Chromatography Forum

I recently trained new operator on one of my reactors that has an online GC sampling. Last week the operator started getting strange data from one of the 2 TCDs in the GC. The normal chromatagraph would have 2 peaks (aside from the carrier gas), one for hydrogen and one for nitrogen.

For the last couple of days the GC has been giving us either of the following chromatographs:

1) Just the carrier gas. No H2/N2 signals, but otherwise the graph looks normal.

2) Straight baseline noise. No signal.

It seems to just jump between the two of these from one sample to the next.

My suspicion is that the TCD has failed, which is aggravating because I only replaced that a year ago. Anyways, anyone have any ideas?

The GC is an Inficon 3000 microgc (used to be agilents micro gc) and the column is a molsieve column with a plotU precolumn....or its plotu with molsieve precolumn, I get that mixed up.

It sounds like the sampling valve is blocked off and on and this may have burned out your TCD.

Just a guess.

best wishes,

Rod

i agreed with chromatographer but i m not doutful about ur detector. i think sample is not reaching the detector either due to the valves or columns. make sure that sample is passing through the detector properly please and then check ur detector. u can check ur detector resistance before replacing it. note ur oven temperature also check that is it giving the same behavier with calibration gas.

What is the manufacturer?

You need to measure the resistance of the filament leads and confirm flow through the exit port using a flow meter. The earlier posts are probably correct, but these tests would confirm what is wrong.