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The following message was posted to: PharmPK
How gelling of serum occur during extraction with organic solvent?
Sim
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The following message was posted to: PharmPK
Hi
Gelling can occur due to the conditions you are using for extraction
like
pH, organic solvent etc.
You can avoid gelling by:
1. Check the pH conditions you are using for extraction.
2. Try a different solvent for extraction.
3. Try to centrifuge at higher speeds.
4. Freeze the sample in liquid nitrogen.
The best way would be is to optimize the solvent for extraction and pH
conditions.
Venkatesh Atul Bhattaram
Pharmacometrics
DPE-1, OCPB
CDER, FDA.
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Hi,
Most of the times you can get rid of the gelling by freezing the gels
you got at -80 and then allow them to melt for few minutes followed
by re-extraction.
best of luck
Ahmed Abdel-Fattah Othman.
Graduate student.
Pharmacokinetics and Biopharmaceutics lab
School of Pharmacy.
University of Maryland at Baltimore.
20 Penn Street.HSF-2
Baltimore, MD 21201
Phone:(410)706-7388
E-Mail:- aothm001.-at-.umaryland.edu
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The following message was posted to: PharmPK
When I extract from whole blood I intentionally let the blood in
organic go
to the gel stage in both my samples and standards and then spin down to
collect the supernatant for injection. Is that bad? Why? Is there
something different about following the same procedure for serum?
Thanks,
Rachel
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Rachel,
I wouldn't recommned letting blood gel while extraction because
gelling might hinder the extraction as it will not be mixed well with
the extracting solvent. If you are working with animal blood
samples, due to the less volume (around 0.5 ml) and the shape of
routine centrifuge tubes used for extraction will not allow a very
good mixing and you might see more variablity in the extraction
efficiency.
Thanks
Ayyappa
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Hi Rachel,
From my experience the problem arises if the gelation takes place
soon after starting the extraction and at a variable timing between
the samples. If this happens, the situation will be as if you were
extracting the samples for different time periods which may introduce
variability.
Ahmed Abdel-Fattah Othman.
Graduate student.
Pharmacokinetics and Biopharmaceutics lab
School of Pharmacy.
University of Maryland at Baltimore.
20 Penn Street.HSF-2
Baltimore, MD 21201
Phone:(410)706-7388
E-Mail:- aothm001.aaa.umaryland.edu
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Dear all
While extracting the analytes from matrices like serum, plasma etc,
if gelling/emulsion formation is happening we normally break the
emulsion by adding a pinch of common salt - NaCl and vortex the
sample. It nicely breaks the emulsion / gel and problem gets solved
without much hitch on that.
Thanking you and Regards
Vishwottam KANDIKERE
Principal Scientist - Biopharmaceutical Research
SUVEN LIFE SCIENCES Ltd
Serene Chambers, Road # 7,
Banjara Hills, Hyderabad 500 034
Phone : 9140 2355 6039, 3092 1169
Fax : 9140 2354 1152
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Hi,
You might also experience gelling if the ratio of volume of
extraction solvent to sample volume is too low. Apart from other
suggestions, you can try increasing the volume of extraction solvent
as well.
If gelling occurs you can break the gel by freezing it in liquid
nitrogen.
Hope this helps
Regards
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