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The Purity Test

ImpuritiesObject of the test

The object of the purity analysis is to determine the percentage composition by weight of the sample being tested and by inference the composition of the seed lot and to identify the various species of seeds and inert particles constituting the sample.

General principles

A prescribed weight of seed is examined by a trained analyst and the various constituents found are identified, weighed and reported. In seed testing we only identify down to species level therefore a purity test will give no indication of seed variety.


All seed offered for sale within the E.U. must conform to purity standards. The following are the minimum standards for some commonly tested species:

Species  Minimum purity standard 
Barley  98%
Wheat  98%
Oats  98%
Perennial ryegrass  96%
 Oil seed rape 98%

Purity test reports

The purity test report states the percentage of pure seeds found in the examined prescribed weight. The report will also state what inert matter was found & may include the following:

  • Broken seed, soil, scraps
  • Other seed: All seed other than the stated species
  • Ergot: Ergot is a fungus of the genus Claviceps
  • Pests: Any live pests insects etc.  

Latin names

Genus and species names are reported in Latin. Attached is a species list of Latin and common names found in Irish crops Species List (pdf 87Kb)