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.