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najat ☆ 2009-10-08 20:51 (6101 d 10:38 ago) Posting: # 4324 Views: 3,443 |
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Dear Sir During a QA audit, we have encountered the following situation regarding accuracy calculations for the SCC and QCs. Where discrepancy between manual calculation and LC-MSMS generated software calculations printout (Waters API 3000) gave two different results, where: Case 1): Manual calculations using one decimal place for calculating accuracy gave a result at the LLOQ “SCC” of 20.00% accuracy (i.e LLOQ meets the acceptance criteria of <20.00%) Case 2): Automatic software calculations for accuracy gave a result at the LLOQ “SCC” of 20.50% accuracy (i.e LLOQ fails to meet acceptance criteria of <20.00%) Same applies with QC calculations. This was seen when the accuracy result is on the border-line of the limit The above-mentioned case was noted in 17 volunteers from 76 volunteers’ analysis. Kindly advice what action(s)/step(s) should be taken to solve this dilemma? And how do you solve such a discrepancy in results? And how would European authorities look at such a case? Appreciating your feedback Thank you and best regards  Najat |
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Ohlbe ★★★ France, 2009-10-09 00:49 (6101 d 06:41 ago) @ najat Posting: # 4325 Views: 2,763 |
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Dear Najat, ❝ Dear Sir We also have some Ladies on the forum, don't discourage them from answering ❝ LC-MSMS generated software calculations printout (Waters API 3000) Which software ? Waters' is Masslynx, API 3000 runs with Analyst. ❝ Where discrepancy between manual calculation and LC-MSMS generated software ❝ calculations printout (Waters API 3000) gave two different results, This may happen due to rounding. How many digits do you use for manual calculations ? Not just decimals (1.2 is one decimal but 2 digits, 123456.7 is still one decimal but 7 digits, 0,00005 is 5 decimals but 1 digit). If you use 3 digits for calculations and give the result with 4 digits, you'll get in trouble. The software will use more digits than what you get on the printout. ❝ Kindly advice what action(s)/step(s) should be taken to solve this ❝ dilemma? And how do you solve such a discrepancy in results? Try and get enough digits on the printout (or on screen)... In most software the user can define at least the number of decimals in the output. ❝ And how would European authorities look at such a case ? Assessors will probably not recalculate. Some inspectors might. Some definitely will. But these ones are supposed to know about rounding. And that's something you can at least try and explain. Regards Ohlbe — Regards Ohlbe |
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najat ☆ 2009-10-09 10:38 (6100 d 20:51 ago) @ Ohlbe Posting: # 4329 Views: 2,833 |
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Dear Ohlbe ❝ We also have some Ladies on the forum, don't discourage them from ❝ answering thank you  ❝ Which software ? Waters' is Masslynx, API 3000 runs with Analyst. the Analyst software ❝ This may happen due to rounding. [...] The software will use more digits ❝ than what you get on the printout. I agree with you, we are using 3 digits for manual calculations and the printout is with four digits ❝ In most software the user can define at least the number of decimals in ❝ the output. we will try and i will keep you posted ❝ Assessors will probably not recalculate. Some inspectors might. Some ❝ definitely will. But these ones are supposed to know about rounding. And ❝ that's something you can at least try and explain. would priniting a new set of results with 3 digits be accepted by the accessor, along with the rational behind having two sets of printouts with different results? Thank you and have a lovely day Edit: Full quote removed. Please delete anything from the text of the original poster which is not necessary in understanding your answer; see also this post! [Helmut] |
Ing. Helmut Schütz