glass
rectangular or circular piece of thin glass used to cover a microscopical preparation
[SOURCE: ISO 10934:2020, 3.1.34, modified — Note 1 to entry was removed.]

3.5
micrometer
device for measuring small lengths
[SOURCE: ISO 10934:2020, 3.1.96]
4 Sampling
The sampling method specified in ISO 23723 shall apply. After that, select a representative sample of the
material. If necessary, the samples should be preserved in airtight containers.
5 Apparatus
Use the usual laboratory apparatus and, in particular, the following.
5.1 Optical microscope or slide scanner.
5.2 Optical or in-software micrometer.
5.3 Imaging devices such as drawing attachments, embedded camera or digital imaging sensor for the
microscope.
5.4 Slides and cover glasses.
5.5 Botanical dissecting instruments such as tweezers, surgical knife, razor blade, microtome.
6 Preparation for microscopic examination
6.1 Cross-section or longitudinal-section slides
a) According to the sample condition, moisturizing, fixation or maceration process can be added. See
Clauses A.1 to A.3 for additional information.
b) Select representative pieces of the material being examined and cut into suitable lengths.
c) After softening, cut the material with a razor blade or a microtome to a thickness of 10 μm to 20 μm
generally.
d) Place a section on a slide glass, add two or three drops of a mounting agent or chloral hydrate solution
and place a cover glass over it, taking precautions against the inclusion of bubbles.
e) Embed the material in hard paraffin for cutting, if necessary. See Clause A.4.
6.2 Powder slides
a) Place approximately 1 mg of powdered sample in a watch glass containing two or three drops of a
swelling agent or chloral hydrate solution, stir well with a small rod to prevent the inclusion of bubbles
and allow to stand for more than 10 min to swell the sample.
b) Using a small glass rod, smear the slide glass with a small amount of the swollen sample, add one drop
of the mounting agent and place a cover glass on it so that the tissue sections spread evenly without
overlap, taking precautions against the inclusion of bubbles.

6.3 Mounting and swelling agents
Mounting and swelling agents may be made of a mixture of glycerine and water (1:1) or a mixture of
glycerine, 95 % ethanol and water (1:1:1). Other agents which have characteristics of mounting and swelling
agents can be used.
7 Observation of components
Observation can be conducted in the order of the outer portion, inner portion and cell contents. In case of a
powdered sample, observation can be made in the order of characteristic component, matter present in large
amounts, rarely existing matter and cell contents. For histochemical detection of the sample, see Clause A.6.
8 Test report
The test report shall include the following information:
a) all information necessary for the complete identification of the sample;
b) the sampling method used;
c) the test method used, with reference to this document, i.e. ISO/TS 21310:2025;
d) the test result(s) obtained;
e) all operating details not specified in this document, or regarded as optional, together with details of any
incidents which can have influenced the test result(s);
f) any unusual features (anomalies) observed during the test;
g) the date of the test.
Annex A
(informative)
Preparation methods for microscopy
A.1 Moisturizing
Dried parts of a plant can require softening before preparation for microscopy, preferably by soaking in
water. Use a desiccator for larger quantities of material, placing water into the lower part instead of the
drying agent.
Bark, wood and other dense and hard materials should be soaked in water or in equal parts of water, ethanol
and glycerol for a few hours or overnight until they are soft enough to be cut. Boiling in water for a few
minutes can sometimes be necessary.
Any water-soluble contents can be removed from the cells by soaking in water. Starch gr
...