51
GCDetectors
NPD -Nitrogen/PhosphorusDetector
This chromatogramshows the analysis
of a10ppmmalathion sample.
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,
anddrugs of abuse.
• VerySelective toNitrogenandPhosphorus
• Detectsdown to100ppb
• Exceptionally ruggedNPDbead
• Similar indesign to theFID
The NPD is similar in design to the FID, except that the hydrogen low rate is reduced to about 3mL/
minute and an electrically heated thermionic bead (NPD bead) is positioned near the jet oriice. Nitrogen
or phosphorus containingmolecules exiting the column collide with the hot bead and undergo a catalytic
surface chemistry reaction. The resulting ions are attracted to a collector electrode, ampliied, and output
to thedata system.
NPDbead
TheSRIceramicNPDbead isexceptionally rugged
and long-lasting, offeringservice from100 to1000
hours, dependingonoperating conditions.
8690-0015
NPDdetector
8690-2615
NPD/DELCDcombinationdetector
