Rapid Analysis of Biological Samples Using Monolithic Polymer-Based In-Tube Solid-Phase Microextraction with Direct Mass Spectrometry

Online coupling in-tube solid-phase microextraction (SPME) with mass spectrometry (MS) was achieved by directly utilizing a monolithic SPME capillary as the electrospray emitter. A porous organic polymer with a highly porous structure can not only provide excellent extraction efficiency due to its high specific surface area but also increase the ionization efficiency and stability by producing smaller electrospray droplets. This online coupling strategy significantly simplifies the device as well as the operation process. The whole analytical process only takes about 12 min with a sample amount of 100 μL. By choosing an ionic liquid-based organic polymer with high extraction ability and good stability and adjusting a suitable porous structure for better electrospray, the developed in-tube SPME-MS method showed excellent extraction performance and good reusability without clogging events. As a proof of concept, the proposed method was applied for the analysis of non-steroid anti-inflammatory drugs in plasma and urine samples. The method showed a wide linear range (0.1-200 ng/mL), good linearity (R² ≥ 0.99), and good reproducibility (intra-day relative standard deviations (RSDs) <3.00% and inter-day RSDs <6.29%).