ISO 22258:2020

Overview

ISO 22258:2020 - Traditional Chinese medicine - Determination of pesticide residues in natural products by gas chromatography (GC) - specifies a harmonized laboratory method for detecting and quantifying pesticide residues in plant-derived materials used in Traditional Chinese Medicine (TCM). It covers Chinese materia medica (whole medicinal materials) and decoction pieces, and provides method guidance (Annex A) plus reference maximum and recommended limits (Annexes B and C) based on pharmacopoeias and international guidance.

Key topics and technical requirements

• Scope and applicability: Analytical method by gas chromatography (GC) for pesticide residues in TCM plant materials.
• Sampling: Samples must be representative of the batch and accompanied by traceability information (name, source, specification).
• Reagents and contamination control: Use chromatographic-grade reagents; verify reagent purity with blank chromatograms to avoid interfering peaks.
• Apparatus and cleaning: Thorough glassware cleaning (soak ≥16 h in phosphate-free detergent, rinse, wash with acetone then hexane/heptane). Avoid PVC; use PP, PTFE or nylon where needed.
• Extraction and purification (Annex A):
  • Extraction example: acetone extraction with toluene concentration; use cartridge/size‑exclusion cleanup.
  • Purification: size‑exclusion chromatography (styrene‑divinylbenzene packing) and silica gel column cleanup for organochlorine, organophosphorus and pyrethroids.
• GC analysis parameters (Annex A excerpt):
  • Example column: fused silica 0.32 mm × 30 m, 0.25 μm dimethylpolysiloxane film.
  • Detectors: AFID or FPD; specified temperature program and injection/detector temperatures.
• Validation criteria:
  • Recovery: generally 70–120% (lower allowed with justification).
  • Precision: repeatability and reproducibility expressed as RSD in specified concentration ranges (see Table 1).
• Limits calculation:
  • Limit (mg/kg) = A·m / (100·B), where A = ADI (mg/kg body mass), m = body mass (60 kg), B = daily dose (kg).
• Exemptions: Competent authority may waive testing if pesticide use history is fully documented per GACP.

Applications and users

ISO 22258:2020 is intended for:

• Quality control and analytical laboratories testing pesticide residues in TCM.
• TCM manufacturers and herbal suppliers ensuring compliance with safety limits.
• Regulatory authorities, pharmacopoeia committees and import/export inspectors harmonizing residue testing.
• Researchers developing validated GC-based residue methods for herbal matrices.

Related standards and guidance

• Annex B references maximum limits from the European Pharmacopoeia and US Pharmacopoeia.
• Annex C provides recommended limits aligned with WHO and FDA/EPA guidance.
• Prepared by ISO/TC 249 (Traditional Chinese medicine).

Keywords: ISO 22258:2020, pesticide residues, Traditional Chinese Medicine, TCM, gas chromatography, GC, Chinese materia medica, pesticide limits, sampling, validation, ADI, GACP.