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Primary Reference Materials (PRMs) offer

Ensure measurement comparability to the highest level of precision and traceability

NPL’s 30 component Ozone Precursor primary reference material (PRM) and NPL's nitrogen monoxide (NO) PRMs are recognised by the World Meteorological Organisation Global Atmospheric Watch (WMO-GAW) programme as their primary standard for ten non-methane hydrocarbons (NMHCs) and for nitrogen oxides (NOx) that have been identified as critical to be monitored in the long-term to enable assessments of changes in the chemical composition of the atmosphere to be determined on a global scale.

For a limited time NPL is offering a 15% discount on the 30 component NMHC (Ozone Precursor) and NO PRMs with guaranteed product stability of up to 5 years.

Register your interest

NPL PRMs are produced gravimetrically according to ISO 6142-1, are traceable to the international system and units and represent the highest point in the traceability chain.


NMHC (Ozone Precursor O3P) PRM


Amount fraction

4 nmol mol-1

50 µmol mol-1

Expanded uncertainty

2 – 3 %

0.5 %


< 5 years

< 5 years


100 bar

100 bar


10L (1000 L)

10L (1000 L)

Outlet valve

DIN477 No. 1

BS341 No. 14 or DIN477 No. 8


This competitive offer is provided with an accredited certificate specifying all amount fractions, associated uncertainties and guaranteed product stability of up to 5 years.


NPL Primary reference mixture 

Normal price 

Discounted price 

Price reduction 


Ozone Precursor (4 nmol/mol) 



15 % 

Offer ends 30 September 2024

Nitrogen monoxide (50 μmol/mol) 



15 % 

Offer ends 30 September 2024

Routine measurements of air pollutants such as oxides of nitrogen and non-methane hydrocarbons must be performed to fulfil the requirements of the European Directive on ambient air quality and cleaner air for Europe (2008/50/EC).

To ensure legislative compliance and ensure accurate measurements there is a requirement for stable and accurate reference materials to facilitate the traceable calibration of analytical instrumentation.

Are you looking to purchase new PRMs or to renew your primary reference materials after this offer has expired? 

For help with NPL primary reference material orders and any future requirements, please provide as much detail as possible and we will be in contact.

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Find out more about our Gas reference materials

See NPL’s wide range of reference gas mixtures tailored to suit the needs of multiple industry sectors

Gas reference materials