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Re: Area reproducibility issues
Posted: Thu Mar 08, 2018 4:14 pm
by Reddy
Nothing it's just API.
Can I filter the sample n advise me which filter can choose for sample n diluent DCM
Re: Area reproducibility issues
Posted: Thu Mar 08, 2018 4:50 pm
by HPLC chemist
Reddy,
Probably Teflon syringe filters since they are inert (there are compatibility charts online). Use at least 0.22 um for an HPLC.
Re: Area reproducibility issues
Posted: Thu Mar 08, 2018 4:58 pm
by Reddy
K, but is it stable with acid n dcm.
Re: Area reproducibility issues
Posted: Thu Mar 08, 2018 6:07 pm
by GOM
by "n" do you mean in or and?
To avoid confusion, you may find it helpful to read the house rules regarding your use of unnecessary "phonetic" abbreviations
viewtopic.php?f=9&t=2679
Nothing it's just API.
Can I filter the sample n advise me which filter can choose for sample n diluent DCM
Why do you need to filter? You said that your sample has no other excipients.
Isn't your sample Divalproex sodium completely soluble in your solvent(s) after acidification ?
I apologise for my language difficulties in understanding your queries and replies
Re: Area reproducibility issues
Posted: Fri Mar 09, 2018 8:26 am
by Reddy
After acidification the sample turns to hazy for that - filtration is acceptable
Re: Area reproducibility issues
Posted: Fri Mar 09, 2018 7:02 pm
by GOM
a. have you tried centrifugation?
b. from where did you get your method?
c. is your sample a 500mg tablet and is it an enteric-coated capsule ?
If you can get full access to this article it is very interesting and relevant.
http://onlinelibrary.wiley.com/doi/10.1 ... NSE_DENIED
I cannot share a full copy with you, but interestingly, in the article is
"
Acknowledgement
We wish to express our sincere thanks to the management of Dr
Reddy’s Laboratories Ltd, Hyderabad for their support."
Is that you ? If not just a coincidence then you will already have a copy of it and a method to follow
Re: Area reproducibility issues
Posted: Mon Mar 12, 2018 2:53 am
by Reddy
[quote="GOM"]a. have you tried centrifugation?
b. from where did you get your method?
c. is your sample a 500mg tablet and is it an enteric-coated capsule ?
a) Centrifugation we dint tried, by considering DCM as a diluent.
b) method is from the vendor.
c) Its an API
DR. REDDY LABORATORY METHOD I'M ALREADY READ
Re: Area reproducibility issues
Posted: Thu Mar 15, 2018 2:10 pm
by James_Ball
One thing I know from running samples where acid is involved in the prep is that if you have excess acid in the injection it can damage the column and cause active sites in the inlet, which could reduce the response of the final standard.
You may need to take the DCM extract, filter it with 0.22um PTFE filter, then wash the extract with a base to neutralize the acid before injection. Since the active ingredient can complex with metals then possibly use a dilute ammonium hydroxide solution 1:1 V:V with the DCM and then remove the DCM layer and inject it.
If you examine the first few cm of the column and see dark spots then you definitely have a problem of the acid damaging the column.