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The following message was posted to: PharmPK
Dear All,
I am doing bioanalytical methods and estimation on UPLC with PDA
detector, and plasma sample preparation using ACN precipitaion method.
Now i have one drug which is insoluble in ACN and methanol and i
cannot go beyond precipitation method, so i did tried using 10% DMSO in
ACN and recovery was above 85%, which i think quite good. But at lower
concentration some plasma interference was observed which is not
desired to proceed further. I tried the blank plasma with 100 % ACN
where the interference was not in same RT which i have seen in 10%
DMSO in ACN. Which reveals it might be due to DMSO. Can anybody help
me to solve the same. using 10% DMSO or any thing else to reduce the
plasma interferences. Its really challenging to solve and please don't
suggest to have Liq-Liq extraction.
Experts opinions are really appreciated.
Thanks in advance,
Best regards,
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If the drug is not acid labile then you may want to consider using perchloric acid (~6% in water). Add the acid while vortexing the tube. There are instances when this approach provides the same recovery as acetonitile and the extract is "cleaner".
Hope this helps,
Angus
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Try solid Phase extraction Aslam.
regards
Yati YChugh.at.wockhardtin.com
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Dear Aslam,
You can try with 4% TCA(Trichloroacetic acid) in water like ACN if your compd is not acid labile to precipitate the protein. Sometimes it may give you clean extraction.
Best regards rammohan.bera.aaa.tcgls.com
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If you want to stick to protein precipitation, i would try few things such as:
1- acidic ACN (5-10% formic acid in ACN) or alkaline ACN (using 5-10% NH4OH in ACN) both evaporate pretty fast, but you have to check stability.
2-Other organic solvents such as EtOH, longer chain alcohol mixed with ACN or MeOh (to make it easier to evaporate if you are doing a blow-down)
3-Acid precipitation using formic acid or alakline precipitation using NH4-OH, both evaporates pretty fast.
yazen alnouti
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You can try adding 50 uL of Trichloroacetic acid (2mM) to the plasma and later add 300 uL of acetonitrile/methanol for 100 uL of plasma and check the recovery. May be as DMSO is universal solvent, it has the tendency to solubilise/extract compounds varying widely in their polarity. Instead of using 10% DMSO, where you are getting 85% recovery, you can think about reducing the DMSO pecentage used. May be the percentage of DMSO used is more as far as I am concerned. also try using acid, DMSO and acetonitrile and check the recovery.
With regards,
Vijay,
G7 Synergon Pvt Ltd.
veeravalli vijay bhaskar
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