Electrospray Ionization Mass Spectrometry Technique - ESI-MS

Key Features of Electrospray Ionization Mass Spectrometry

• The ability of ESI to generate multiply charged ions enhances the sensitivity of mass spectrometry, enabling the accurate detection of large biomolecules with minimal fragmentation.
• With its high-pressure dispensing capability, enhanced precision, durable design, and optimization for high-throughput workflows, the system ensures accurate liquid handling and reliable lab performance.
• The instrument combines dual-source technology with high-performance analytical capabilities.
• The electrospray ionization mass spectrometer offers high sensitivity for low-level detection, robust and reliable performance, and high-throughput capabilities, all within a compact design supported by an intuitive software interface for streamlined operation in complex analytical tasks.
• The system delivers accurate mass measurements (m/z 50–4000) with a resolution of 60,000, supporting multiple fragmentation techniques such as pulsed-Q dissociation (PQD) and collision-induced dissociation (CID) for reliable structural elucidation. Using an ESI source, it enables precise molecular weight determination with minimal sample volume.
• With advanced ion focusing, ultrafast technologies, and a robust, low-maintenance design, the system ensures trace-level quantitative detection, high data quality, and long-term performance even with complex biological or food samples. Offering ultrafast scan speeds, rapid polarity switching, flexible ionization modes, and intuitive software with enhanced MRM optimization and streamlined data review, it delivers reproducibility and ease of use.

Applications of ESI-MS

• Clinical applications: ESI-MS is increasingly important in clinical laboratories due to its ability to analyze femtomole samples in microliter volumes, enabling sensitive and reliable detection of metabolites for diagnosing inborn errors of amino acid, fatty acid, purine, and pyrimidine metabolism, as well as galactosaemia and peroxisomal disorders. In addition, it preserves noncovalent interactions for identifying Hb variants, supports IFCC-standardized HbA1c assays, and finds expanding applications in therapeutic drug monitoring and biomarker identification.
• Protein identification and structural characterization: ESI-MS has become a cornerstone in proteomics, enabling rapid and precise protein identification, sequencing, and characterization through both bottom-up and top-down approaches, while also detecting mutations and posttranslational modifications. Its ability to analyze peptide mass fingerprints, monitor conformational changes, and map disulfide linkages makes it an indispensable tool for understanding protein structure, function, and dynamics.
• Noncovalent Interactions: ESI-MS enables the transfer of solution-phase noncovalent complexes into the gas phase, allowing detailed investigation of weak forces such as hydrogen bonding, electrostatic interactions, and hydrophobic effects that stabilize biomolecular assemblies. This technique has been widely applied to study protein-protein, protein-ligand, protein-nucleic acid, and small peptide complexes, providing insights into interaction strengths, binding constants, and even challenging systems like membrane protein complexes.
• Mechanistic and catalysis research: ESI-MS has emerged as a powerful tool for probing reaction mechanisms and catalytic processes, enabling the direct detection of intermediates and molecular species under mild conditions. By establishing correlations between gas-phase data and solution-phase behavior, it provides valuable insights into reaction pathways, catalyst performance, and mechanistic validation.
• Probing molecular dynamics with H/D-exchange: ESI-MS coupled with H/D-exchange experiments enables the study of molecular dynamics by trapping analyte ions and allowing controlled reactions with deuterated molecules. This provides insights into motions within noncovalent complexes, such as the tumbling of ammonium guests in resorcinarene hosts or the dynamic “wire dance” of crown ethers along oligolysine chains. These experiments also allow monitoring of protein folding/unfolding, reveal conformational states in vacuum, and support gas-phase covalent modification studies.
• Monitoring reactions and intermediates: ESI-MS has become a valuable tool in synthetic organic and organometallic chemistry for probing reactive intermediates and elucidating mechanisms, as demonstrated in studies of Suzuki and Heck reactions, Ni[II] complexes, and Bayer-Villiger type solid-state reactions. It has also enabled the identification and characterization of reactive species such as adamantyl and tert-adamantyl peroxyl radicals.
• Chemical imaging with DESI-MS: DESI-MS enables ambient, label-free chemical imaging by mapping the spatial distribution and identifying the structure of molecules in biological tissues, including drugs and their metabolites, without the need for radioactive labels. While still an emerging technique, ongoing research aims to improve sensitivity, ionization efficiency, and tissue-specific analysis, expanding its potential for detailed medical and pharmaceutical applications.

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