Electrospray ionization mass description

This review provides an up-to-date overview of the application of analytical procedures based on MS for the characterization of organic natural materials in archaeological and historical objects. Applications that feature the use of gas chromatography/mass spectrometry (GC/MS), Py-GC/MS, high performance liquid chromatography combined with mass spectrometry (HPLC/MS), and direct MS analysis such as matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), electrospray ionization mass spectrometry (ESI-MS), and direct exposure mass spectrometry (DE-MS) are sununarized to highlight the different information provided by each of the various analytical approaches. Case studies and examples are also presented and include a description of the molecular markers and of the molecular profiles that are used to identify the original materials. 

The focus of this chapter is on the application of AutoDROP toward structure validation of every member of a substituted 4-phenylbenzopyrans library 1. The results of the NMR interpretation are compared with electrospray-ionization mass spectrometry (ESIMS) and HPLC analysis. A detailed description of... 

The term nebulizer is used generally as a description for any spraying device, such as the hair spray mentioned above. It is normally applied to any means of forming an aerosol spray in which a volume of liquid is broken into a mist of vapor and small droplets and possibly even solid matter. There is a variety of nebulizer designs for transporting a solution of analyte in droplet form to a plasma torch in ICP/MS and to the inlet/ionization sources used in electrospray and mass spectrometry (ES/MS) and atmospheric-pressure chemical ionization and mass spectrometry (APCI/MS). 

A detailed description of sources used in atmospheric pressure ionization by electrospray or chemical ionization has been compiled.2 Atmospheric pressure has been used in a wide array of applications with electron impact, chemical ionization, pressure spray ionization (ionization when the electrode is below the threshold for corona discharge), electrospray ionization, and sonic spray ionization.3 Interferences potentially include overlap of ions of about the same mass-charge ratio, mobile-phase components, formation of adducts such as alkali metal ions, and suppression of ionization by substances more easily ionized than the analyte.4 A number of applications of mass spectroscopy are given in subsequent chapters. However, this section will serve as a brief synopsis, focusing on key techniques. 

Since 2000, a myriad of LC-MS techniques have been reported to detect an array of NMBAs. These methods are valuable because they are generally more sensitive and more practical because they can measure a number of NMBAs simultaneously. Likewise, pharmacokinetic studies of neuromuscular blockers require low detection limits (sensitive chromatographic techniques such as tandem mass spectrometry with electrospray ionization combined with liquid chromatographic separation (LC-ESI-MS-MS) are better suited for these types of clinical applications.Brief descriptions of representative LC-MS methods follow. 

This section will cover the two most popular ionization techniques for analyzing proteins by mass spectrometry electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI). A brief description of five common mass spectrometers that have been coupled to these ion sources will follow. 

Currently, there are at least three ionization techniques routinely used in IMS (1) secondary ion mass spectrometry (SIMS), (2) matrix-assisted laser desorption ionization (MALDI), and (3) desorption electrospray ionization (DESI). Each of these ion sources has their own advantages and drawbacks thus, they are usually selected in the context of the imaged sample. In the following text, we provide a concise description of these devices. 

For a description of commercially available spectrometers designed specifically for electrospray ionization, see L, Vorees. Anal. Chem.. 1994, 66. -i81,A, For spectrometers combining electrospray with TOF mass analvz-ers, see C. M. Henr, Anal. Chem.. 1999,197a,... 

Mass spectrometry (MS) in its various forms, and with various procedures for vaporization and ionization, contributes to the identification and characterization of complex species by their isotopomer pattern of the intact ions (usually cation) and by their fragmentation pattern. Upon ionization by the rough electron impact (El) the molecular peak often does not appear, in contrast to the more gentle field desorption (FD) or fast-atom bombardment (FAB) techniques. An even more gentle way is provided by the electrospray (ES) method, which allows all ionic species (optionally cationic or anionic) present in solution to be detected. Descriptions of ESMS and its application to selected problems are published 45-47 also a representative application of this method in a study of phosphine-mercury complexes in solution is reported.48... 

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