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Charged Aerosol Detectors

Corona Veo and Corona Veo RS

Operating Instructions Page 17

2.3 Operating Principle

The operating principle of the detector is based on charged aerosol detection. In charged

aerosol detection, the detector measures charge that is imparted to dried particles that are

formed from an ultra-fine aerosol of the analyte. The measured charged is proportional to

the amount of analyte in the sample.

Fig. 1: Schematic drawing of the operating principle

No. Description No. Description

1 Mobile phase and analyte from column 6 Evaporation tube

2 Nebulizer 7 Mixing chamber

3 Gas inlet 8 Ion jet inlet

4 Spray chamber 9 Ion trap

5 Through drain pump to waste 10 Electrometer

The mobile phase with the analyte elutes from the column (no. 1) and is introduced into the

nebulizer (no. 2). Pressurized gas (no. 3) is introduced that has been passed through the

integrated gas filter. In the spray chamber (no. 4), the mobile phase with the analyte is

nebulized into an aerosol with the help of the pressurized gas. Large aerosol droplets are

removed from the detector by the drain pump (no. 5).

The resulting fine aerosol droplets pass through the evaporation tube (no. 6) that removes the

solvent and more volatile components. The remaining dried particles enter into the mixing

chamber (no. 7). The dried particles collide with a stream of ionized gas (no. 8) formed when

nitrogen passes over a corona wire. This leads to a diffusional charging of the aerosol

particles. The larger the particle, the higher is the level of charge that can be carried. The

particles that carry the charged nitrogen pass through an ion trap (no. 9).

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