ESI mass spectra exhibit a significantly higher level of complexity compared to EI mass spectra. This complexity arises from ESI's capability to produce high-resolution spectra under a wide range of instrumental conditions, catering to a diverse array of analytes. As a result, the process of compound identification using ESI mass spectra is markedly different from that employed with EI mass spectra. Specifically, unlike EI-based identification, ESI-based identification requires a series of preprocessing steps to accurately calculate similarity scores between mass spectra. These steps include the application of a weight factor transformation to account for differences in ionization efficiencies, centroiding of peaks to simplify the spectra, removal of background noise to enhance signal clarity, matching peaks across spectra for comparison, transforming low-entropy spectra to reduce data redundancy, and normalizing the spectra to allow for the computation of Shannon and Tsallis entropy. Each of these steps is critical for the reliable identification of compounds in complex mixtures, underscoring the sophistication and versatility of ESI mass spectrometry.