Understanding Mass Spectrometry: From Ion Generation to Spectral Interpretation.

This tutorial provides a structured introduction to mass spectrometry (MS), with particular emphasis on electrospray ionization (ESI)-based measurements. It is intended to support researchers from chemistry and related disciplines in developing a coherent understanding of MS principles, instrumentation, and data interpretation. The architecture of mass spectrometers is outlined, including ion generation, mass analysis, and detection, together with the fundamental processes by which analytes are converted into gas-phase ions. Emphasis is placed on practical interpretation of mass spectra, including isotopic pattern analysis, molecular mass and elemental composition determination, and the evaluation of spectral peak characteristics such as resolution. The role of tandem mass spectrometry (MS/MS) in structural elucidation, particularly in the context of ESI-induced fragmentation pathways, is discussed. Terminology is aligned with IUPAC recommendations to ensure conceptual clarity. Selected illustrative examples demonstrate the integration of theoretical principles with experimental practice in compound identification and analysis.