Second Order Kinetic Modeling of Headspace Solid Phase Microextraction of Flavors Released from Selected Food Model Systems

The application of headspace-solid phase microextraction (HS-SPME) has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and chemical reactor modeling was developed, describing the kinetic behavior of aroma active compounds extracted by SPME from two different food model systems, i.e., a semi-solid food and a liquid food. The model accounted for both adsorption and release of the analytes from SPME fiber, which occurred simultaneously but were counter-directed. The model had four parameters and their estimated values were found to be more reproducible than the direct measurement of the compounds themselves by instrumental analysis. With the relative standard deviations (RSD) of each parameter less than 5% and root mean square error (RMSE) less than 0.15, the model was proved to be a robust one in estimating the release of a wide range of low molecular weight acetates at three environmental temperatures i.e., 30, 40 and 60 degrees C. More insights of SPME behavior regarding the small molecule analytes were also obtained through the kinetic parameters and the model itself.