Special Issue "Unconventional and Emerging Liquid Chromatography-Mass Spectrometry Techniques: Recent Developments and Applications"

Dear Colleagues,

It is universally known that liquid chromatography-mass spectrometry (LC-MS) techniques have entered all analytical laboratories, equaling or sometimes surpassing the well-established and consolidated GC-MS. The reason for this success is that no other analytical instrument combination can cover as many applications as LC-MS. There is no doubt that its popularity has grown exponentially with the advent of atmospheric pressure ionization (API) techniques and their ability to analyze high molecular weight molecules. Among the API techniques, an exceptional impulse to LC-MS came undoubtedly from electrospray Ionization (ESI) thanks to its great ionization efficiency and multicharged capability, allowing the analysis of macromolecules even with limited mass range analyzers.

Unfortunately, ESI suffers are limited by the ionization of non-polar compounds, characterized by non-uniform, compound-specific response, and plagued by ion suppression or enhancement effects (matrix effects). Based on these considerations, other ionization or interfacing techniques can coexist to compensate for some of the drawbacks of ESI. Sometimes, these complementary techniques are readily available on the market, such as atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI); in other cases, they are advanced prototypes such as electron ionization (EI)-based interfaces. APCI and APPI are useful to analyze slightly polar or non-polar compounds. EI can guarantee unparallel identification potential due to a rich fragmentation production, even with single stage or low-resolution analyzers, with no limitations related to molecule polarity, and scarcely affected by matrix effects. Recently, EI-based interfaces have been employed successfully in direct-MS, without chromatography or using the liquid mobile phase as a reagent gas to obtain positive chemical ionization (PCI) spectra.

The purpose of this Special Issue is to show the current LC-MS solutions proposed as an alternative to ESI, their advantages and new trends. Innovative studies on advances in the interfacing process are welcome: the submission of papers illustrating prototypes, new instrumental configurations, and direct-MS methods applied to environmental, clinical, homeland and food security, and other analytical fields, is encouraged. The role and use of these LC-MS solutions should certainly be pointed out.

Dr. Giorgio Famiglini
Guest Editor

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• LC–EI–MS
• LC–MS
• Electron ionization
• Matrix effects
• Electronic libraries
• Direct-MS
• LC–EI/CI–MS
• Environmental analysis
• Clinical analysis
• Food and homeland security
• Forensic analysis
• Field analysis