Easy Ambient Sonic-Spray Ionization Mass Spectrometry Combined with Thin-Layer Chromatography

Abstract

On-spot detection and analyte characterization on thin-layer chromatography (TLC) plates is performed via ambient desorption/ionization and (tandem) mass spectrometry detection, that is, via easy ambient sonic spray ionization mass spectrometry (EASI-MS). As proof-of-principle cases, mixtures of semipolar nitrogenated compounds as well as pharmaceutical drugs and vegetable oils have been tested. The technique has also been applied to monitor a chemical reaction of synthetic importance. EASI is the simplest and gentlest ambient ionization technique currently available, assisted solely by N2 (or air). It uses no voltages, no electrical discharges; no UV or laser beams, and no high temperature and is most easily implemented in all API mass spectrometers. TLC is also the simplest, fastest, and most easily performed chromatographic technique. TLC plus EASI-MS therefore provide a simple and advantageous combination of chromatographic separation and sensitive detection of the TLC spots as well as on-spot MS or MS/MS characterization. The favorable characteristics of TLC-EASI-MS indicate advantageous applications in several areas such as drug and oil analysis, phytochemistry and synthetic chemistry, forensics via reliable counterfeit detection, and quality control.

Established and emerging atmospheric pressure surface sampling/ionization techniques for mass spectrometry

“…Confusingly, this same DeSSI technique is now also being called easy ambient sonic spray ionization (EASI) by at least one research group. 113,114 One can view the high voltage and nebulizing gas velocities in DESI and DeSSI as variable parameters that at one extreme (high voltage and low gas velocity) is the DESI source and at the other extreme (no voltage and high gas velocity) is DeSSI. However, one source creates unipolar spray droplets with significant ion current and the other a bipolar, near neutral plume.…”

Easy mass spectrometry for metabolomics and quality control of vegetable and animal fats

“…EASI has therefore the advantages of requiring no preseparation steps and no or little sample preparation, and its ionization softness often produces intact molecular species, which facilitates mixture analysis with less background noise from solvent ionization [1]. EASI-MS has been applied with success to the identification of components in commercial drug tablets [1], to quantify analytes on-line in environmental and body fluids using a membrane interface [3], to typify fabric softeners [4] and perfumes [5], and has been coupled to TLC [6] and then applied to biodiesel analysis [7].…”

Scanning electron microscopic imaging of surface effects in desorption and nano‐desorption electrospray ionization

“…To evaluate the influence of the external electrostatic fields on the formation of rivulets, we performed the same experiments with the identical DESI set-up but without the high voltage on the sprayer (this experimental arrangement is sometimes referred to as easy ambient sonic spray ionization, EASI [26,28] or desorption sonic spray ionization, DeSSI [27] ) and in a nano-DESI (also referred to as desorption nano-electrospray) arrangement, [29 -31] which uses nanospray capillary and high voltage but no nitrogen carrier gas. Figure 4 shows that the rivulets formed by DESI without high voltage on the sprayer (EASI) are also well arranged into the same bent shapes as with the high voltage present (Fig.…”