cen:proj:78116

Ambient air — Standard method for the measurement of organic ozone precursor concentrations — Part 4: Diffusive sampling followed by thermal desorption and gas chromatography

Scope

This document gives general guidance for the time-weighted average monitoring of organic ozone precursor vapours (VOCs) in air by diffusive sampling onto sorbent tubes or cartridges followed by off-line analysis using thermal desorption and capillary gas chromatography. This document is valid for the measurement of organic ozone precursor vapours ranging in volatility from C4 to C14 hydrocarbons in a concentration range of approximately 0,5 μg/m3 to 50 μg/m3. Air samples are typically collected over periods ranging from a few hours to 14 days. Airborne concentrations of less or higher volatile compounds can also be measured using this standard provided appropriate sorbents are used in the samplers. The upper limit of the useful range is set by the sorptive capacity of the sampler and by the linear dynamic range of the gas chromatograph column and detector or by the sample splitting capacity of the analytical instrumentation used. The lower limit of the useful range depends on the noise level of the detector and on blank levels of interfering artefacts on the sampler and in the analytical system. Artefacts are typically low ng or sub ng for diffusive samplers packed with graphitised carbon sorbents or carbonised molecular sieves, but higher levels of organic compounds have been noted in diffusive samplers packed with other sorbents – e.g. porous polymers. The detection limit will be approximately 1/10 of the lower concentration range of interest. This document provides general guidance for the sampling of organic ozone precursor vapours using a single diffusive sampler or multiple diffusive samplers used in parallel.

Related legislation

Legislation related to this standard