Nontargeted Screening Using Gas Chromatography–Atmospheric Pressure Ionization Mass Spectrometry: Recent Trends and Emerging Potential

Abstract

Gas chromatography–high-resolution mass spectrometry (GC–HRMS) is a powerful nontargeted screening technique that promises to accelerate the identification of environmental pollutants. Currently, most GC–HRMS instruments are equipped with electron ionization (EI), but atmospheric pressure ionization (API) ion sources have attracted renewed interest because: (i) collisional cooling at atmospheric pressure minimizes fragmentation, resulting in an increased yield of molecular ions for elemental composition determination and improved detection limits; (ii) a wide range of sophisticated tandem (ion mobility) mass spectrometers can be easily adapted for operation with GC–API; and (iii) the conditions of an atmospheric pressure ion source can promote structure diagnostic ion–molecule reactions that are otherwise difficult to perform using conventional GC–MS instrumentation. This literature review addresses the merits of GC–API for nontargeted screening while summarizing recent applications using various GC–API techniques. One perceived drawback of GC–API is the paucity of spectral libraries that can be used to guide structure elucidation. Herein, novel data acquisition, deconvolution and spectral prediction tools will be reviewed. With continued development, it is anticipated that API may eventually supplant EI as the de facto GC–MS ion source used to identify unknowns.

Benefits of Ion Mobility Separation in GC-APCI-HRMS Screening: From the Construction of a CCS Library to the Application to Real-World Samples

“…APCI is quite condition-dependent (flow conditions, source geometry, cone voltages, humidity, temperature, etc. ), which may have a negative impact on the reproducibility; moreover, the shortage of GC-APCI-HRMS-based spectra in available databases is also a limiting factor for a larger implementation of this technique. , A possible way to improve the comparability of spectra, as well as the identification power of the screening and the handling of complex mixtures is the coupling of GC-APCI with ion mobility and HRMS. , …”

First Novel Workflow for Semiquantification of Emerging Contaminants in Environmental Samples Analyzed by Gas Chromatography–Atmospheric Pressure Chemical Ionization–Quadrupole Time of Flight–Mass Spectrometry

“…The identification of nonpolar and volatile substances is not as easy as other soft ionization sources due to the complex MS1 and MS/MS fragmentation patterns of precursor ions. The GC-HRMS technique with soft ionization methods such as atmospheric pressure chemical ionization (APCI) could also provide valuable information such as identification of less LC amendable compounds and also compounds that are not ionizable in ESI. , For instance, it has been discovered that the full characterization of chlorinated paraffin mixtures can be achieved easily via the GC-APCI-MS technique in contrast to other techniques …”

Portable Digital Linear Ion Trap Mass Spectrometer Based on Separate-Region Corona Discharge Ionization Source for On-Site Rapid Detection of Illegal Drugs

“…Corona discharge ionization source has been widely used as a type of atmospheric pressure chemical ionization (APCI) [ 24 , 25 , 26 , 27 , 28 ], which is essentially an ion-molecule reaction in the gas phase. Therefore, the sample introduction method needs to turn the target analyte into the gas-phase.…”