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e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 5:16 am
by Kasiban
Dear All,
When try to inject standard in same vial in 5 duplicate with Alliance e2695, we 've got %RSD of Area > 2.0% in every test method.
Anyone can help, what is wrong with my instrument?
Best regards,
Kasiban
Re: e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 8:14 am
by Bull76
Hi,
Have you purged the Injector and verified that there is no bubble in the syringe. Also have you done a compressiblity test?
Regards,
Bull76
Re: e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 1:12 pm
by Kasiban
Hi Bull76,
I did it both purge injector and compessibility check.
No sign of problem from air bubble.
System pressure is constant before inject, equilibrate time is good (more than 20times of column volume), but we still get repeatability problem!
Regards,
Kasiban
Re: e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 4:01 pm
by AA
Try using pre-slit septa, they can often help.
Re: e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 4:33 pm
by Kasiban
Hi AA,
I am using pre-slit vial.
Regards,
Kasiban
Re: e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 6:35 pm
by Bull76
Hi,
If the compressibility test passed. Then you need to check the syringe or even replace the syringe. Possibly need to check V2 for leakage or buffer build up.
Regards,
Bull76.
Re: e2695 and injection repeatability problem
Posted: Sun Apr 03, 2011 9:56 pm
by tom jupille
Also take a look at your injection volume vs. the volume of the installed. Laminar flow effects can affect precision when you get up above 50% or so of the loop volume.
Re: e2695 and injection repeatability problem
Posted: Mon Apr 04, 2011 7:14 am
by unmgvar
does the 5 replicates give a behavior of areas
going down
going up
"all over the place"
only the first one is too low
the last one is too low
i remember also a case that a non-centered needle in a alliance system, caused a rep problem.
Re: e2695 and injection repeatability problem
Posted: Mon Apr 04, 2011 7:20 pm
by ym3142
what is the concentration?
What is the peak area or S/N?
How long the method runs?
what is the diluent? 100% aqueous or 100% ACN?
How is your blank baseline? DO you see any interference? How is you peak integrate?
what is your injection volume? 1 uL or 200 uL?
What is loop size? 20 uL or 2000 uL?
Thanks for sharing
Re: e2695 and injection repeatability problem
Posted: Mon Apr 04, 2011 10:42 pm
by WillyOne
Not too much data to send an opinion...
Anyway check the inner diameter of the loop. I've suffered a lot using a 100 microliters very short but very wide.
Seems that eluent at certain flow values can't sweep up completely the analyte off the loop.
Perhaps you can try to change the loop for a narrower one.
Please excuse my english
Re: e2695 and injection repeatability problem
Posted: Tue Apr 05, 2011 3:00 am
by Renato
Have you tried to change the Seal Pack and Needle?
V3 valve could be the defective part too.
Renato