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vajra123 ☆ India, 2010-09-15 13:06 (5765 d 11:04 ago) Posting: # 5910 Views: 4,960 |
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Hi Group members, This is regarding the integration of the internal standard when one IS is used in the simultaneous estimation of the drugs. For example i have a method Analyte A and B, for both the internal standard is X. the quantification method is Lc/ms. When integrating a batch whether i have to use only integration parameter for the IS in the analyte A and analyte B or I can apply separate integration parameters for the IS in analyte A and analyte B respectively. please correct me if wrong. Regards, Vajra. — Vajra |
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Ohlbe ★★★ France, 2010-09-15 14:02 (5765 d 10:08 ago) @ vajra123 Posting: # 5911 Views: 4,153 |
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Dear Vajra, ❝ When integrating a batch whether i have to use only integration parameter for the IS in the analyte A and analyte B or I can apply separate integration parameters for the IS in analyte A and analyte B respectively. You can have different integration parameters for each peak (A, B and IS), and optimise them so that you get a correct integration for each. But why would you want to use different integration parameters for IS when quantifying A and B ? Either your IS peak is correctly integrated and there is no reason to repeat the work and re-integrate differently, or it is not correctly integrated and you need to change for both. Using separate integration parameters may arise suspicion that you are doing this to tweak the data to get the results you want, or to make failing runs pass. Regards Ohlbe — Regards Ohlbe |
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Helmut ★★★   Vienna, Austria, 2010-09-15 15:32 (5765 d 08:39 ago) @ Ohlbe Posting: # 5912 Views: 4,149 |
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Dear Ohlbe & Vajra, ❝ You can have different integration parameters for each peak (A, B and IS), and optimise them so that you get a correct integration for each. But why would you want to use different integration parameters for IS when quantifying A and B ? Hhm, cough... IMHO you answered the question already in your first sentence. It's natural (especially if with large differences in k' values are concerned) that a common setting of integration parameters will be suboptimal. In all data systems I know of it's not possible to change the bundling rate (which would be desirable), but other parameters (like peak width, slope, threshold, etc.) are. In other words a common setting for the entire chromatogram is easy to handle, but scientifically not justified. ❝ Using separate integration parameters may arise suspicion that you are doing this to tweak the data to get the results you want, or to make failing runs pass. Well, right (according to regulator's paranoia). But at least if different settings are part of the method specification and validated, such a question should not arise - or at least be answered easily. I agree that it does not make sense to apply different settings for peaks in a particular batch (if a common setting was validated). — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png) Helmut Schütz ![[image]](https://static.bebac.at/img/CC by.png) The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
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Ohlbe ★★★ France, 2010-09-15 15:51 (5765 d 08:19 ago) @ Helmut Posting: # 5913 Views: 4,089 |
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Dear Helmut, ❝ It's natural (especially if with large differences in k' values are concerned) that a common setting of integration parameters will be suboptimal. Fully agreed. That's why different integration parameters are usually needed for A, B and IS. But if you have integrated the IS one way when quantifying A, why integrate the very same peak differently when quantifying B ? ❝ But at least if different settings are part of the method specification and validated, such a question should not arise - or at least be answered easily. True. But integration settings may need to be fine-tuned batch to batch, and this would make the job a bit more difficult considering regulators' paranoia when it comes to chromatogram integrations. Regards Ohlbe — Regards Ohlbe |
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Helmut ★★★ Vienna, Austria, 2010-09-15 16:05 (5765 d 08:06 ago) @ Ohlbe Posting: # 5914 Views: 4,156 |
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Dear Ohlbe! ❝ [...] But if you have integrated the IS one way when quantifying A, why integrate the very same peak differently when quantifying B ? Oh, now I understand Vajra's post! Does not make sense - shouldn't do that. ❝ [...] integration settings may need to be fine-tuned batch to batch, and this would make the job a bit more difficult considering regulators' paranoia when it comes to chromatogram integrations.  — Dif-tor heh smusma 🖖🏼 Довге життя Україна! Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
Ing. Helmut Schütz