Analysis of chlorobenzenes in soils by headspace solid-phase microextraction and gas chromatography ion trap mass spectrometry

Headspace solid-phase microextraction (SPME) with gas chromatography-ion trap mass spectrometry (GC-IT-MS) was investigated as a possible alternative to Soxhlet extraction in the analysis of chlorobenzenes in soils. A 100 mu m polydimethylsiloxane fibre was used for the optimization studies. Maximum sensitivity was obtained at a sampling temperature of 30 degrees C and with an absorption time of 25 min. The effect of the addition of solvents of different polarity was evaluated. Better repeatability (R.S.D. between 5 and 7%) and higher responses were obtained when water was added to the soil. The headspace SPME method was applied to the analysis of the chlorobenzenes, 1,2,3-trichlorobenzene, 1,2,3,4-tetrachlorobenze and pentachlorobenzene, in an industrially contaminated sandy soil, CRM-529 (Candidate Reference Material). The chlorobenzenes in this soil were quantified by standard addition, which led to good reproducibility (R.S.D. between 3 and 5%) and adequate detection limits (0.03 to 0.1 ng g(-1) of soil). The method was validated by comparing the results with those obtained in a European intercomparison exercise.