ISO 19609-4:2022

Overview

ISO 19609-4:2022 - Traditional Chinese medicine: Quality and safety of raw materials and finished products - Part 4: Testing for preservatives and unwanted compounds - specifies analytical approaches and quality-control requirements for detecting preservatives and unwanted compounds in raw materials and finished traditional Chinese medicine (TCM) products. The standard is part of the ISO 19609 series and guides laboratories and manufacturers on screening, quantitative testing and declaration of contaminants such as sulfur derivatives, ethylene oxide, irradiated material and toxic degradation products.

Key technical topics and requirements

• Scope: Defines testing within a risk‑assessment framework for starting materials and finished TCM products.
• Categories of unwanted compounds: preservatives, radiation (irradiated materials), toxic compounds (natural toxins and degradation products) and other additives.
• Declaration: Preservatives must be declared on product labels or Certificates of Analysis (CoA).
• Sulfur and sulfur derivatives:
  • Elemental sulfur screening: sample washing, filtration and drying; heating residue to detect characteristic gas/odour.
  • Quantification of sulfur derivatives as sulfur dioxide: apply ISO 22590 or equivalent validated methods.
  • Quick qualitative screening: lead‑acetate test after acid/zinc treatment; sample milled <1 mm.
• Ethylene oxide (EO):
  • Recommended headspace gas chromatography (headspace‑GC) with flame ionization detector (FID).
  • Sample prep example: 1.0 g sample in 10‑ml headspace vial, suspended in water and equilibrated (70 °C, 45 min).
  • System suitability: peak resolution (e.g., acetaldehyde vs. EO) ≥ 2.0; repeatability criteria (RSD limits).
  • Results reported as ppm; tests run in triplicate and compared with reference solutions.
• Irradiation detection: Use photostimulated luminescence as per ISO 22256 for identifying irradiated natural products.
• Toxic compounds: Addresses methods for natural toxins and toxins from degradation; annexes include materia medica and chromatogram examples.

Practical applications and users

• Quality control (QC) and analytical chemistry laboratories testing TCM raw materials and finished products
• TCM manufacturers, contract manufacturers (CMOs) and suppliers needing CoA and labeling compliance
• Regulatory authorities and import/export inspectors assessing product safety and conformity
• Research labs validating methods for preservative residues, ethylene oxide and irradiation status

Related standards

• ISO 19609 series (other parts)
• ISO 22256 - Detection of irradiated natural products by photostimulated luminescence
• ISO 22590 - Determination of sulfur dioxide in natural products
• ISO 23190 - Determination of aristolochic acids by HPLC
• ISO 23956 - Determination of benzopyrene
• ISO 23962 - Processed Aconitum carmichaelii lateral root

Keywords: ISO 19609-4, traditional Chinese medicine, preservative testing, ethylene oxide, sulfur dioxide, photostimulated luminescence, TCM quality control, unwanted compounds.