Different ion mobility‐mass spectrometry coupling techniques to promote metabolomics

Abstract

Metabolomics has become increasingly popular in recent years for many applications ranging from clinical diagnosis, human health to biotechnological questioning. Despite technological advances, metabolomic studies are still currently limited by the difficulty of identifying all metabolites, a class of compounds with great chemical diversity. Although lengthy chromatographic analyses are often used to obtain comprehensive data, many isobar and isomer metabolites still remain unresolved, which is a critical point for the compound identification. Currently, ion mobility spectrometry is being explored in metabolomics as a way to improve metabolome coverage, analysis throughput and isomer separation. In this review, all the steps of a typical workflow for untargeted metabolomics are discussed considering the use of an ion mobility instrument. An overview of metabolomics is first presented followed by a brief description of ion mobility instrumentation. The ion mobility potential for complex mixture analysis is discussed regarding its coupling with a mass spectrometer alone, providing gasphase separation before mass analysis as well as its combination with different separation platforms (conventional hyphenation but also multidimensional ion mobility couplings), offering multidimensional separation. Various instrumental and analytical conditions for improving the ion mobility separation are also described. Finally, data mining, including software packages and visualization approaches, as well as the construction of ion mobility databases for the metabolite identification are examined.

Six Decades of Research on Human Fetal Gonadal Steroids

“…An advantage of LC-ESI-qQTOF instrumentations compared to Orbitrap instruments is the ability to associate ion mobility (IMS-MS) to mass measurements for structure characterisation. Ion mobility in MS is an analytical method used to separate molecules and particularly isomers by measuring the mobility of ions through a collisional gas by using drift tube (DTIMS), travelling wave (TWIMS), trapped (TIMS), field asymmetric waveforms (FAIMS), and cyclic ion mobilities [116].…”

Lipid analysis by ion mobility spectrometry combined with mass spectrometry: A brief update with a perspective on applications in the clinical laboratory

“…CCS in an IMS device is calculated via the Mason-Schamp equation [3] , which utilizes the mobility ( K ) parameter. The K parameter of a given ion correlates with its movement through a buffer gas at a velocity ( v d ) under the influence of an electric field ( E ) by the equation K = v d / E [3] , [4] , [5] .…”

“…Currently, there are several different commercially available types of IMS devices that are coupled to MS. These include drift tube ion mobility spectrometry (DTIMS), traveling wave ion mobility spectrometry (TWIMS), structures for lossless ion manipulations (SLIM), field asymmetric waveform ion mobility spectrometry (FAIMS), and trapped ion mobility spectrometry (TIMS) [4] , [5] , [8] , [9] ( Fig. 2 ).…”

“…DTIMS measures how long it takes for a given ion to travel through a stationary buffer gas within a uniform electric field drift tube and provides a direct calculation of CCS via measurement of the drift time which is connected to the mobility ( K ). Smaller ions collide less frequently with the buffer gas and, therefore, travel faster than larger ions through the device [4] , [8] , [10] . TWIMS does not utilize a uniform electric field, instead it uses a sequence of symmetric potential traveling waves that electrostatically draw ions through the stationary drift gas.…”

Metabolomics in Retinal Diseases: An Update

“…For example, to circumvent peak overlapping (e.g., isomers) and increase metabolome coverage, using ion shape and size as an additional dimension of separation has been achieved by ion mobility spectrometry coupled with mass spectrometry (IMS-MS). IMS-MS, along with front-end separation technologies, such as LC and GC, can provide multi-dimensional separation, thus improving peak capacity and separation efficiency [16]. In studies involving direct infusion into MS, several ion sources, such as electrospray ionization (ESI), matrix-assisted laser desorption/ionization (MALDI), or desorption electrospray ioniza-tion (DESI), have been used for maximizing sample throughput.…”