Question

Briefly explain the difference between CI, MALDI, and ESI. What type of molecule would you use for each of these techniques?

Answer 1

Chemical ionization :

In the ionization method a reagent such as methane, isobutane or ammonia is introduced into high presure (0.1 to n1 torr) and ionized by electron bombardment. The primary ion produces undergo ion-molecule collision to form stable population of secondary reagents ions. SMALL MOLECULE ANALYSIS CAN BE DONE BY THIS METHOD..

MALDI:

In MALDI sample to be analysed is dissolved or disperded in a matrix and placed in the path of high energy beam of ions. neutral atom of high density of photons. The colloison of these ions/atoms/photons with sample ionize some of the sample molecules an eject them from surfaces.

LARGER MOLECULE LIKE PROTEN CAN BE STUDIED BY THIS METHOD. POLYATOMIC CLUSTER LIKE SILVER CLUSTER AND GOLD CLUSTER CAN BE ANALYSED METHODS.

ESI ;

An even more useful technique for studying high molecular weight biomolecules and other labile or nonvolatile compounds is electrospray ionizations.Negative ions may be also fors in ESI.

LARGER BIOMOLECULE, SMALL MOLECULE CAN BE ANALYZED METHOD .