Atmospheric Pressure Chemical Ionization (APCI) is an ionization method that uses ion-molecule reactions to ionize samples, facilitated by a nebulization process and corona discharge. This method is beneficial for less-polar compounds and provides an excellent interface for liquid chromatography-mass spectrometry (LC/MS). However, APCI is sensitive to contaminants and has relatively low ion currents and complex hardware requirements.

1. Atmospheric Pressure
Chemical Ionization
(APCI).
PRESENTED BY : VISHAL THAKUR
M.PHARM SEM.I
Dr. L.H.Hiranandani College Of pharmacy ,
Ulhasnagar.Maharashtra

2. 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.

3. 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.

4. APCI Diagram

5. 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.

6. 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

7. Benefits :
Excellent LC/MS interface
Good for less-polar compounds
Compatible with MS/MS methods
Mass range :
 Low-moderate Typically less than 2000 D.

8. Limitations :
Very sensitive to contaminants such as alkali metals
or basic compounds .
 Relatively low ion currents.
 Relatively complex hardware compared to other ion
sources.

9. REFERENCE
1.Http://Imaisd.Usc.Es/Riaidt/Masas/Imagenes/Ap
ci1.Jpg
2. Hoffman, Edmond, and Vincent Stroobant. Mass
Spectrometry: Principles and Applications. Great
Britain: JohnWiley & Sons Ltd., 2007
3.http://www.spectroscopynow.com/Spy/basehtml/
SpyH/1,1181,4-0-0-0-0-home-0-0,00.html

10. THANK YOU