Baseline fluctuations after 5 injections

Discussions about GC and other "gas phase" separation techniques.

3 posts Page 1 of 1
Hello,

we have a Shimadzu GC equipped with a BID (barrier discharge ionization detector). We make manual injections with the following parameters:

Column: ShinCarbon 2m
Split injection with a split ratio of 4
Injector: 150 C
Flow control with a flow of 7mL/min (pressure 276.4kPa, linear velocity 30.3cm/s)

Oven temperature is constant 100C and detector is at 280C. The whole program takes 6 minutes and the injection medium is H2 in Ar.

The injection is made every 10 minutes and after let's say 5 injections the baseline starts to fluctuate. If I heat the oven to 200C then will come a big peak and things will go back to normal for some time.

I assume that not all of the gases are eluted through the column as long as there is no higher temperature. Would it help if I increase the column flow?

How can I solve this issue?

Thanks a lot in advance!
If baking it out removes the interference you may want to set up a run program where after the last peak of interest elutes isothermal you ramp the temperature up for a couple minutes (or long enough to clear the column of interferences). It will add a few minutes to the run in total but you shouldn't have to stop every 5 samples to do the clean step so in the long run it may increase the number of samples you can run per day.
The past is there to guide us into the future, not to dwell in.
Thanks a lot! That's what I thought would be a solution. I will give it a try and hopefully it will work.
3 posts Page 1 of 1

Who is online

In total there are 3 users online :: 2 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm

Users browsing this forum: benhutcherson, Google [Bot] and 1 guest

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry