u/Strict-Television-82

Hi there Reddit,

I feel like this might be a dumb question but since my Agilent 7890A only has 2 inlets if I were to convert one of them to take SPME arrows, could I still do ASD/manual injections into it as well? If it is what things do I have to consider when I do a normal injection?

The other inlet would be taken up by the transfer line of an Agilent 7697 headspace sampler so unless it's pretty easy and safe to remove that for an injection I assume I can only really treat the SPME inlet as my only functional port.

If it helps the conversion kit I plan to use is the Restek 27362 1.5mm inlet.

Hello Reddit. I am getting a headspace unit somewhat soon (the Agilent 7697 model) for the lab and as I am new to hs chromatography, I wanted to know if there was anything I should look out for in terms of supplies, software, and/or general advice for using it and keeping it running? I'm sure the guys coming to install it will give me plenty of notes but I figured Id ask the community too.

Hello reddit, I noticed lately that my inlet liner wool has been capturing bits of septum. I also see it in my wash vials. Do you guys have any recommendations for how to not let this happen? I have a feeling its because of the needle itself, so if I need to get new ones I would like to get the right ones.

The septa i use are Restek #27090. The needles we use currently are a bit of an unknown, but they are either Agilent #5181-3353 or Restek #21228.

For injection method its 1uL draws with 1 wash before and 1 wash after the sample of EtOH/MeOH respectively at a fast injection of like, 300/6000 draw/dispense speed.

Hello there chromatography nerds. I wanted some feedback on the feasibility, usability, and general memery regarding the following:

- Is it worth the time and effort to run 2 columns into one MS outlet?

- If I choose to run 2 columns into the same outlet, what options do I have? I know there are like T-fittings but how good are they? Can I close the flow from one column and have the other open?

- What considerations need to be made with running 2 columns into the same MS?

- Is it at all possible to join 2 different polarity columns together into one? Like a 15m ZB-Waxplus and a 15m ZB-1 for example?

For further context I use an Agilent 7980A with a 5975C, and my columns are all the same size at 0.25x0.25x30m, and I run with HE. I want to run SPME on some samples, and I am hoping to make use of the GC having two inlets (one to do direct injection and SPME and the other for everything else) rather than just using the one inlet for everything.

Hello there,

I was wondering if anyone in the subreddit had any procedures on extracting compounds from things like propylene glycol or glycerine? I have tried using DCM and salt water for PG extractions to poor results (I think the instructions I was provided might just suck though).

The compounds of interest in the samples I am running have colluding peaks of with both solvents, so even just turning off the MS during these peaks means im leaving things out.

If you guys have any suggestions id love to hear them!

Equipment and current method:

Agilent 7890A and 5975C

ZB-Waxplus

1:100 split injection, 1uL injection amount with 2-4 second viscosity delay

Ti = 75 c, hold for 1.5min (solvent delay), 10c/min to 155, hold 1 min (ms is off during this time too), 10c/minute to 250

Edit: I just realized I do have access to a fumehood and a distillation set up, if this helps anyone with suggestions.