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Random interferance

Posted: Tue Apr 26, 2011 9:42 pm
by aydonat
Dear all,

I have a big random interferance problem :(:(:(

I'm developing olanzapine method by UPLC-MS/MS with olanzapine-d3 as internal standard. I have 4 runs with very good results but some runs with bad results because of big random interferences. :!:

At the same batch, 3 different extracted same blank sample values are 450,35000,48.
And the results of reinjection of these blank samples values remain unchanged.

And 9 out of 10 different blank sources have no interference. Matrix effect analyses were performed and %CV value is 10.


-extraction procedure: liquid-liquid sample preparation with tert-buthyl-methyl-ether
-column: sunfıre c18
-mobile phase: Acetonitrile:water:formic acid (50:50:0.1, v:v:v)
-reconstitue solution: mobile phase
-injection volume: 10 µl
-flow rate: 0.3 ml/min
-Analyzed by MS in the multiple reaction monitoring mode using the respective [M + H]+ ions, m/z 313/256 for olanzapine and m/z 316/256for the IS(olanzapine-d3).

And also, there is no ınterferance on mobile phase and methanol injections.

Also, same results were observed with different analysts and different days.

What do you suggest to us? :?:

Thank you all,
Hale

Re: Random interferance

Posted: Fri Apr 29, 2011 2:30 am
by bisnettrj2
Can you post a chromatogram/TIC of a "good" run and a run showing this "interference" you are talking about?