Chromatography Forum

Found peaks in hexane blanks

siloxanes, diethyl phthalate, and benzophenone

changed inlet liner, o-ring, septa, ALS syringe, vials the blanks are stored in, waste vials

Seeing the same peaks. Haven't checked gas yet. It could be time for a change?

Welcome to the forum.

If you stick around you will find that requests for help that include details of what you analysing, on what instrument, column and detector and under what conditions will get you to a solution faster than abbreviated text messages that do little more than announce that you have a problem.

Have you tried different batches and sources of hexane ?

Peter

If your machine is used to analyze dirty samples for a while, you may need to scrub/clean the chamber where the liner stay, and also you may need to clean or change the vent trap.

BTW siloxanes may come from bleeding of the septa of the vials or the GC column.

Found peaks in hexane blanks

siloxanes, diethyl phthalate, and benzophenone

changed inlet liner, o-ring, septa, ALS syringe, vials the blanks are stored in, waste vials

Seeing the same peaks. Haven't checked gas yet. It could be time for a change?

Phthalates and benzophenone can come from personal care products too.
Has the hexane been in a container with a septum? Was it in contact with that septum? Did someone put their hands in the container with hand lotion on them before the hexane went into it? Lots of questions that only you can answer.
Try something other than the hexane you have been looking at. Preferably from a fresh bottle into new vials.

Make an injection with no penetration of the septume - just push the start button as though you are doing a manual injection. See what kind of garbage is hanging around in your instrument.

On inlet maintanance, be sure to check that there are no septum crumbs in the bottom of the inlet - a good source for sioxanes and plastic additives.

I haven't changed the gold seal yet, either. Could that be a factor?

Gold seal collects septum crumbs.