ISO 20752:2023

Overview

ISO 20752:2023 - "Cork stoppers - Determination of releasable 2,4,6‑trichloroanisole (TCA)" specifies a laboratory test method to quantify releasable TCA from all types of cork stoppers and their constituents. The standard defines the sampling, maceration, extraction (SPME), chromatographic separation and detection steps (GC‑MS or GC‑ECD), calibration range and reporting requirements used to assess cork-related cork taint risk in wine packaging.

Key topics and technical requirements

• Scope: Applicable to all types of cork stoppers and cork constituents; measures releasable 2,4,6‑trichloroanisole (TCA).
• Sample preparation: Maceration in a 12 % (v/v) hydroalcoholic simulant (simulating wine) for 24 h ± 2 h at ambient test conditions of (21 ± 4) °C. Sample quantities and vial volumes are specified (examples given for different stopper types).
• Extraction: Headspace solid‑phase microextraction (SPME) is used; example fiber PDMS 100 µm. Salt addition (approx. 3 g NaCl) and internal standard spiking are included to improve sensitivity and repeatability.
• Chromatography and detection:
  • GC‑MS (SIM or MS/MS mode) with specified quantifying and qualifying ions; quantification typically by the most abundant ion.
  • GC‑ECD as an alternative detector with identification by retention time comparison to standards.
• Calibration: Calibration range example from 0.5 ng/L to 50 ng/L in simulant wine; internal standards recommended (e.g., TCA‑d5 or 2,3,6‑TCA for MS; 2,6‑dibromoanisole for ECD).
• Operating parameters: Example SPME headspace adsorption (PDMS 100 µm: 15 min at 35 °C ± 2 °C), splitless desorption (1–2 min at 250 °C), and a sample temperature program example for GC.
• Quality controls: Blank tests, fiber conditioning, and regular evaluation of calibration curves. Results are reported in ng/L, rounded to 0.5 ng/L (or 0.1 ng/L if measurement uncertainty is reported).
• Reporting: Required elements include sample identification, maceration flask capacity, standard reference to ISO 20752:2023, internal standard used, TCA concentration, detection/quantification limits and any incidents.

Applications and who uses it

• Cork manufacturers and suppliers: incoming/outgoing quality control to reduce cork taint risk.
• Wine producers and bottlers: selection and acceptance testing of closures to protect wine sensory quality.
• Analytical laboratories: routine testing and certification of cork stoppers using validated GC‑MS or GC‑ECD methods.
• Regulatory and certification bodies: compliance assessment and reference for standard test reporting.

Keywords: ISO 20752, cork stoppers, TCA, 2,4,6‑trichloroanisole, SPME, GC‑MS, GC‑ECD, cork taint, quality control.

Related standards

• ISO 633 - Cork vocabulary
• ISO 17727 - Cork stoppers for still wines - sampling plan for quality control