ISO 19842:2025

Traditional Chinese medicine - Dioscorea opposita rhizome

This document specifies the quality and safety requirements and test methods of Dioscorea opposita rhizome (dried rhizome of Dioscorea opposita Thunb.). It is applicable to Dioscorea opposita rhizomes that are sold and used as natural medicines in international trade, including Chinese materia medica (whole medicinal material) and decoction pieces derived from this plant.

Médecine traditionnelle chinoise — Rhizome de Dioscorea opposita

General Information

• Status: Published
• Publication Date: 08-May-2025
• ICS: 11.120.10 - Medicaments
• Technical Committee: ISO/TC 249 - Traditional Chinese medicine
• Drafting Committee: ISO/TC 249 - Traditional Chinese medicine
• Current Stage: 6060 - International Standard published
• Start Date: 09-May-2025
• Due Date: 15-Mar-2026
• Completion Date: 09-May-2025

Overview

ISO 19842:2025 - Traditional Chinese medicine - Dioscorea opposita rhizome establishes internationally harmonized quality and safety requirements and test methods for the dried rhizome of Dioscorea opposita Thunb. (also used as Chinese materia medica and decoction pieces). The standard applies to rhizomes sold and used as natural medicines in international trade and supports consistent product quality, safety and regulatory compliance across markets.

Key topics and technical requirements

• General requirements: material must be clean, free from leaves, visible contaminants, mould or live insects before sampling.
• Morphology & microscopy: macroscopic description (15–30 cm length; 1.5–6 cm diameter; yellowish-white surface, powdery white section) and microscopic features (starch granules 8–35 μm, vessels 12–48 μm, calcium oxalate needle bundles ≈240 μm).
• Limits:
  • Moisture: mass fraction ≤ 16.0 %.
  • Total ash: mass fraction ≤ 6.0 %.
  • Water‑soluble extractives: to be determined (method specified).
• Contaminants & residues:
  • Heavy metals: determination of arsenic, mercury, lead and cadmium.
  • Pesticide residues: determination per specified methods.
  • Sulfur dioxide: determination required.
• Identity testing: Thin-layer chromatography (TLC) identification - extract must show spot/band matching reference solution in color and Rf. (Annex A provides TLC details.)
• Sampling & test methods: sampling follows ISO 23723; macroscopic ID samples not less than 500 g; test methods reference several ISO standards for microscopy, heavy metals, pesticides, sulfur dioxide and other measures.
• Packaging, storage & transport: requirements to protect material from light, moisture and contamination; storage and packaging reference ISO 22217 and ISO 23723.

Practical applications and who uses this standard

ISO 19842:2025 is intended for:

• Manufacturers and processors of Dioscorea opposita rhizome and decoction pieces - for quality control and product specification.
• Testing laboratories and QC analysts - for validated sampling and test procedures (TLC, moisture, ash, contaminants).
• Regulatory authorities and customs - to assess imported/exported TCM raw materials against harmonized safety limits.
• Suppliers, exporters/importers and purchasers - to ensure consistent international trade quality.
• Pharmacopeial bodies and standards developers - to align national regulations with an international baseline.

Related standards

Key referenced ISO documents include: ISO 23723, ISO/TS 21310, ISO 18664, ISO 22258, ISO 22590, ISO 22217, and ISO 21371 - covering sampling, microscopy, heavy metals, pesticide residues, sulfur dioxide, storage and labelling.

Standards Content (Sample)

International
Standard
ISO 19842
First edition
Traditional Chinese medicine —
2025-05
Dioscorea opposita rhizome
Médecine traditionnelle Chinoise — Rhizome de Dioscorea
opposita
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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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Descriptions . 1
5 Quality and safety requirements and recommendations . 2
5.1 General characteristics .2
5.2 Morphological features .2
5.3 Microscopic characteristics .2
5.4 Moisture .3
5.5 Total ash .3
5.6 Water-soluble extractives .3
5.7 Thin-layer chromatogram (TLC) identification .3
5.8 Heavy metals .3
5.9 Pesticide residues .3
5.10 Sulfur dioxide . .4
6 Sampling . 4
7 Test methods . 4
7.1 Macroscopic identification .4
7.2 Microscopic identification .4
7.3 Determination of moisture .4
7.4 Determination of total ash .4
7.5 Determination of water-soluble extractives .4
7.6 Thin-layer chromatogram (TLC) identification .4
7.7 Determination of heavy metals .4
7.8 Determination of pesticide residues .4
7.9 Determination of sulfur dioxide .4
8 Test report . 4
9 Packaging, storage and transportation . 5
10 Marking and labelling . 5
Annex A (informative) Thin-layer chromatogram (TLC) identification . 6
Annex B (informative) Referenced values of national and regional limits for Dioscorea opposita
rhizome . 8
Bibliography .10

iii
Foreword
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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.

iv
Introduction
Dioscorea opposita rhizome is the dried rhizome of Dioscorea opposita Thunb. It has a long history of
application as a traditional Chinese herb in China, the Republic of Korea, Japan, etc. It is widely used clinically
for its efficacy in nourishing the spleen and stomach, generating body fluid and benefiting the lungs, and
tonifying the kidneys and acting as an astringent essence. Dioscorea opposita rhizome is mostly processed
into Dioscorea opposita rhizome decoction pieces, bran-fried Dioscorea opposita rhizome and other products
circulating in the market. Dioscorea opposita rhizome has a long history of cultivation and is grown all over
the world. In 2020, the global Dioscorea opposita rhizome cultivation area is about 9,205 million hectares and
Dioscorea opposita rhizome production is about 76,031 million tonnes, both of which are on a growing trend.
To date, Dioscorea opposita rhizome has been widely recorded in established pharmacopoeias such
as the Chinese Pharmacopoeia, Korean Pharmacopoeia, Japanese Pharmacopoeia, and the European
Pharmacopoeia. But different quality requirements in different countries and regions, different packaging,
transportation and storage conditions can affect the quality of Dioscorea opposita rhizome. Meanwhile,
Dioscorea opposita rhizome occupies the No. 65 place on the priority list of ISO/TR 23975. Therefore, it is
urgent and necessary to establish a unified international standard for Dioscorea opposita rhizome to ensure
its quality and safety.
As national implementation can differ, national standards bodies are invited to modify the values given in
5.4 and 5.5 in their national standards. Examples of national and regional values are given in Annex B.

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International Standard ISO 19842:2025(en)
Traditiona
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