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- Posts: 8
- Joined: Thu Mar 16, 2006 12:54 pm
Dear All,
Presentely I m working on Ethionamide & its Sulfoxide metabolite
(Ethionamide Sulfoxide) from plasma.The problem i ve faced is failure of
Sulfoxide linearity.Following procedure have used.
Stock Prep. in Methanol for Ethionamide & in CHCl3 for Ethionamide Sulfoxide bcauze Ethionamide Sulfoxide is not stable in Methanol.
CC dilutions for Ethionamide are prepared in MeOH : H2O (50:50).
CC dilutions for Ethionamide Sulfoxide are prepared in CHCl3.
Aqueous CC Preparation
50 µL of each of the above mixed with 800 µL of Mobile Phase
(ACN :0.1 % Acetic Acid 80:20 )+100 µL IS (Prothionamide).
Extraction Precedure:
200 µL of Spiked plasma + 40 µL of IS +40µL of 0.1 M Na Acetate
Vortex for 0.5 min
4 mL of Chloroform, Vortex , Centrifuge Separated 3 mL & Evaporated
& reconstituted in 750 µL of MP. 5 µL of same injected.
CC for ethionamide is fine (Both Aqueous & Extracted) but that of Sulfoxide is not linear.
The Difference in Ethionamide & Ethionamide Sulfoxide is one Oxygen atom.
I m using LCMSMS (API 2000) .
If any one worked on this please reply my email ID is
sandip.gurav@gmail.com
Presentely I m working on Ethionamide & its Sulfoxide metabolite
(Ethionamide Sulfoxide) from plasma.The problem i ve faced is failure of
Sulfoxide linearity.Following procedure have used.
Stock Prep. in Methanol for Ethionamide & in CHCl3 for Ethionamide Sulfoxide bcauze Ethionamide Sulfoxide is not stable in Methanol.
CC dilutions for Ethionamide are prepared in MeOH : H2O (50:50).
CC dilutions for Ethionamide Sulfoxide are prepared in CHCl3.
Aqueous CC Preparation
50 µL of each of the above mixed with 800 µL of Mobile Phase
(ACN :0.1 % Acetic Acid 80:20 )+100 µL IS (Prothionamide).
Extraction Precedure:
200 µL of Spiked plasma + 40 µL of IS +40µL of 0.1 M Na Acetate
Vortex for 0.5 min
4 mL of Chloroform, Vortex , Centrifuge Separated 3 mL & Evaporated
& reconstituted in 750 µL of MP. 5 µL of same injected.
CC for ethionamide is fine (Both Aqueous & Extracted) but that of Sulfoxide is not linear.
The Difference in Ethionamide & Ethionamide Sulfoxide is one Oxygen atom.
I m using LCMSMS (API 2000) .
If any one worked on this please reply my email ID is
sandip.gurav@gmail.com
Sandip Gurav, Mumbai
