Matrix-assisted inlet ionization

Recently, another technique termed matrix-assisted inlet ionization (MAII) was described by Trimpin et al, which enables the generation of multiply charged... 

Figure 2.1 Mass spectrometric approach. Dl, direct inlet GC, gas chromatography HPLC, high performance liquid chromatography CZE, capillary zone electrophoresis El, electron ionization Cl, chemical ionization ESI, electrospray ionization DESI, desorption electrospray ionization APCI, atmospheric pressure chemical ionization MALDI, matrix assisted laser desorption ionization B, magnetic analyzer E, electrostatic analyzer...

A mass spectrometer analyzes ions that are created from molecules. The overall working scheme can be viewed as a combination of three major processes ionization, sorting, and detection. (a) The first step is introduction of sample into the instrument. Samples can be introduced as either a solid, liquid, or vapor into a vacuum chamber through an inlet. Depending on the type of inlet and ionization techniques used, the sample may already exist as preformed ions or it may be imiized in the ion source. Several ionization modes [1] are commercially available with electrospray ionization (ESI) [2] and matrix-assisted laser desorption/ionization (MALDl) [3, 4] being the most widely used nowadays. ESI uses an electrical field to produce a droplet spray the sample in this case is typically in a volatile solvent. Irrespective of the original... 

This relationship between the final state of the sample and MS instramerrtation is mainly a consequence of the type of sample inlet and ionization technique used in a particular mass spectrometer. Referring to Fig. 2.1, the analysis of intact cells by matrix-assisted laser desorption/ionization-MS (MALDI-MS), (JaskoUa and Karas 2011) one of the simplest approaches for microorganism analysis by MS, (Holland et al. 1996) requires the isolation of a pure microbial colony, which is then deposited directly onto the MALDl plate. The subsequerrt mass spectral profiles. 

ELDI is that samples can be presented to the inlet nozzle directly from the outside as compared to ESI or MALDI that require additional sanple preparation [46], ELDI has also been applied to the analysis of peptides and proteins [47] even from biological media [48], to detect chemicals on different surfaces [49], and of course, for conpound identification on TLC plates [50]. It has been found that addition of a matrix is beneficial for the laser desorption part of the method. This gave rise to matrix-assisted laser desorption electrospray ionization (MALDESI)... 

Numerous ionization techniques have been reported in the last century, which are applicable to modern mass spectrometry. Depending on the method of analyte introduction (e.g., direct inlet, GC, LC, or capillary electrophoresis different strategies have been employed including El, Cl, thermospray, particle beam, electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), fast-atom bombardment (FAB), matrix-assisted laser desorption ionization (MALDI), etc. In sports drug testing, only selected approaches have been applied to routine doping control analyses, which are outlined in the following. 

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