Nitrogen Phosphorus Detector (Npd); Selecting An Npd Jet - Agilent Technologies 7820A Service Manual

Nitrogen Phosphorus Detector (NPD)

Agilent 7820 GC Service
65
The NPD is a variation on the FID, in that the sample is burned
and the resulting ions are collected. However, the hydrogen/air
ratio is set to suppress carbon ionization and an alkali salt
enhances nitrogen and phosphorus ionization.

Selecting an NPD jet

Open the oven door and locate the column connection fitting at
the base of the detector. It will look like either a capillary
optimized fitting or an adaptable fitting.

If you have an application that tends to clog the jet, select a
jet with a wider tip id.

When using packed columns in high column-bleed
applications, the jet tends to clog with silicon dioxide.
For adaptable fittings, select one of the following from the table
below, "Jets for adaptable fittings".
Table 37 Jets for adaptable fittings
Figure Jet type
4 ID
1 Capillary with
extended jet
(recommended)
2 Capillary
Part number Jet tip id Length
G1534-80590 0.29 mm
(0.11
inch)
19244-80560 0.29 mm
(0.011
inch)
70.5
mm
61.5
mm