Project Summary Many NIH-funded faculties at Tulane University require state-of-art LC-MS/MS to conduct biomedical research projects intended for clinical translation. A survey of these users revealed several features that were missing from instruments available to Tulane faculty members, while our research on available instruments found one set of instruments that could address these unmet needs: Orbitrap Eclipse Tribrid mass analyzer systems. The proposed ultra-high-sensitive Orbitrap Eclipse Tribrid LC-MS/MS system possesses several unique features that are essential for our research but are not available on our existing platform, such as single-cell proteomics, multistage mass spectrometry (MSn) capability, increased precursor dissociation options, and Real-time Search Synchronous Precursor Selection (SPS MS3) Tandem Mass Tag (TMT) data acquisition mode. We have confirmed that the Orbitrap Eclipse Tribrid mass spectrometer with nano liquid chromatography, UltiMate 3000 RSLCnano (U3000 LC) system meets or exceeds the needs of our user base and offers superior performance relative to other similar available LC-MS/MS systems. The proposed instrument will support the discovery of new biomarkers and the development of new methods of significant biomedical relevance, which we expect will lead to breakthroughs in disease diagnosis, mechanism studies, and targeted therapy. The proposed Orbitrap Eclipse Tribrid mass spectrometry with U3000 nanoLC system represents the next generation of LC-MS/MS system. The instrument provides higher resolution and faster scan speeds, and can perform parallel acquisition to maximize the duty cycle. Our demonstration project with Thermo Scientific showed that the real-time search SPS MS3 method improved identification rates by 30% with higher accuracy and less interference than the MS2 method by Q Exactive HF-x, Tulane’s existing mass spectrometry system. The identification rates via the Data-dependent acquisition (DDA) method increased by 76% using Eclipse with FAIMS Pro interface at the protein level, and increased by 30% using the Data-independent acquisition (DIA)- based label-free method. The requested electron-transfer dissociation method could better support post- translation modification analysis with more confident identification. The new generation tribrid MS gives added experimental throughput while providing depth, coverage, and single-cell proteomics capabilities. These performance characteristics will be highly useful to the large base of Tulane researchers using advanced LC- MS/MS analyses for biomedical research. We have identified an instrument user base of 32 faculty members (12 major users and 20 minor users) funded by NIH or other federal grants. They have requested the features provided by the proposed instrument to conduct their studies, demonstrating the significant need for the requested system. Meeting this need, therefore, is expected to advance multiple high-impact biomedical research project...