Division Method of assay

Determine by liquid chromatography using the following conditions:

Sample solution: Weigh accurately about 100 mg of test sample into a 10-ml volumetric flask and add 8 ml of deionised water. Dissolve the sample completely using an ultra-sonification bath (10-15 min) and dilute to the mark with purified deionised water. Filter through a 0,45-micrometer filter.

Reference solution: Weigh accurately about 100 mg of α-cyclodextrin into a 10-ml volumetric flask and add 8 ml of deionised water. Dissolve the sample completely using an ultra-sonification bath and dilute to the mark with purified deionised water.

Chromatography: Liquid chromatograph equipped with a refractive index detector and an integrating recorder.

Column and packing: Nucleosil-100-NH2 (10 μm) (Macherey & Nagel Co. Düren, Germany) or similar.

Length: 250 mm

Diameter: 4 mm

Temperature: 40 °C

Mobile phase: acetonitrile/water (67/33, v/v)

Flow rate: 2,0 ml/min

Injection volume: 10 μl

Procedure: Inject the sample solution into the chromatograph, record the chromatogram, and measure the area of the α-CD peak. Calculate the percentage of α-cyclodextrin in the test sample as follows:

% α-cyclodextrin (dry basis) = 100 × (A_S/A_R) (W_R/W_S)

where

• A_s and A_R are the areas of the peaks due to α-cyclodextrin for the sample solution and reference solution, respectively.

• W_s and W_R are the weights (mg) of the test sample and reference α-cyclodextrin, respectively, after correcting for water content.