Liquid Sorbitol (Non-crystallising)

Sorbitol Solution (70 per cent) (Non-crystallising)

(Ph Eur monograph 0437)

Excipient.

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Aqueous solution of a hydrogenated, partly hydrolysed starch.

• — anhydrous substance: 68.0 per cent m/m to 72.0 per cent m/m,

• — d-glucitol (d-sorbitol, C₆H₁₄O₆): 72.0 per cent to 92.0 per cent (anhydrous substance).

Clear, colourless, syrupy liquid, miscible with water.

A. Examine the chromatograms obtained in the assay.

Results  The principal peak in the chromatogram obtained with the test solution is similar in retention time to the principal peak in the chromatogram obtained with reference solution (a).

B. To 7.0 g add 40 mL of water R and 6.4 g of disodium tetraborate R. Allow to stand for 1 h, shaking occasionally, and dilute to 50.0 mL with water R. Filter if necessary. The angle of rotation (2.2.7) is + 1.5° to + 3.5°.

C. It is a clear, syrupy liquid at 25 °C.

The solution is clear (2.2.1) and colourless (2.2.2, Method II).

Dilute 7.0 g to 50 mL with water R.

Maximum 10 µS·cm^–1 measured on the undiluted liquid sorbitol (non crystallising) while gently stirring with a magnetic stirrer.

Maximum 0.2 per cent calculated as glucose equivalent.

To 5.0 g add 6 mL of water R, 20 mL of cupri-citric solution R and a few glass beads. Heat so that boiling begins after 4 min and maintain boiling for 3 min. Cool rapidly and add 100 mL of a 2.4 per cent V/V solution of glacial acetic acid R and 20.0 mL of 0.025 M iodine. With continuous shaking, add 25 mL of a mixture of 6 volumes of hydrochloric acid R and 94 volumes of water R and, when the precipitate has dissolved, titrate the excess of iodine with 0.05 M sodium thiosulfate using 1 mL of starch solution R, added towards the end of the titration, as indicator. Not less than 12.8 mL of 0.05 M sodium thiosulfate is required.

Maximum 9.3 per cent calculated as glucose equivalent.

To 6.0 g add 35 mL of water R, 40 mL of 1 M hydrochloric acid and a few glass beads. Boil under a reflux condenser for 4 h. Cool and neutralise with dilute sodium hydroxide solution R using 0.2 mL of bromothymol blue solution R1 as indicator. Cool and dilute to 100.0 mL with water R. To 3.0 mL of the solution add 5 mL of water R, 20 mL of cupri-citric solution R and a few glass beads. Heat so that boiling begins after 4 min and maintain boiling for 3 min. Cool rapidly and add 100 mL of a 2.4 per cent V/V solution of glacial acetic acid R and 20.0 mL of 0.025 M iodine. With continuous shaking, add 25 mL of a mixture of 6 volumes of hydrochloric acid R and 94 volumes of water R. When the precipitate has dissolved, titrate the excess of iodine with 0.05 M sodium thiosulfate using 1 mL of starch solution R, added towards the end of the titration, as indicator. Not less than 8.0 mL of 0.05 M sodium thiosulfate is required.

Maximum 0.5 ppm.

Maximum 1 ppm.

28.0 per cent to 32.0 per cent m/m, determined on 0.1 g.

Liquid chromatography (2.2.29).

Test solution  Mix 1.00 g of the substance to be examined with 20 mL of water R and dilute to 50.0 mL with the same solvent.

Reference solution (a)  Dissolve 55.0 mg of sorbitol CRS in 2 mL of water R and dilute to 5.0 mL with the same solvent.

Reference solution (b)  Dissolve 55 mg of mannitol R and 55 mg of sorbitol R in 2 mL of water R and dilute to 5.0 mL with the same solvent.

• — size: l = 0.3 m, Ø = 7.8 mm,

• — stationary phase: strong cation exchange resin (calcium form) R (9 µm),

• — temperature: 85 ± 1 °C.

Mobile phase  degassed water R.

Flow rate  0.5 mL/min.

Detection  Refractometer maintained at a constant temperature.

Injection  20 µL.

Run time  3 times the retention time of sorbitol.

Relative retention  With reference to sorbitol (retention time = about 27 min): mannitol = about 0.8.

System suitability  Reference solution (b):

• — resolution: minimum 2 between the peaks due to mannitol and to sorbitol.

Calculate the percentage content of d-sorbitol from the areas of the peaks and the declared content of sorbitol CRS.

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