Appearance: white or slightly coloured powder, slightly
hygroscopic.
Solubility: slightly soluble in water, soluble in methanol,
practically insoluble in heptane.
IDENTIFICATION
Carry out either tests A, B, C or A, B, E or B, C, D or B, D, E.
A. Specific optical rotation (2.2.7): ?137 to ?155.
Dissolve 0.250 g in methanol R and dilute to 25.0 mL with
the same solvent.
B. Infrared absorption spectrophotometry (2.2.24).
Comparison: esomeprazole magnesium trihydrate CRS.
C. Atomic absorption spectrometry (2.2.23) as described in the
test for magnesium.
The test solution shows the absorption maximum at
285.2 nm.
D. Enantiomeric purity (see Tests).
E. Ignite about 0.5 g ofthe substance to be examined according
to the procedure for the sulfated ash test (2.4.14). Dissolve
the residue in 10 mL of water R. 2 mL of this solution gives
the reaction of magnesium (2.3.1).
TESTS
Absorbance (2.2.25): maximum 0.20 at 440 nm.
Dissolve 0.500 g in methanol R and dilute to 25.0 mL with the
same solvent. Filter the solution through a membrane filter
(nominal pore size 0.45 μm).
Related substances. Liquid chromatography (2.2.29). Use the
normalisation procedure. Use freshly prepared solutions.
Test solution. Dissolve 3.5 mg of the substance to be examined
in the mobile phase and dilute to 25.0 mL with the mobile phase.
Reference solution (a). Dissolve 1 mg of omeprazole CRS and
1 mg of omeprazole impurity D CRS in the mobile phase and
dilute to 10.0 mL with the mobile phase.
Reference solution (b). Dissolve 3 mg of the om