Preventive Maintenance

Nitrogen-phosphorus detector (NPD)

is best to have a new jet on hand to exchange if a damaged jet is suspected.

Nitrogen-phosphorus detector (NPD)

In addition to the detector itself, other systems associated with the detector may also require routine maintenance.

WARNING Nitrogen•phosphorusdetectors use H2 gas as fuel. If H2 flow is on, and no column is connected to the detector inlet fitting, H2 gas can flow into the oven and create an explosion hazard. Inlet fittings must have either a column or a cap connected at all times.

Cleaning

Both the jet and the detector base require occasional cleaning to remove deposits (usually consisting of white silica from column bleed). Such deposits reduce sensitivity and cause chromatographic noise and spikes.

Figure 8-14

Flame Ionization and Nitrogen-Phosphorus Detectors

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