Kinetic calibration using dominant pre-equilibrium desorption for on-site and in vivo sampling by solid-phase microextraction.

A new kinetic calibration was developed using dominant pre-equilibrium desorption by solid-phase microextracton. The calibration was based on isotropism between absorption and desorption, which was proved theoretically and experimentally in an aqueous solution and semisolid matrix. This approach allows for the calibration of absorption using desorption to compensate for matrix effects. Moreover, concentration profiles are initially proposed to verify isotropism between the absorption and desorption, while providing a linear approach to obtain time constants for the purpose of quantitative analysis. This linear approach is more convenient, robust, and accurate than the nonlinear version with the previously used time profiles. Furthermore, the target analytes are used as the internal standards; thus, radioactive or deuterated internal standards are not necessary. In addition, dominant pre-equilibrium desorption utilizes the pre-equilibrium approach and offers a shorter sample preparation time, which is typically suitable for in vivo sampling. This kinetic calibration method was successfully applied to prepare samples of polycyclic aromatic hydrocarbons in a flow-through system and in vivo pesticide sampling in a jade plant (Crassula ovata).