ISO 19609-3:2022

Overview

ISO 19609-3:2022 - Traditional Chinese medicine - Quality and safety of raw materials and finished products made with raw materials - Part 3: Testing for contaminants - specifies sample preparation methods for determining contamination of natural products used in Traditional Chinese Medicine (TCM). The standard covers preparation and handling for analysis of heavy metals, pesticides, aflatoxins and microorganisms in both raw materials and finished TCM products, ensuring reliable downstream measurement and reporting.

Key topics and technical requirements

• Scope and purpose: Defines sample preparation protocols tailored to TCM matrices so analytical results for contaminants are accurate and reproducible.
• Sample types and sizes: Guidance for solids, semi-solids and liquids. Typical test sample: 250 mg dry (or equivalent); solid test material particle size generally < 1 mm.
• Solid handling: Grinding and sieving of crude materials, tablets, capsules, granules and powders as referenced to ISO 19609-1:2021.
• Microwave digestion for heavy metals:
  • Use of high‑pressure PTFE microwave vessels and trace‑analysis grade reagents (distilled water, concentrated HNO3, 30% H2O2).
  • Microwave apparatus energy ~600 W with a defined heating/cooling sequence.
  • Two extraction solutions described: Solution A (3 ml HNO3 + 1 ml H2O2) for low-carbohydrate samples; Solution B (1.2 ml HNO3 + 0.4 ml H2O2 + 2.5 ml water) for higher-carbohydrate samples.
  • Caution: using Solution A on high-carbohydrate samples can cause dangerous pressure events.
• Extraction and sample solution: Procedures include filtration and dilution to a defined volumetric endpoint (e.g., 10 ml) prior to measurement.
• Measurement and validation: Measurement methods reference ISO analytical standards (e.g., ISO 18664 for heavy metals) and require method validity checks and reporting of results.

Applications and users

• Who uses it: TCM manufacturers, quality assurance/quality control teams, analytical chemists, contract testing laboratories, regulatory authorities and import/export compliance teams.
• Practical uses:
  • Prepare samples correctly for ICP/MS, AAS, GC, LC-FLD or microbiological assays.
  • Support safety assessments, regulatory submissions and market access by demonstrating contaminant control.
  • Reduce analytical variability and false results through standardized sample preparation.

Related standards

• ISO 19609-1:2021 - General requirements
• ISO 18664 - Determination of heavy metals in herbal medicines
• ISO 22258 - Determination of pesticide residues by GC
• ISO 22283 - Determination of aflatoxins by LC-FLD
• ISO 22467 - Determination of microorganisms in natural products

Keywords: ISO 19609-3:2022, Traditional Chinese Medicine, TCM contaminants, sample preparation, heavy metals, pesticides, aflatoxins, microorganisms, microwave digestion, quality and safety.