Chromatography Forum

Dear all,
I am new to RS analysis by headspace/GCFID. I would like to get your opnion about the carrier gas pressure for HS. Does this pressure should be higher than the column pressure? I used a column pressure of about 4 psi and carrier gas pressure for HS is 10.4 psi with a split ratio of 1:1. I got a good peak response with 10 ml HS vials. I wanted to check with 20 ml HS vials but i couldnt see the peak even i increased concentration. what are the typical carrier gas pressures for HS? please help?

thanks

Your pressure parameters should be serviceable over a wide range. Pressuring the vial at 10 psi is acceptable. I suspect that you may be having splitter issues with a split of 1:1.

Call your vendor. They are most familiar with your hardware. The USP test should be second nature for them and they will guide you through the analysis.

But for the record, what column, flow rate, amount of dead volume in your sample line, sample loop volume, or timed injection parameters are you using in your HS configuration?

best wishes,

ROdney George
consultant

thanks for reply. I figured out the problem was leak at the detector.
My head space vial pressurisation is 14.3psi
carrier gas pressurization is 10.8 psi
column flow is 4.4 ml/min
I set up 1:1 split ratio in the software, I connected the HS and measured the split flow it is showing at ~60 ml/min.
peak comes at ~8.00 min and reproducible. when i mentioned in the method, should i mention the split ration 1/1?

Absolutely.

Rodney George
consultant

I forgot to thank you for telling us the end of the story. Many who post asking for help never give that courtesy. Your manners are appreciated.

best wishes,

Rodney George

Thanks for reply