NPD – Nitrogen-Phosphorus Detector


  • Very selective to nitrogen and phosphorus
  • Detects down to 100ppb
  • Exceptionally rugged NPD bead
  • Similar in design to the FID
ECD – Electron Capture Detector
Basic Model

The Nitrogen Phosphorus Detector responds to nitrogen-phosphorus compounds about 100,000 times more strongly than normal hydrocarbons. Due to this high degree of selectivity, the NPD is commonly used to detect pesticides, herbicides, and drugs of abuse.

The SRI ceramic NPD bead is exceptionally rugged and long-lasting, offering service from 100 to 1000 hours, depending on operating conditions.

The is NPD similar in design to the FID, except that the hydrogen flow rate is reduced to about 3 ml/minute and an electrically heated thermionic bead (NPD bead) is positioned near the jet orifice. Molecules containing nitrogen or phosphorus exiting the column collide with the hot bead and undergo a catalytic surface chemical reaction. The resulting ions are attracted to a collector electrode, amplified, and output to the data system.

NPD/DELCD Combination Detector

The NPD/DELCD combination detector is ideal for pesticide screening. The NPD selectively responds to the organo-phosphorus pesticides, while the DELCD detects only the chlorinated species.

8690-0015 NPD detector

8690-2615 NPD/DELCD detector