From Columns to Clouds: Emerging Interfaces and Ion Sources for Coupling Analytical Separations With Mass Spectrometry

Although mass spectrometry (MS) is a powerful analytical technique, it is vulnerable to matrix interference, and it does not distinguish ions with the same m/z (isobaric interference). Therefore, for the past few decades, numerous efforts have been made to enable coupling separation systems with MS. Apart from a set of mainstream hyphenation approaches (such as those using inductively coupled plasma ionization, electron ionization, and electrospray ionization), a number of less conventional ways to couple separation systems with MS have been devised. Extraordinary methods for coupling gas chromatography, liquid chromatography, capillary electrophoresis, thin-layer chromatography, supercritical fluid chromatography, and other unconventional interfaces and ion sources have been disclosed in the literature. Some of these techniques extend the analyte coverage of traditional hyphenated techniques by enabling the detection of less polar compounds. Others speed up analysis or decrease the cost. Another notable trend is the implementation of the so-called ambient ionization techniques for coupling separations with MS.