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DESI is a combination of popular techniques, such as, electrospray ionization and surface desorption techniques. Electrospray ionization with mass spectrometry was reported by Malcolm Dole in 1968, [8] but John Bennett Fenn was awarded a nobel prize in chemistry for the development of ESI-MS in the late 1980s. [9]
Extractive electrospray ionization is a spray-type, ambient ionization method that uses two merged sprays, one of which is generated by electrospray. [ 49 ] Laser-based electrospray-based ambient ionization is a two-step process in which a pulsed laser is used to desorb or ablate material from a sample and the plume of material interacts with ...
DESI and DART are considered as pioneer techniques in the field of ambient ionization, [4] since they operate in the open laboratory environment and do not require sample pretreatment. [ 5 ] [ 6 ] In contrast to the liquid spray used by DESI, the ionizing gas from the DART ion source contains a dry stream containing excited state species.
Nanospray desorption electrospray ionization (nano-DESI) is an ambient pressure ionization technique used in mass spectrometry (MS) for chemical analysis of organic molecules. [1] In this technique, analytes are desorbed into a liquid bridge formed between two capillaries and the sampling surface. [ 2 ]
Ambient ionization techniques are attractive for many samples for their high tolerance to complex mixtures and for fast testing. EESI has been employed for the rapid characterization of living objects, [ 10 ] native proteins , [ 11 ] and metabolic biomarkers .
In 2001, more than 1700 papers on proteomics were published, many using electrospray ionization. [9] Electrospray ionization provides a way to get accurate information about the mass of a large molecule very quickly, even when it is in a mixture of other molecules. [10] The liquid sample is introduced into an electrospray source (at atmospheric ...
Schematic diagram of ion trap mass spectrometer with an electrospray ionization (ESI) source and Paul ion trap. A Paul trap is a type of quadrupole ion trap that uses static direct current (DC) and radio frequency (RF) oscillating electric fields to trap ions. Paul traps are commonly used as components of a mass spectrometer.
The energy of the electron beam is typically 70 electronvolts and the ionization process typically produces extensive fragmentation of the chemical bonds of the molecule. Due to the high vacuum pressure in the ionization chamber, the mean free path of molecules are varying from 10 cm to 1 km and then the fragmentations are unimolecular processes.