Steady-state kinetic model for headspace solvent microextraction

A general kinetic model for headspace solvent microextraction (HS-SME) is described which incorporates steady-state behavior of the concentration of the analyte in the headspace phase during the extraction process. The model is consistent with previously reported extraction rate data, and provides a fundamental framework for understanding the rate-controlling characteristics of this method. The assumptions of the model are challenged with experimental studies of HS-SME using the relatively volatile BTEX series (benzene, toluene, ethylbenzene and xylene) in which both the organic phase and headspace phase concentrations are measured directly and independently at different times during the extraction process. The experimental data provide insight into the utility and limitations of the model.