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