ISO 10727:2002

Overview

ISO 10727:2002 specifies a validated laboratory method for the determination of caffeine content in tea and instant tea (solid form) using high‑performance liquid chromatography (HPLC). Applicable to green tea, black tea and decaffeinated tea products, the standard covers sample preparation, extraction, chromatographic conditions, calibration, calculation and reporting to support reliable caffeine quantification.

Key topics and technical requirements

• Scope and applicability: Designed for solid tea matrices (leaf and instant) including decaffeinated products.
• Principle: Caffeine is extracted by refluxing the test portion with water in the presence of dense magnesium oxide, then quantified by HPLC with UV detection.
• Reagents and standards:
  • Grade‑1 water (ISO 3696), HPLC‑grade methanol and specified methanol/water mobile phase.
  • Caffeine stock standard (500 µg/ml) and working standards (e.g., 15, 10, 5, 2 µg/ml) prepared fresh as specified.
• Apparatus and chromatographic conditions:
  • Reversed‑phase C18 column (minimum efficiency recommended), UV detector set between 254–280 nm (≈280 nm preferred).
  • Typical injection volume 20 µl; mobile phase methanol/water ratio adjustable to optimise retention; column temperature commonly ~40 °C (avoid exceeding 60 °C).
• Sample preparation:
  • Grind leaf teas per ISO 1572; test portions: 1.0 g (leaf) or 0.5 g (instant).
  • Reflux with water and MgO for extraction, filter (0.45 µm) and dilute as required (10× for regular teas).
• Calculation and calibration:
  • Build linear calibration curve from standards, compute a response factor (RF), then calculate caffeine mass fraction on a dry‑matter basis using the specified formula and dilution factors.
• Precision: Method precision (repeatability and reproducibility) was evaluated in an interlaboratory study (Annex A); performance depends on matrix and concentration.

Applications and users

ISO 10727 is used for:

• Quality control and routine analytical testing in tea manufacturing and instant beverage production.
• Regulatory compliance and labeling verification of caffeine content.
• Research and product development, including decaffeination process validation.
• Third‑party laboratories, food safety authorities and certification bodies conducting accredited HPLC analyses.

Keywords: ISO 10727, caffeine content, HPLC, high‑performance liquid chromatography, tea testing, instant tea, decaffeinated tea, quality control.

Related standards

• ISO 1572 - Preparation of ground tea sample (dry matter)
• ISO 3696 - Water for analytical laboratory use
• ISO 7513 - Moisture determination for instant tea
• ISO 1839 / ISO 7516 - Sampling of tea and instant tea
• ISO 5725-2 - Method precision evaluation

For laboratories implementing ISO 10727, follow the standard closely for reagent grades, sample handling and reporting to ensure accurate, reproducible caffeine results.