Used Thermo Q Exactive Plus LC-MS/MS

The Thermo Scientific Q Exactive Plus is a high-performance hybrid quadrupole-Orbitrap mass spectrometer designed for high-resolution, accurate-mass (HR/AM) analysis. It combines the precursor ion selection capability of a quadrupole with the high-resolution detection of an Orbitrap mass analyzer, making it a versatile tool for both qualitative and quantitative applications in proteomics, metabolomics, and biopharmaceutical characterization.

Technical Specifications and Core Features

The Q Exactive Plus operates with a mass range of 50 to 6,000 m/z and achieves a resolving power of up to 140,000 (FWHM at m/z 200), with an optional enhanced resolution mode reaching 280,000. It delivers exceptional mass accuracy, typically better than 1 ppm with internal calibration and better than 3 ppm with external calibration. The system features a fast scan rate of up to 12 Hz, which is well-suited for ultra-high-performance liquid chromatography (UHPLC) separations, and it can perform rapid polarity switching in less than one second. Its dynamic range exceeds 5,000:1, and it offers high sensitivity, capable of detecting femtogram levels of compounds on-column.

Key hardware advancements include the Advanced Quadrupole Technology (AQT), which provides superior precursor ion isolation with narrow isolation windows (down to 0.4 Da), improving selectivity and reducing interferences. The system also incorporates an Advanced Active Beam Guide (AABG) that reduces chemical noise and enhances robustness, particularly for complex sample matrices. The instrument utilizes Higher-energy Collisional Dissociation (HCD) for fragmentation, providing high-quality MS/MS spectra for confident compound identification.

Applications and Workflow

The Q Exactive Plus is widely used in proteomics for bottom-up protein identification and quantification, including label-free and isobaric tagging (e.g., TMT) workflows. Its high scan speed allows for deep proteome coverage, while its high resolution enables the differentiation of isobaric species. In metabolomics and lipidomics, the instrument's high mass accuracy and resolution are critical for identifying and confirming small molecules and lipids in complex biological samples.

For biopharmaceutical applications, the Q Exactive Plus offers an optional Intact Protein Mode and High Mass Range (HMR) capabilities. This allows for the analysis of intact proteins, monoclonal antibodies (mAbs), and antibody-drug conjugates (ADCs) under native or denaturing conditions, providing insights into protein mass, post-translational modifications (PTMs), and higher-order structure.

The system supports various data acquisition modes, including full-scan MS, data-dependent acquisition (DDA), data-independent acquisition (DIA), and targeted methods like Parallel Reaction Monitoring (PRM). PRM leverages the high resolution of the Orbitrap to monitor specific fragment ions with high selectivity, making it a powerful alternative to traditional triple quadrupole MRM methods for targeted quantification.

In summary, the Thermo Q Exactive Plus LC-MS/MS is a robust and flexible platform that delivers high-quality data for a broad range of research applications, from discovery screening to targeted quantification and biotherapeutic characterization.