Specific rotation 781S:
between +137
and +145
.
Test solution
Transfer about 1 g of Mannitol, accurately weighed, to a 100-mL volumetric flask, and add 40 mL of ammonium molybdate solution (1 in 10), which previously had been filtered if necessary. Add 20 mL of 1 N sulfuric acid, dilute with water to volume, and mix.
Assay
Mobile phase
Use degassed water.
Resolution solution
Dissolve sorbitol and
USP Mannitol RS in water to obtain a solution having concentrations of about 4.8 mg per mL of each.
Standard preparation
Dissolve an accurately weighed quantity of
USP Mannitol RS in water, and dilute quantitatively with water to obtain a solution having a known concentration of about 4.8 mg per mL.
Assay preparation
Transfer about 0.24 g of Mannitol, accurately weighed, to a 50-mL volumetric flask, dissolve in 10 mL of water, dilute with water to volume, and mix.
Chromatographic system
(see
Chromatography 621)The liquid chromatograph is equipped with a refractive index detector that is maintained at a constant temperature and a 4-mm × 25-cm column that contains packing L19. The column temperature is maintained at a temperature between 30
and 85
controlled within ±2
of the selected temperature, and the flow rate is about 0.5 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the relative standard deviation for replicate injections is not more than 2.0%. In a similar manner, chromatograph the
Resolution solution: the resolution,
R, between the sorbitol and mannitol peaks is not less than 2.0.
Procedure
Separately inject equal volumes (about 20 µL) of the
Assay preparation and the
Standard preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
6H
14O
6, in the Mannitol taken by the formula:
50C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Mannitol RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.