Gas Chromatography: MCERTS Certification for Ambient Air Analysis on Benzene and VOCs
Due to environmental issues, the world of gas analysis is evolving very rapidly.Governments set the rules to limit and control the environmental pollution through legislation.Volatile organic compounds (VOCs),often produced by human activities, are amongst the sources of pollution that need to be identified and quantified for safety reasons. Exposure to high concentrations of certain VOCs is dangerous, even for short times, and the impact of low concentrations of VOCs on people’s health and environment has also become amajor concern in recent years.The concentration of such compounds can be very different depending on themeasurement area and it is a considerable technological challenge to analyse precisely and continuously the VOCs present in air within industrial walls or at the top of amountain using the same instrument. Presently,only benzene is regulated,but there aremoves tomeasure other VOCs which are known to be ozone precursors.
Since 1986,Chromatotec® has been recognisedworldwide for their accurate gas analysis, renowned for analysis in the field of ambient air monitoring and natural gas.Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analysing compounds that can be stable in the vapour state.Chromatotec’s products allowthe quantification and identification of compounds over awide range of concentrations (including ppt,ppb,ppmand%levels) using gas chromatography analysers.
In gas chromatography, themobile phase is a carrier gas,usually an inert gas such as helium,hydrogen or an unreactive gas such as nitrogen or argon.Themobile phase carries the sample to be analysed through a column in order to separate the compounds.The time atwhich the compounds elute fromthe column is used to identify the different species whereas the electric intensitymeasured by the detector allows for quantification. In order to verify the quality of our instruments, Chromatotec® has performed tests and obtained certifications relating to relevant standards,performed by bodies recognisedworldwide.
Furthermore, to be compliantwith European,Chinese and American performance standards,Chromatotec® hasworked and invested in the development and improvement of rapid and accurate analysers.
For Continuous Ambient AirMonitoring Systems (CAMS), the Certification Scheme calledMCERTS defines tests and performance criteria for the measurement of benzene concentrations and otherVOCs using an automated sampling pumpwith in-situ gas chromatography.There is also a harmonised European standard relating to themeasurement of benzene, which is known as EN 14662-3. In the near future,Chromatotec®will be certified ISO17025 formeasurements of benzene and certain otherVOCs.
The National Physical Laboratory (NPL -London) is currently one of only a fewISO17025 accredited European laboratories to performbenzene laboratory and field tests.The NPL in collaborationwith airmotec/Chromatotec® proposed a Laboratory and FieldTest Programme for approval to Sira Environmental Limited.Sira is the certification body which oversees theMCERTS certification on behalf of the Environment Agencywhich is an Executive Non-departmental Public Body responsible to the Secretary of State for Environment,Food and Rural Affairs in the UK.
To verify and ensure the accurate performance of Chromatotec’s analysers, four CAMS,using two different detector technologies,were simultaneously tested by NPL in their specialised ambient air quality test laboratory in accordancewith UKAS-accredited NPL Test Procedure QPAS/B/528a (and later on in the field) and compared against the performance criteria defined in theMCERTS standard for CAMS and EN 14662-3.Both types of CAMS were cyclic automated analysers which sample a knownmeasured volume of air through a sorbent mediumfor a fixed period of time, and then analyse the amount of the target determinands, trapped using a gas chromatograph.One type of CAM(airmoVOC) employed a Flame Ionisation Detector (FID) tomeasure the determinandswhile the second type of CAM(airTOXIC) used a Photo Ionisation Detector (PID).