A General Model for the Optimization of Sample Processing Conditions by Solid‐Phase Extraction Applied to the Isolation of Estrogens from Urine

A general model is presented for the prediction of experimental conditions for the isolation of organic compounds from aqueous solution by solid-phase extraction. The solvation parameter model is used to predict the variation of retention as a function of solvent composition from characteristic solute descriptors and combined with a frontal analysis model to adjust the predicted breakthrough volumes to account for the influence of the small number of theoretical plates characteristic of sorbent cartridges. System maps are used to determine breakthrough volumes for sample processing, the composition and volume of wash solvents for matrix simplification, and the composition and volume of eluting solvents. System maps are provided for an octadecylsiloxane-bonded silica sorbent with methanol and acetonitrile as cosolvents with water. These maps are used to calculate the experimental conditions for the isolation of estrogens from urine and the model validated by experimental verification of the model predictions. The proposed approach provides a simple theoretical framework for computer-aided method development in solid-phase extraction.