Overview
ISO 22195-7:2024 specifies a laboratory test method for identifying the index ingredient of Himalayan rhubarb in coloured textiles. The standard describes sample preparation, reagent and apparatus requirements, chromatographic analysis (LC‑MS and HPLC‑DAD) and calculation procedures to detect emodin and related marker compounds from Himalayan rhubarb dye extracts. While the scope refers to extracts from Himalayan rhubarb flowers, the published procedure uses ethanol extraction combined with LC‑MS/HPLC‑DAD detection to confirm the presence and quantify emodin in textile samples.
Key topics and technical requirements
- Scope and principle: Identification of characteristic natural colourant constituents (notably emodin) by chromatography; detection of an index component is indicative but not exclusive proof of Himalayan rhubarb use.
- Reagents: HPLC‑grade water (ISO 3696), ethanol, acetonitrile, 30% formic acid, and an emodin reference standard (≥~90% purity).
- Apparatus: analytical balance (0.001 g), ultrasonic bath (30 ± 2 °C), 50 ml borosilicate containers, 0.2 µm membrane filters, LC coupled with mass spectrometer (LC‑MS) and optional HPLC‑DAD.
- Procedure:
- Standard preparation: emodin stock and at least five calibration points (e.g., 1, 10, 20, 50, 100 mg/L).
- Specimen prep: cut ~1 g of textile into ~5×5 mm pieces, extract with 10 ml ethanol in an ultrasonic bath for 20 ± 1 min, cool, filter and dilute as needed.
- Analysis: LC‑MS (ESI ±) for detection/qualification; HPLC‑DAD (430 nm) can be used for complementary detection.
- Calibration and quantification: Calibration curve using peak area; correlation coefficient requirements given (calibration R values specified in the standard). Calculation converts extract concentration to µg/g using the provided formula (accounts for dilution factor, extraction volume and specimen mass).
- Reporting: test report must reference ISO 22195‑7:2024 and include specimen ID, emodin detection result, chromatographic conditions, any deviations and test date.
Applications and users
- Textile testing laboratories performing dye identification and natural‑dye verification.
- Quality control and compliance teams verifying natural dye claims or origin labeling.
- Museum conservation and forensic analysts investigating historic or archaeological textiles.
- Academic researchers studying plant‑based dyes and dye chemistry.
- Supply‑chain auditors assessing artisanal dyeing processes and authenticity.
Keywords: ISO 22195-7:2024, Himalayan rhubarb, emodin, textile dye identification, LC‑MS, HPLC‑DAD, natural colourant, extraction protocol.
Related standards
- Other parts of the ISO 22195 series (for additional natural colourant methods).
- ISO 3696 - Water for analytical laboratory use (normative reference used in ISO 22195‑7:2024).
Open preview (PDF)Textiles — Determination of index ingredient from coloured textile — Part 7: Himalayan rhubarb
