Hello,
I´m validating a new method and i´ve found that when i make two runs of two samples of the same concentration, the chromatograms are identical, but the area that sees the software are different. What i´d like to know is how could i integrate in a Shimadzu class AvP.5 in a not manual way,to get the same area.
Thanks

What happens when you run replicates of just one
of the samples?

Dear B.Buglio, i´ll tell you all my problems. I think i´m not goin to be able of get a good calibration curve..

I make two samples of the same concentration, i inject them and the chromatograms overlap well, are identical. the software sees differen

Dear B.Buglio, i´ll tell you all my problems. I think i´m not goin to be able of get a good calibration curve..

I make two samples of the same concentration, i inject them and the chromatograms overlap well, are identical. the software sees different areas.And i´ve tried to analyze it on my own, but it´s not a good method, i think i´m going to get more irreproducibility.

When i replicate one sample of the same vial,area is always different; i thought it was explained for evaporation of AcN; when i replicate the same sample of different vials ,i have less problem.

I suspected it was caused by the autosampler, because i was injecting only 500nL, but i changed to 1000nL and it improved.

Now, i think the soft is not so good..Sometimes it doesn´t permit me to integrate;sometimes it doesn´t write into integration events and MIF tables.., but works as if had done it, so you cant delete the parameters...Do you have any idea?

Thanks for being so fast answering,
Balto

When it's a software problem, just ask your manufacturer!

How different are the areas? One would always expect slightly different results from a replicate injection. At a minimum, you should expect area count reporducibility (over 5-6 injection) of lower that 1% RSD.

Need to know:
1) ans to above: what is the % difference of the
replicates from a single vial

2) Are you truly injecting 0.5 uL? Can you
inject 5uL and tell us your precision?

We had a sporadic problem with Class-VP where peaks from replicate injections looked identical until you changed the display so the overlayed peaks filled the entire display screen. Then you could see that one of the peaks was smooth and "Gaussian" but the peak from the injection in question had a sudden change in peak amplitude sometime during the peak. That is, instead of a smooth increase or decrease in peak amplitude over time, there was a point where there was a sudden jump in amplitude. I can't remember what the "fix" was for this, if this is your problem let me know and I will try to look it up.