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haydonat ☆ Turkey, 2011-04-23 12:52 (5539 d 07:12 ago) Posting: # 6937 Views: 4,065 |
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Dear all, I have a big problem :(:(:( I'm developing olanzapine method by UPLC-MS/MS with olanzapine-d3 as internal standard. I have a few runs with very good results but a lot of runs with bad results just for QC1 levels, because of big interferences. Although interference areas are too high, they do not effect QC2 levels and 9 out of 10 different blank sources have no interference. Matrix effect analyses were performed twice with different concentrations and %CV values are 15 and 16. In one of matrix effect analysis one set of blank sample has both olanzapine and olanzapine-d3 peaks each of 6 injections with different amounts (we expect to observe only olanzapine-d3, because internal standard stock solution was spiked in to tubes). Also, same results were observed with different analysts and different days. What do you suggest to us? Thank you all, Hale |
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haydonat ☆ Turkey, 2011-04-27 01:44 (5535 d 18:19 ago) @ haydonat Posting: # 6944 Views: 3,251 |
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Dear all, I have a big random interference 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: sunfire 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 interference 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 Edit: Post linked to similar thread. Please don't fork in the future. [Helmut] |
Ing. Helmut Schütz