Solution A Mix 11 volumes of
0.25M trisodium orthophosphate and 22 volumes of 0.5M anhydrous disodium
hydrogen orthophosphate, dilute to 100 volumes with water and adjust the pH, if
necessary, to 11.0 with orthophosphoric acid or 10M sodium hydroxide, as
appropriate.
Solution B : Mix 1 volume of
10M sodium hydroxide with 99 volumes of 0.05M phosphate buffer
solution pH 4.5
Solution C : Mix 5.2 volumes of
1M anhydrous sodium dihydrogen orthophosphate and 63.2 volumes of 0.5M
anhydrous disodium hydrogen orthophosphate, dilute to 1000 volumes with
water and adjust the pH, if necessary, to 7.6 with orthophosphoric acid
or 10M sodium hydroxide, as appropriate
TEST CONDITIONS
(a) Use
Apparatus 2, rotating the paddle at 100 revolutions per minute.
(b) Use as the
media the solutions described sequentially below.
First stage (pH 4.5)
Use as the
medium 700 mL of 0.05M phosphate buffer solution pH 4.5. After 45 minutes,
withdraw 5 mL of the medium, filter the aliquot, dilute to 25 mL with solution
A and retain the samples for analysis as described below. Proceed immediately
to the final stage.
Final stage (pH 6.8)
Within 5
minutes, add 200 mL of solution B at 37° to the vessel. Maintain the rotation
speed at 100 revolutions per minute and continue to operate the apparatus for
45 minutes. Withdraw 5 mL of the medium, filter the aliquot, dilute to 25 mL
with solution A and retain the samples for analysis as described below.
Carry out the method
for liquid chromatography, using the following solutions.
(1) Test solution :
Use the sample solutions taken above.
(2) Standard solution
: Dissolve a sufficient quantity of omeprazole ws in solution A and dilute
with water;
the concentration of the final solution should be the same as that expected for
solution (1).
( Standard
solution : Weigh accurately about 10 mg of Omeprazole ws &
tranafer it into 100 ml volumetric flask & dissolve it into solution A and
dilute with water. Further dilute 5 ml to 100 ml with solution A)
CHROMATOGRAPHIC
CONDITIONS
(a) Use a
stainless steel column (15 cm × 2 mm) packed with octadecylsilyl silica gel
for chromatography R (5µm) (Nucleosil C18 is suitable). Use a suitable guard
column.
(b) Use
isocratic elution and the mobile phase described below.
(c) Use a flow
rate of 0.25 mL per minute.
(d) Use a
column temperature of 30°.
(e) Use a
detection wavelength of 302 nm.
(f) Inject 10
µL of each solution.
(g) Allow the
chromatography to proceed for 8 times the retention time of omeprazole.
MOBILE PHASE
25 volumes of
solution C, 35 volumes of water and 40 volumes of acetonitrile. Adjust the pH,
if necessary, to 7.6 with orthophosphoric acid or 10M sodium hydroxide, as
appropriate.
SYSTEM SUITABILITY
The symmetry
factor of the peak due to omeprazole is not more than 2.0.
DETERMINATION OF
CONTENT
Calculate the total
content of C17H19N3O3S in the
medium using the declared content of C17H19N3O3S
in omeprazole ws.
Calculation :
First stage ( pH 4.5
)
Spl
Area Wt.of Std (mg) 5 700 25 Std
potency (as is)
%
=----------------x-----------------------x---------x---------x---------x-------------------------------x 100
Std
Area 100 100 20 5
100
Calculation :
Final stage ( pH 6.8 )
Spl
Area Wt.of Std (mg) 5
900 25
Std potency (as is)
% =----------------x-----------------------x---------x---------x---------x----------------------------x 100
Std
Area 100 100 20 5 100
LIMITS
The amount of
omeprazole released after the first stage is not more than 10% of the stated
amount.
The amount of omeprazole released after the
final stage is not less than 65% (Q) of the stated amount.
