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.