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pb070681 ☆ 2008-04-25 19:10 (6637 d 16:33 ago) Posting: # 1796 Views: 5,033 |
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My batch consist of 1) plasma blank 2) plasma blank+internal standard 3) calibration standards and .................. I observed interference at RT of Drug in plasma blank which is more than 20% of calibration standard 1 (LLOQ) but not observed in next sample ie plasma blank+internal standard is it necessary to repeat batch? pls provide referance if any? Regards Pramod |
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Ohlbe ★★★ France, 2008-04-30 03:03 (6633 d 08:40 ago) @ pb070681 Posting: # 1809 Views: 4,095 |
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Dear Pramod, What does your SOP say  ?IMHO the main goal of the plasma blank is to make sure that you have no interference at the retention time of your internal standard. I would rather interpret interferences at the RT of the analyte in the Blank+IS. Interference in the blanks is not part of the batch acceptance criteria in the The question you may get if you have a significant peak in the blank, but not in the blank+IS, is: where does this peak come from ? Could it be a contamination during sample processing (what sample preparation method are you using ?), or carry-over (what did you inject before your blank ?) ? Regards Ohlbe Edit: Link corrected for FDA’s new site. [Helmut] |
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pb070681 ☆ 2008-04-30 22:47 (6632 d 12:56 ago) @ Ohlbe Posting: # 1811 Views: 4,031 |
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Dear This might be contamination during sample processing because batch started with blank. so can i accept that batch or reject? |
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Ohlbe ★★★ France, 2008-05-01 00:40 (6632 d 11:03 ago) @ pb070681 Posting: # 1812 Views: 4,036 |
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Dear Pramod, If you have anything in your SOP, follow it. If not: personally I would accept the run, and record the justification for this acceptance in the raw data (no interference in Blank+IS). Then, write the SOP .If you suspect contamination during sample processing, you should also investigate how it may have happened and how to prevent it. Regards Ohlbe |
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vpardhasaradhi ☆ 2008-05-01 21:48 (6631 d 13:55 ago) @ Ohlbe Posting: # 1813 Views: 3,932 |
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Dear Ohlbe and Pramod, Do you think the batch construction is OK? Is it not better to construct the batch in the following way inorder to have additional check on the injector carryover in every batch. 1. Solvent blank 2. Calibration standards.... 3. Plasma blank 4. Plasma blank + Internal standard Regards, V.Pardhasaradhi |
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Jaime_R ★★ Barcelona, 2008-05-04 15:47 (6628 d 19:57 ago) @ Ohlbe Posting: # 1814 Views: 3,914 |
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Dear Ohlbe & Pramod! ❝ Interference in the blanks is not part of the batch acceptance criteria in ❝ the FDA guideline. Yes, and furthermore I do not understand the agitation... According to Edit: Link corrected for FDA’s new site. [Helmut] — Regards, Jaime |
Ing. Helmut Schütz