ANALYSIS OF CHLOROANILINES AND NITROANILINES AND NITROBENZENES IN SOILS BY HEADSPACE SOLID-PHASE MICROEXTRACTION

Quantitative analysis by headspace solid-phase microextraction (HS-SPM E) of twenty chloro- and nitrobenzenes and anilines spiked into soil s amples was possible when the calibration was performed with the same m atrix. The SPME response increased with addition of water to the air d ried soil samples, and by optimisation of extraction conditions such a s temperature, extraction time and sample agitation. Distribution cons tants between the fibre coating materials and water were determined. T hey showed that polyacrylate, rather than polydimethylsiloxane, should be used in the analysis of polar compounds. Matrix effects, mainly de pending on the organic carbon content of the soil, were so large that quantitative analyses of real soil samples would not be reliable with model matrix calibration. This problem would be overcome if a nearly e xhaustive extraction could be achieved. Recovery studies showed that t his was possible only in the case of extraction of the lightest non-po lar analytes from a soil with a very low content of organic carbon. In stead quantification could be performed with calibration by standard a ddition. By this approach the non-linear calibration curves at concent rations near the detection limits would cause inaccurate results at tr ace level, whereas it could be applied successfully within the linear ranges. Hence, the potential of HS-SPME in soil analysis is primarily as a rapid screening technique.