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krishnamurthy ca ☆ 2008-09-06 10:30 (6500 d 03:21 ago) (edited on 2008-09-06 13:06) Posting: # 2325 Views: 4,292 |
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Dear all with regard to the Q3 mass of the deuterated working standards (Q1/Q3 masses in LCMS/MS) a) During Method validation, a deuterated working standard from one Supplier was used with one set of Q1/Q3 masses b) During the study, the same deuterated working standard from another Supplier was used. However, there was a difference of about 5 amu in the Q3 mass of this deuterated working standard even though the same LCMS/MS was used. The following are to be clarified: 1. Can mass vary for the same deuterated working standard if they are from different suppliers ? 2. Is it ok that the deuterated working standard is being quantified at different masses during MV and study? 3. Is some kind of partial validation required for the same? regards KMR -- Edit: Please don't use capital letters. [Jaime] |
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Ohlbe ★★★ France, 2008-09-06 18:57 (6499 d 18:54 ago) @ krishnamurthy ca Posting: # 2331 Views: 3,350 |
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Dear KMR, This can happen if the IS is not deuterated in the same position depending on the supplier. You follow the whole molecule in Q1, but only one fragment of it in Q3, after the analyte is broken in Q2. Depending on the position where the deuterium substitution was made, you may keep it on the fragment you follow in Q3, or it may be on the fragment you don't monitor. In your case I would suggest to perform at least a partial validation (at least one P&A batch, possibly IS stock solution stability and on-instrument stability). Regards Ohlbe |
Ing. Helmut Schütz