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Atmospheric Pressure Chemical Ionization
(APCI).
PRESENTED BY : VISHAL THAKURM.PHARM SEM.I
Dr. L.H.Hiranandani College Of pharmacy ,Ulhasnagar.Maharashtra
INTRODUCTION
This is an ionization method in which the sample is
ionized using an ion – molecule reaction with a
reactant ion. Sample solution is nebulized by the N2
nebulizer gas to form a spray as it enters the heater(at
about 400°C),and both sample and solvent molecules
are vaporized to a gaseous state. The solvent molecules
are ionized by the corona discharge, and stable reactant
ions are formed.
Protein transfer occurs between these reactant
ions and sample molecules (ion – molecule
reaction), and the sample molecules either add
or lose protons to become ions. This ion –
molecule reaction is known to occur in a
variety of patterns, such as protein shift
reactions, electrophilic addition reactions, etc.
APCI Diagram
The APCI process:
The sample is in a flowing stream of a carrier
liquid (or gas) and is nebulized at moderate
temperatures.
This stream is flowed past an ionizer which
ionizes the carrier gas/liquid.
The ionized stream acts as the primary reactant
ions, forming secondary ions with the analytes.
The ions are formed at AP in this process, and
are sent into the vaccuum
In the vaccuum, a free-jet expansion occurs to
form a Mach disk and strong adiabatic cooling
occurs.
Cooling promotes the stability of analyte ions
Benefits :
Excellent LC/MS interface
Good for less-polar compounds
Compatible with MS/MS methods
Mass range :
Low-moderate Typically less than 2000 D.
Limitations :
Very sensitive to contaminants such as alkali metals
or basic compounds .
Relatively low ion currents.
Relatively complex hardware compared to other ion
sources.
REFERENCE
1.Http://Imaisd.Usc.Es/Riaidt/Masas/Imagenes/
Apci1.Jpg
2. Hoffman, Edmond, and Vincent Stroobant. Mass
Spectrometry: Principles and Applications. Great
Britain: John Wiley & Sons Ltd., 2007
3.http://www.spectroscopynow.com/Spy/basehtml/
SpyH/1,1181,4-0-0-0-0-home-0-0,00.html
THANK YOU