Miniaturized mass spectrometry integrated with ambient ionization sources: a review of system-level advances and emerging analytical applications.

Miniaturized mass spectrometry (mini-MS), characterized by its compact size, rapid response, low power consumption, and capability for on-site analysis, is increasingly transforming MS from a laboratory-centered technique into a field-deployable analytical tool. However, a critical review that systematically links instrument miniaturization, ambient ionization, pretreatment design, and algorithm-assisted analysis from a system-level analytical perspective remains lacking. This review provides a systematic and critical overview of recent advances in mini-MS, with a particular focus on the performance enhancement achieved through its integration with ambient ionization technologies. Recent developments in instrument architecture, ionization strategies, sample pretreatment, and algorithm-assisted data processing are summarized from a system-level perspective. These integrated approaches have substantially improved analytical performance in terms of sensitivity, selectivity, and signal stability, supporting improved trace-analyte detection in complex matrices. Representative applications in food safety, public security and drug abuse monitoring, environmental emergency analysis, and selected point-of-care testing (POCT)-related scenarios are discussed to illustrate the practical capabilities and emerging engineering trends of mini-MS systems. Despite these advances, several challenges remain, including the trade-off between analytical resolution and portability, variability in ionization efficiency under complex matrix conditions, and the lack of cross-platform standardization and robust quantitative frameworks. Future progress will depend on the synergistic development of hardware integration, green and rapid pretreatment strategies, intelligent data-processing algorithms, and data interoperability infrastructures. These efforts are expected to advance mini-MS from rapid screening toward more reliable quantitative assessment and intelligent decision support, ultimately enabling standardized and trustworthy on-site mass spectrometric detection systems.