High-throughput polymer monolith in-tip SPME fiber preparation and application in drug analysis

Background: A simple, low-cost and reproducible automated procedure has been developed to prepare in-tip solid-phase microextraction (SPME) fibers coated with polymer monoliths using a photopolymerization technique. Up to 96 fibers were prepared at one time using a polymerization mixture consisting of ethylene glycol dimethacrylate, dimethoxy-a-phenylacetophenone and I-decanol. Results: The optimization procedures that affected polymer morphology, such as compositions of the crosslinkers and porogens, polymerization time and fiber thickness as well as extraction efficiency of the immobilized Oasis hydrophilic-lipophilic-balanced extraction sorbent were investigated. Also, the reproducibility of automated in-tip SPME fiber preparation, as well as sample process parameters, such as sample extraction and desorption volumes, are discussed. Conclusion: The performance of the polymer monoliths in-tip SPME assessed with a model drug compound from clinical studies and a head-to-head comparison using in-tip SPME and conventional SPE clearly demonstrated that the SPME is a feasible approach for routine drug analysis in the pharmaceutical industry.