Problem with PPU column

Hello Nabin ,

I am rather unfamiliar with the Micro GCs, but just looking at the two chromatograms, it looks the signal goes from 3.3 mV approximatively to 0 mV, then stays there. It is hard to tell on the original chromatogram where the baseline is at, but if you can zoom in, I'd be curious to see. Is it at 3.3, is it at 0?

What type of detector are you using? Only asking because I am assuming it could be a detector problem, not a column problem.

Hopefully someone with knowledge on Micro GCs will be able to provide a better answer on this.

Hi CMZainea

The detector is microTCD. Both the signals are from running ambient air sample with exactly the same settings. Now, there is slight response in the beginning and then it goes down to zero as you noted. When it was functioning normally, there was a composite peak (everything in the air) at 0.348s followed by a CO2 peak at 0.401s. These signals are completely missing now.

I don't have an extensive knowledge on GC systems in general. I have used it only occasionally. So, I was wondering if someone has some insights into this problem.

Hello Nabin ,

Thank you for the information. I will inquire and see what I can do to assist on this.

Out of curiosity, have you recently changed the data rate recently? I don't think it's the (main) cause of the problem, but always good to check.

Hi Nabin,

The 2nd channel is PPU backflush channel, according to the chromatogram, I suspect the pre-column is broken. All components are vented from broken pre-column but not entering the analytical column. You have to reach out to Agilent local service team to replace the module.

Hope it can help.

Hi Robert 

Thank you. Yes, that might be the case. It also came to my mind last evening that sample may have vented/leaked without passing through the column.

Thank you. The sampling frequency I have used is 100 Hz.