Random interferance

[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, vv)
-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

[bisnettrj2]

Can you post a chromatogram/TIC of a "good" run and a run showing this "interference" you are talking about?