Aromatic Oils - testing for Aromaticity, PAHs

The UK Environmental Agency has warned that manufacturers and importers of extender oils and tyres must test their products to determine the PAH concentration, For tyres the requirement is BS ISO21461.

Rubber Consultants has ISO17025 accreditation via UKAS forBSISO21461:2009, Rubber -Determination of the aromaticity of oil in vulcanised rubber compounds.

TARRC/Rubber Consultants’ in-house method 093 for this procedure is UKAS accredited to ISO/IEC 17025:2005, general requirements for the competence of testing and calibration laboratories. It covers the sample preparation, the operation of the instrument, and also includes the running of a known reference oil with each set of samples to validate the system.

Rubber Consultants also carries out sub-contract testing to ISO21461 for a number of other testing organisations.

The NMR method provides a measure of polyaromaticity in a purified dry residue extracted from the rubber. The molecular structure of certain non-linear PAHs with 3 or more fused rings contains a characteristic 3-sided concave area at the periphery of the molecule. The hydrogen atoms in this area are called bay region hydrogens. The level of these ‘bay protons’ is used as an indication of aromaticity for compliance with EC 552/2009 REACH (EC 1907/2006 Annex XVII amendment).

EC 552/2009 REACH states that PAH rich extender oils in tyre production after 1 January 2010 should not exceed 0.35 Bay proton, as measured and calculated by ISO 21461.

The ISO method requires extraction of the oils from the rubber compound, triplicate purification with solvent elution though silica cartridges and triplicate NMR analysis must then be performed.

A sample is defined as one portion of oil or cured rubber compound sheet or part of a tyre. If a tyre requires sampling in more than one place then each portion of the tyre must be treated as a separate sample.

For further information please contact us.

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