We are currently experiencing problems on an PE Autosystem XL (non-PPC) with RSD's for repetitive injections of the same sample (test mix)
Running in split mode (25:1).
Currently getting 4-6% RSD with manual injection(in the past 1-2%).
We have tried replacing the septa, syringe, injection liner, column, carrier, detector assembly, detector applifier.
Currently contemplating replacing injector assembly.

Yes, we checked for leaks.

Suggestions, anybody.

Regards,

DTM

Have you closely monitored the split flow? Be sure and check that the mass flow controller is operating properly along with the molesieve filter. Changed style of split injector liner?

Monitored split flow with electronic flow meter. No appreciable change. We did change the style of liner from PE to an SGE focus liner (which made it worse 15% RSD)
We also repacked the charcoal trap on the split vent.

Dan

Hello DTM,

try another column position in the injector,
glass whool amount and position
liner inertness (deactivated or not)
injection deepness syringe

What is the solvent?

Darn, I was going to suggest SGE focus liner - When I started to use them my RSDs went from 3-5% down to 0.1 - 0.2%

hai
what is a focus liner and what physics behind it

thanks

Focus liners are made by SGE - Check their web site. I like them because the wool is held in place by a double taper, and the wool also appears to be installed more consistently from liner-to-liner than other brands of straight liners I've seen. I have also seen a slight loss of peak sharpness w/ the Focus liners relative to a straight wool-packed liner, but the reproducibility was more than worth it for me.

Does the data acquisition have anything to do with the RSD's. Has the software baselines, peak shapes...others changed? Is this the same analyst as the 1-2% RSD analyst. Same injection technique....? Puzzling?