Chromatography Forum

Did you have yet experienced a loss of linearity response (tri or tetrachloroethylene, CHCL3, CCL4 and other chlorinated volatiles compounds, Internal standard calibration) with an high head column pressure ?
Is this possible ?
We operate with automated SPME in Headspace mode (20 ml vials filled with 15 ml sample/water and 3.5g of NaCL) and we inject @ 25psi head pressure with a 0.32mm column. Same results with different fibers (CAR/PDMS, DVB/CAR/PDMS, PDMS or DVB/PDMS). We have a liner of 0.75mm diameter and a Merlin septum.
We operate with an on-column injection.
All opinions are appreciated !!

Thank you a lot,

Regards,

Joe

Joe,

What detector?

Best regards.

We are using an ECD.

Thank you for your reply.

Joe

JoeJoe,

Perc and carbon tet are great ECD responders (probably the best!) ECD's are not all that linear to begin with relative to others like the FID. Is it just possible that you are exceeding the ability of the ECD? What happens if you cut the whole curve in half and do you have the same linearity problems with compounds like TCA or DCM? What make up are you using, P10 or nitrogen?

Best regards.