In vivo SPME does not yet offer real-time data, but, as recently presented, the method has the potential to be used for monitoring biochemical-profile changes as well as discovery and monitoring of biomarkers during surgery [6]. At its first stage, the sampling method was optimized using liver and lung grafts. The authors indicated compounds discriminating in vivo versus ex vivo extraction data, and proved there was negligible invasiveness when both types of probe, non-assembled and hypodermic needle assembled SPME, were used for DI sampling.As for the blood[5] and brain [73] studies, the mix-mode coating was used. The extraction from liver tissue showed a larger number of metabolites obtained compared to lung tissue,and,inbothcases,more compounds were detected in positive ionization mode using an Orbitrap mass spectrometer coupled to an LC system. The on-site sampling (extraction) took 20 min and 30 min for lung and liver, respectively, and was followed by trans- portation to the analytical laboratory for further procedures.However, considering that LC-MS analysis, particularly determination of targeted biomarkers, can be as fast as a few minutes, and that the bottleneck of tissue analysis is sample preparation, the proposed variant can be a valuable addendum to tissue-extraction protocols.