NPD startup problem

[Stepan]

Hi, I am new in NPD chromatography.

We bought used GC HP 5890 with dual FID and NPD detectors on it, and managed to start the instrument. FID works just fine. Meantime NPD gives baseline around 6-15 pA and does not respond on injection of nitro compounds. We are confident that gases are pure and have proper flow rates: H2-4mL/min, Air 100 mL/min, He (make up) – 20 mL/min. I am not familiar with a faulty NPD “symptomsâ€

[Mark]

The next step is tp replace the bead to make sure you have a good one. The detector is very sensitive to the bead condition.

Regards,
Mark

[Stepan]

The next step is tp replace the bead to make sure you have a good one. The detector is very sensitive to the bead condition.

Regards,
Mark

Thank you, I will definitely try the new bead. But generally speaking, is this possible to have a non-zero signal with “deadâ€

[Stepan]

We started it!!

The problem was in cracked gasket at the detector base. It was leaking. Thank you all for the help and my special thanks to Abe Sanoja from MLS technologies Inc.