Analysis of BTEX and other substituted benzenes in water using headspace SPME-GC-FID: method validation

The analysis of BTEX and other substituted benzenes in water samples using solid phase microextraction ( SPME) and quantification by gas chromatography with flame ionization detection (GC-FID) was validated. The best analytical conditions were obtained using PDMS/DVB/CAR fibre using headspace extraction (HS-SPME) at 50 degreesC for 20 min without stirring. The linear range for each compound by HS-SPME with GC/FID was defined. The detection limits for these compounds obtained with PDMS/DVB/CAR fibre and GC/FID were: benzene (15 ng L-1), toluene (160 ng L-1), monochlorobenzene (54 ng L-1), ethylbenzene (32 ng L-1), m-xylene (56 ng L-1), p-xylene (69 ng L-1), styrene (35 ng L-1), o-xylene (42 ng L-1), m-dichlorobenzene (180 ng L-1), p-dichlorobenzene (230 ng L-1), o-dichlorobenzene (250 ng L-1) and trichlorobenzene (260 ng L-1). This headspace SPME-GC-FID method was compared with a previously validated method of analysis using closed-loop-stripping analysis (CLSA). The headspace SPME-GC-FID method is suitable for monitoring the production and distribution of potable water and was used, in field trials, for the analysis of samples from main intakes of water ( surface or underground) and from the water supply system of a large area ( Lisbon and neighbouring municipalities).