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Roberto ☆ Italy, 2015-02-19 17:51 (3748 d 05:17 ago) Posting: # 14461 Views: 6,787 |
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Dear colleagues, I have a question to submit to you. Due to a failure of an analytical run it’s possible to repeat an entire run using the fraction stored in the refrigerator of all the samples already extracted? The failure was due to an instrumental problem highlighted by an internal investigation as foreseen by a specific SOP, and the samples to be reuse have a stability in the refrigerator that allows their use, as supported by the specific study. Thanks in advance Roberto |
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Ohlbe ★★★ France, 2015-02-19 19:48 (3748 d 03:21 ago) @ Roberto Posting: # 14463 Views: 5,702 |
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Dear Roberto, ❝ The failure was due to an instrumental problem highlighted by an internal investigation as foreseen by a specific SOP If indeed you have clear evidence (not just an assumption) that there was an instrument malfunction, you should be able to re-inject the extracts. — Regards Ohlbe |
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Dr_Dan ★★ Germany, 2015-02-20 09:29 (3747 d 13:40 ago) @ Ohlbe Posting: # 14468 Views: 5,670 |
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Dear Ohlbe ❝ If indeed you have clear evidence (not just an assumption) that there was an instrument malfunction, you should be able to re-inject the extracts. IMHO you should also consider if the internal investigation took place before or after statistical evaluation and thus was triggered by an unexpected or unfavorable study result. Kind regards Dr_Dan — Kind regards and have a nice day Dr_Dan |
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Ohlbe ★★★ France, 2015-02-20 10:39 (3747 d 12:29 ago) @ Dr_Dan Posting: # 14469 Views: 5,647 |
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Dear Dan, ❝ IMHO you should also consider if the internal investigation took place before or after statistical evaluation and thus was triggered by an unexpected or unfavorable study result. Agreed. I interpreted Roberto's reference to failed runs as meaning that the calibration and / or QCs failed, or that significant interferences were seen, or this kind of things. Considering also that the data available on extracts stability are usually limited to 72 h max, I also assumed that the internal investigation took place before statistical evaluation. To me it would not be acceptable to run the stats, see that the study fails, go back to the chromatograms, say "oh we had a problem with this run" and re-analyse the samples. Whether this would be done by re-injecting the extracts or by completely re-processing them would make no difference. — Regards Ohlbe |
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nobody nothing 2015-02-20 12:58 (3747 d 10:10 ago) @ Roberto Posting: # 14470 Views: 5,720 |
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Hi! Which SOP? What kind of technical problem? Every analytical re-run is fishy, as long as the first try is fully evaluable. — Kindest regards, nobody |
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Roberto ☆ Italy, 2015-02-25 10:57 (3742 d 12:11 ago) @ nobody Posting: # 14505 Views: 5,480 |
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Dear colleagues Thank you for your opinions and, especially Ohlbe which, I think has got the gist the real problem. No stats was made prior. We are only a laboratory of analytical determination and the PK statistics are made by the Sponsor. The instrument (LC-MS-MS) at about halfway began to respond abnormally and only in the morning we could realize what happened and an investigation was started. The consequence was the QC failed in the second part of the run (when the instrumental response is changed), and consequently the entire run failed and should be repeated. Having studied the stability of the samples after extraction, it was decided to reuse all them (CS, QS, unknown samples stored in the refrigerator) to repeat the run. IMHO we decided correctly. Yours truly Roberto |
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