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- Posts: 8
- Joined: Mon Aug 11, 2014 7:13 am
I'm trying to repeat the latest version of European Pharmacopoeia analytical method (:1317), Ethanol (96%) / Volatile impurities (GC).
Link to previous version:
http://www.drugfuture.com/Pharmacopoeia ... /1317E.PDF
In newest method version only acetaldehyde + acetal calculation formula was changed:
[(10 x Ae)/(At - Ae)] + [(30 x Ce)/(Ct - Ce)] x (44.05/118.2)
For analysis I'm using DB-624 30m x 0.32 mm x 1.8 µm
As result I'm getting following areas of the peaks:
- 4-methylpentan-2-ol (Test s. B) - 157
- Methanol (Ref. s. A) - 35
- Acetaldehyde (Ref. s. B) - 2.6
- Methanol (Ref. s. B) - 1.8
- Acetal (Ref. s. C) - 9.1
- Benzene (Ref. s. D) - 1.2
In method is written that I supposed to used disregard limit that is "0.03 times the area of the peak corresponding to 4-methylpentan-2-ol (Test s. B)". So if I understood correctly disregard limit supposed to be 4.7.
So the first question is, do I need to apply calculated disregard limit to both Test solutions (A and B), or it's only for Test s. B?
The second question related to Acetaldehyde + Acetal calculation formula. In case in Test s. A Acetaldehyde or Acetal peak area is bigger then correcponding peak area it Ref. s., then calculation result will be negative.
How such cases supposed to be handle?
I checked all topics on the forum that related to this method, but unfortunately I can't find answers.
Thank you in advance,
Dmitrij