Technical data

22 Agilent 6200 Series TOF and 6500 Series Q-TOF LC/MS System Concepts Guide

1Overview

Atmospheric pressure chemical ionization (APCI)

APCI is a gas-phase chemical ionization process. The APCI

technique passes LC eluent through a nebulizing needle, which

creates a fine spray. The spray is passed through a heated

ceramic tube, where the droplets are fully vaporized (Figure 4).

The resulting gas/vapor mixture is then passed over a corona

discharge needle, where the solvent vapor is ionized to create

reagent gas ions. These ions in turn ionize the sample molecules

via a chemical ionization process. The sample ions are then

introduced into the capillary.

APCI requires that the analyte be in the gas phase for ionization

to occur. To vaporize the solvent and analyte, the APCI source is

typically operated at vaporizer temperatures of 400 to 500°C.

Figure 4 Atmospheric pressure chemical ionization (APCI) source

nebulizer (sprayer)

HPLC inlet

vaporizer

(heater)

drying gas

capillary

corona

discharge

needle