Detector Systems

Nitrogen-phosphorus detector (NPD)

Nitrogen-phosphorus detector (NPD)

Figure 7-3

NPD Collector

Assembly

Air Inlet

NPD Collector

Active Element

Jet

H2 Inlet

Nitrogen-Phosphorus Detector (NPD)

The nitrogen•phosphorusdetector uses a jet and collector similar to the FID; however, the collector contains a small alumina cylinder coated with a rubidium salt (the active element) which is heated electrically. In the presence of this thermionic source, nitrogen•and phosphorus•containing organic molecules are efficiently ionized. Ions are collected, and the resulting current is measured.

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