ISO/TS 21310:2020

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: 14-Jul-2020
• 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: 9599 - Withdrawal of International Standard
• Start Date: 18-Jun-2025
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO/TS 21310:2025 - Traditional Chinese medicine - Microscopic examination of medicinal herbs
• Effective Date: 15-Jun-2024

Overview

ISO/TS 21310:2020 - Traditional Chinese medicine - Microscopic examination of medicinal herbs - specifies standardized methods for the microscopic analysis of plant-derived medicinal materials used in traditional Chinese medicine (TCM). The technical specification describes required equipment, sampling amounts, sample preparation (sections and powders), mounting/swelling agents, observation procedures and reporting. It applies to Chinese materia medica (whole medicinal materials) and decoction pieces derived from plants, but excludes animal- or mineral-derived materials.

Key topics and technical requirements

• Scope and definitions: Clarifies terms such as microscopic examination, slide, cover glass and micrometer; prepared in line with ISO/TC 249 terminology.
• Sampling: Guidance on representative sample sizes - small/powdered (50–250 g) and large/whole (250–500 g) - and preservation in airtight containers when needed.
• Apparatus: Use of optical microscopes or slide scanners, micrometers (optical or software), imaging devices (digital cameras), slides, cover glasses and botanical dissecting tools (tweezers, microtome, razor).
• Preparation methods:
  • Cross-section and longitudinal-section slides (cutting to 10–20 µm; optional paraffin embedding).
  • Powder slides (swelling in agents for ≥10 minutes and uniform smearing).
  • Mounting and swelling agents (e.g., glycerine/water 1:1 or glycerine/95% ethanol/water 1:1:1).
  • Annex A contains informative methods: moisturizing, fixation (ethanol, formalin, F.A.A., Craf III), maceration (KOH, chromic‑nitric, potassium chlorate), sectioning (free-hand, paraffin embedding, frozen/cryosection) and staining.
• Observation: Recommended observation order for whole and powdered samples (outer/inner portions, characteristic components, cell contents); includes histochemical detection procedures (e.g., phloroglucinol test for lignified walls).
• Test report requirements: Must include sample identification, sampling method, reference to ISO/TS 21310:2020, test methods and results, optional operating details, anomalies and test date.

Applications and intended users

• Quality control laboratories in herbal medicine manufacturers and suppliers
• Regulatory and pharmacopoeial testing bodies evaluating botanical identity and purity
• Research laboratories conducting anatomical and histochemical studies of medicinal herbs
• Educational institutions teaching pharmacognosy and TCM materia medica

ISO/TS 21310:2020 helps ensure consistent, reproducible microscopic identification of plant-based TCM materials, supporting authenticity checks, adulteration detection and quality assurance.

Related standards

• ISO/TC 249 (Traditional Chinese medicine) - responsible technical committee
• Cited terminology sources: ISO 17639:2003 and ISO 10934-1:2002 (for microscopy terms)

Keywords: ISO/TS 21310:2020, traditional Chinese medicine, microscopic examination, medicinal herbs, Chinese materia medica, decoction pieces, sample preparation, microscopy, microtome, paraffin embedding, powder slides, histochemical detection.

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 21310
First edition
2020-07
Traditional Chinese medicine —
Microscopic examination of
medicinal herbs
Médecine traditionnelle chinoise — Examen microscopique des herbes
médicinales
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2020 – All rights reserved

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 . 2
7 Observation of components . 3
8 Test report . 3
Annex A (informative) Preparation methods for microscopy . 4
Bibliography .10
Foreword
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iv © ISO 2020 – All rights reserved

TECHNICAL SPECIFICATION ISO/TS 21310:2020(E)
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
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
microscopic examination
examination of a test specimen by microscope with a magnification of generally × 50 to × 500
[SOURCE: ISO 17639:2003, 3.2, modified.]
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 10934-1:2002, 2.133]
3.4
cover glass
rectangular or circular piece of thin glass used to cover a microscopical preparation
[SOURCE: ISO 10934-1:2002, 2.34, modified — Note 1 to entry removed.]
3.5
micrometer
device for measuring small lengths
[SOURCE: ISO 10934-1:2002, 2.96]
4 Sampling
Small-sized, cut or powdered material (50 g to 250 g) samples shall be taken after mixing thoroughly.
Large-sized or whole material (250 g to 500 g) samples shall be taken after mixing thoroughly. 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
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.
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 A.4.
6.2 Powder slides
a) Place about 0,1 g 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) as mounting and swelling agents. Other agents which have
characteristics of mounting and swelling agents can be used.
2 © ISO 2020 – All rights reserved

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 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 21310:2020;
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 may 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 may 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 need to 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 grains can
be gelatinized by heating in water. In certain cases, material can be moistened with water for a few
minutes to soften the surfaces and allow sections to be cut.
A.2 Fixation
Fixation is the process of preserving the tissue by placing the tissue in fixatives. The permeation of
fixatives into the tissue can be dependent upon the size of the sample. Before fixation, it is recommended
that samples be cut smaller than 6 mm ⨯ 6 mm ⨯ 6 mm.
The following water solutions are used as fixatives:
— ethanol: 50 % to 70 %
—
...