Overview
ISO 1839:1980 - "Tea - Sampling" sets out standardized methods for obtaining representative tea samples from containers of all sizes. The standard defines key terms and describes required apparatus, general sampling principles, procedures for sampling from containers, packaging and labelling of samples, dispatch requirements and the contents of the sampling report. Its purpose is to ensure samples are representative and protected from contamination, moisture and other alterations.
Key Topics
- Scope and definitions: Applies to sampling from containers of all sizes. Important terms include elementary (incremental) sample, composite (global) sample and laboratory sample.
- Apparatus: Examples include spoons, ladles, probes or other instruments suitable for withdrawing sample increments and an appropriate dividing device to reduce a composite sample to laboratory portions.
- Random sampling: Packages to be sampled are selected at random. The standard describes practical random selection methods (for example using step intervals where r = N/n) to obtain the required number of containers from a lot.
- Increment and composite sampling: Elementary samples are taken from different points of a lot and combined into a global (composite) sample which is then mixed and reduced to laboratory samples.
- Minimum sample sizes: Practical guidance includes minimum incremental and laboratory sample masses used in testing. For example, individual increments of at least 50 g are recommended; laboratory samples for chemical analysis should generally be at least 100 g (50 g for sensory analysis), unless otherwise agreed.
- Packaging and storage: Samples should be placed in dry, odour-free, airtight containers (e.g., aluminium or tinplate) and protected from light. Samples for moisture determination must be stored in airtight containers and sealed.
- Labeling and reporting: Each sample container must be clearly labelled with sample origin, date, lot and sampler identity. A sampling report (procès-verbal) should record location, dates, personnel, sampling method and any abnormalities or environmental conditions (e.g., relative humidity) that could affect results.
- Dispatch: Samples should be dispatched promptly - normally within 48 hours of sampling (non-working days excluded) - and, where required, duplicate samples retained as reference.
Applications
ISO 1839:1980 is used by tea producers, exporters, importers, testing laboratories and inspectors to:
- Ensure representative samples for chemical, physical and sensory testing
- Reduce commercial disputes by standardizing sampling practice
- Preserve sample integrity during storage and transport
Related Standards
- ISO standards on statistical terminology and sampling where referenced
- National or regional standards for tea quality testing and laboratory analysis
This standard provides practical, internationally accepted guidance to obtain, handle and document tea samples so test results are reliable and reproducible.
