This document gives general guidance for the sampling and analysis of benzene in air by pumped sampling, thermal desorption and capillary gas chromatography.
This document is in accordance with the generic methodology selected as the basis of the European Union reference method for the determination of benzene in ambient air [1] for the purpose of comparison of measurement results with limit values with a one-year reference period.
This document is valid for the measurement of benzene 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 7 days.
The upper limit of the useful range is set by the sorptive capacity (the safe sampling volume) of the sorbent 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 benzene and/or interfering artefacts on the sorbent. Artefacts are typically sub ng for graphitised carbon sorbents, but higher levels of aromatic hydrocarbons have been noted in other sorbents - e.g. porous polymers. The detection limit will be approximately 1/10 of the lower concentration range.
This document provides general guidance for the sampling of benzene using either a single sampler, which is changed manually after every exposure period, or a multi-sampler capable of storing and exposing multiple samples without user intervention.